Titanium has an HCP unit cell for which the ratio of the lattice parameters cais 1.58. If the radius of the Be atom is 0.1445 nm, (a) determine the unit cell volume, and (b) calculate the theoretical density of Ti, given that its atomic weight is 47.87 g/mol

Answers

Answer 1

Answer :

(a) The volume of unit cell is, [tex]9.91\times 10^{-23}cm^3/\text{ unit cell}[/tex]

(b) The theoretical density of Ti is, [tex]4.81g/cm^3[/tex]

Explanation :

(a) First we have to calculate the volume of the unit cell.

Formula used :

[tex]V=6r^2c\sqrt {3}[/tex]

where,

V = volume of unit cell  = ?

r = atomic radius = [tex]0.1445nm=1.445\times 10^{-8}cm[/tex]

conversion used : [tex](1nm=10^{-7}cm)[/tex]

Ratio of lattice parameter = c : a = 1.58 : 1

So, c = 1.58 a

And,  a = 2r

c = 1.58 × 2r

Now put all the given values in this formula, we get:

[tex]V=6\times r^2\times (1.58\times 2r)\sqrt {3}[/tex]

[tex]V=6\times r^3\times (1.58\times 2)\sqrt {3}[/tex]

[tex]V=6\times (1.445\times 10^{-8}cm)^3\times (1.58\times 2)\sqrt {3}[/tex]

[tex]V=9.91\times 10^{-23}cm^3/\text{ unit cell}[/tex]

The volume of unit cell is, [tex]9.91\times 10^{-23}cm^3/\text{ unit cell}[/tex]

(b) Now we have to calculate the density of Ti.

Formula used for density :

[tex]\rho=\frac{Z\times M}{N_{A}\times a^{3}}[/tex]

[tex]\rho=\frac{Z\times M}{N_{A}\times V}[/tex]     ..........(1)

where,

[tex]\rho[/tex] = density  of Ti = ?

Z = number of atom in unit cell  = 6 atoms/unit cell (for HCP)

M = atomic mass  = 47.87 g/mol

[tex](N_{A})[/tex] = Avogadro's number  = [tex]6.022\times 10^{23}atoms/mole[/tex]

[tex]a^3=V[/tex] = volume of unit cell  = [tex]9.91\times 10^{-23}cm^3/\text{ unit cell}[/tex]

Now put all the values in above formula (1), we get:

[tex]\rho=\frac{6\times 47.87}{(6.022\times 10^{23})\times (9.91\times 10^{-23})}[/tex]

[tex]\rho=4.81g/cm^3[/tex]

The theoretical density of Ti is, [tex]4.81g/cm^3[/tex]


Related Questions

In a
constant volume bomb calorimeter, the combustion of 0.6654 gof an
organic compound with a molecular mass of 46.07 amu causesthe
temperature in the calorimeter to rise from 25.000oC to
30.589 oC. The total heat capacity ofthe calorimeter
and all its contents is 3576 JoC-1.
What is the energy of combustion ofthe organic
compound, DU/ kJ
mol-1?
Pay attention to sign and significant figures!
If you wish to use scientific notation, use the "e" format:
e.g.7.31e4 = 73100 or 1.90e-2 = 0.0190. Do not
enterunits.

Answers

Answer:

1384 kJ/mol

Explanation:

The heat absorbed by the calorimeter is equal to the heat released due to the combustion of the organic compound. C is the total heat capacity of the calorimeter and Δt is the change in temperature from intial to final:

Q = CΔt = (3576 J°C⁻¹)(30.589°C - 25.000°C) = 19986.264 J

Extra significant figures are kept to avoid round-off errors.

We then calculate the moles of the organic compound:

(0.6654 g)(mol/46.07) = 0.0144432 mol

We then calculate the heat released per mole and convert to the proper units. (The conversion between kJ and J is infinitely precise and is not involved in the consideration of significant figures)

(19986.264 J)(1kJ/1000J) / (0.0144432 mol) = 1384 kJ/mol

Enter your answer in the provided box. Remember to enter your answer to the correct number of significant figures. For the reaction: A(g) + B(g) → AB(g) the rate is 0.23 mol/L·s, when [A]0 = [B]0 = 1.0 mol/L. If the reaction is first order in B and second order in A, what is the rate when [A]0 = 2.0 mol/L and [B]0 = 4.6 mol/L?

Answers

Answer : The rate law is 4.232 mol/L.s

Explanation :

First we have to calculate the value of rate constant.

According to the question, the expression for rate law will be:

[tex]Rate=k[A]^2[B][/tex]

where,

k = rate constant

As we are given :

Rate law = 0.23 mol/L.s

Initial concentration of A = 1.0 mol/L

Initial concentration of B = 1.0 mol/L

Now put all the given values in the above rate law expression, we get:

[tex]0.23mol/L.s=k\times (1.0mol/L)^2\times (1.0mol/L)[/tex]

[tex]k=0.23M^{-2}s^{-1}[/tex]

Now we have to calculate the rate law when initial concentration of A and B is 2.0 mol/L and 4.6 mol//L respectively.

The expression for rate law will be:

[tex]Rate=k[A]^2[B][/tex]

where,

k = rate constant = [tex]0.23M^{-2}s^{-1}[/tex]

Rate law = ?

Initial concentration of A = 2.0 mol/L

Initial concentration of B = 4.6 mol/L

Now put all the given values in the above rate law expression, we get:

[tex]Rate=(0.23M^{-2}s^{-1})\times (2.0mol/L)^2\times (4.6mol/L)[/tex]

[tex]Rate=4.232mol/L.s[/tex]

Therefore, the rate law is 4.232 mol/L.s

The study of chemicals and bonds is called chemistry. When the amount of reactant and product are equal then is said to be an equilibrium state.

The correct answer is 4.232.

What is equilibrium constant?The equilibrium constant of a chemical reaction is the value of its reaction quotient at chemical equilibrium.A state approached by a dynamic chemical system after sufficient time has elapsed at which its composition has no measurable tendency towards further change.

According to the question, the expression for rate law will be:

[tex]Rate =k[A]^2[B][/tex]

where,

k = rate constant

The data is given as follows:-

Rate law = 0.23 mol/L.sInitial concentration of A = 1.0 mol/LInitial concentration of B = 1.0 mol/L

Place all the values in the equation and solve it

[tex]0.23= k*1^2*1\\\\k= 0.23[/tex]

Now we have to calculate the rate law when the initial concentration of A and B is 2.0 mol/L and 4.6 mol//L respectively.

The expression for rate law will be:

[tex]Rate =k[A]^2[B][/tex]

where,

k = rate constant = 0.23Initial concentration of A = 2.0 mol/LInitial concentration of B = 4.6 mol/L

[tex]Rate = 0.23*2^2*4.6[/tex]

Hence, the rate will be 4.232.

For more information about the rate of the equation, refer to the link:-

https://brainly.com/question/16759172

What is the least amount of energy that can be emitted by an excited electron in a hydrogen atom falling from an excited state directly to the n = 3 state? What is the quantum number n for the excited state? Humans cannot visually observe the photons emitted in this process. Why not?

Answers

Answer:

The least amount of energy emitted in this case is 0.6 eV.

The corresponding quantum number n would be n=4.

The wavelenght asociated to the emitted photon would be 2.06 [tex]\mu[/tex]m, corresponding to the Infrared spectrum.

Explanation:

For calculating the energy of an electron emitted/absorbed in an electronic transition of the hydrogen atom, the next equation from the Bohr model can be used:

[tex]E=E_{0} Z^2 [\frac{1}{n_1^2}-\frac{1}{n_2^2}][/tex]

, where E is the photon energy, [tex]E_0[/tex] is the energy of the first energy level (-13.6 eV), Z is the atomic number, [tex]n_1[/tex] is the quantum number n of the starting level and [tex]n_2[/tex] the quantum number n of the finishing level. In this case, [tex]n_2=3[/tex], and [tex]n_1=4[/tex], because this excited level is the next in energy to n=3.

Considering that [tex]1 eV= 1.60217662x10^{-19} J[/tex], and using the Planck equation [tex]E=h\nu=\frac{hc}{\lambda}[/tex], you can calculate the wavelenght or the frequency associated to that photon. Values in the order of [tex]\mu[/tex]m in wavelenght belong to the Infrared spectrum, wich can not being seen by humans.

Answer:

1. [tex]E=1.059x10^{-19}J[/tex]

2. [tex]n=4[/tex]

3. The associated wavelength belongs to the infrared spectrum which is invisible for humans.

Explanation:

Hello,

1. At first, according to the equation:

[tex]E=E_oZ^2(\frac{1}{n_1^2}-\frac{1}{n_2^2})[/tex]

Whereas [tex]E[/tex] is the emitted energy, [tex]E_o[/tex] the first level energy, [tex]Z[/tex] the atomic number, [tex]n_1[/tex] the first level and [tex]n_2[/tex] the second level. In such a way, the closest the [tex]n[/tex]'s are, the least the amount of emitted energy, therefore, [tex]n_1=3[/tex] (based on the statement) and [tex]n_2=4[/tex], thus, the least amount of energy turns out being:

[tex]E=(2.179x10^{-18}J)(1^2)(\frac{1}{3^2}-\frac{1}{4^2})\\E=1.059x10^{-19}J[/tex]

2. Secondly, and based on the first question, the quantum number for the excited state is mandatorily [tex]n=4[/tex]

3. Finally, to substantiate why we cannot observe the emitted photons we apply the following equation:

[tex]E=\frac{hc}{\lambda} \\\lambda=\frac{hc}{E}=\frac{(6.62607004x10^{-34} m^2 kg / s)(299 792 458m/s)}{1.059x10^{-19}m^2 kg / s^2}  \\\lambda=1.88x10^{-6}m[/tex]

Whereas the obtained wavelength corresponds to the infrared spectrum which is not observable by humans.

Best regards.

Calculate the vapor pressure (in torr) at 298 K in a solution prepared by dissolving 42.4 g of the non-volatile non-electrolye urea {CO(NH2)2} in 195 g of ethanol. The vapor pressure of ethanol at 298 K is 58.9 torr. Give your answer to 2 decimal places.

Answers

Answer:

The vapor pressure at 298 K for this solution is 50,49 Torr.

Explanation:

We have to apply Raoult's law to solve this which its formula is:

P pure sv° - P sl = P pure sv° . X (molar fraction)

ΔP = P pure sv° . X (molar fraction)

58,9 Torr - P sl = 58,9 Torr . X

Molar mass urea CO(NH2)2: 60,06 g/m

Molar mass ethanol: 46,07 g/m

Moles for urea: 42,4 g /  60,06 g/m = 0,705 moles

Moles for ethanol: 195 g / 46,06 g/m = 4,233 moles

X (molar fraction): moles from solute / moles from solute + moles from solvent

X (molar fraction): 0,705 / 0,705 + 4,233 = 0,142

58,9 Torr - P sl = 58.9 Torr . 0,142

58,9 Torr - 8,40 Torr = P sl

50,49 Torr = P sl

Calculation: If you have a pH of 5.5 for a weak acid with a pKa of 4.76, then is there more A- or more HA in the solution? Explain why in words using your knowledge of positive or negative log numbers.

Answers

Answer:

lets set the ratio -A/HA as R:

pH = pKa + log(R,10) => pKa + log10(R)

pH = 5.5

pKa = 4.76

R => 10^(pH - 4.76)

10^(pH - 4.76) => 5.4954

Given R (-A/HA) a number bigger than 1, then the concentration of  -A is bigger than HA

Explanation:

Answer:

There is more A⁻ than HA in the solution  

Explanation:

The equation for the ionization of a weak acid is

HA + H₂O ⇌H₃O⁺ + OH⁻

When HA and A⁻ are present in comparable amounts, we can use the Henderson-Hasselbalch equation:

[tex]\begin{array}{rcl}\text{pH} &=& \text{pK}_{\text{a}} + \log\dfrac{[\text{A}^{-}]}{\text{[HA]}}\\\\5.5 & = & 4.76 + \log\dfrac{[\text{A}^{-}]}{\text{[HA]}}\\\\0.74 & = & \log\dfrac{[\text{A}^{-}]}{\text{[HA]}}\\\end{array}[/tex]

0.74 is a positive number, and a number must be greater than one for its logarithm to be positive. That is,

[tex]\begin{array}{rcl}\dfrac{[\text{A}^{-}]}{\text{[HA]}} & > & 1\\\\\textbf{[A]}^{-} & > & \textbf{[HA]}\\\end{array}[/tex]

A solution of HNO3 is standardized by reaction with pure sodium carbonate. 2H++Na2CO3⟶2Na++H2O+CO2 A volume of 23.45±0.05 mL of HNO3 solution was required for complete reaction with 0.9616±0.0009 g of Na2CO3 , (FM 105.988±0.001 g/mol ). Find the molarity of the HNO3 solution and its absolute uncertainty. Note: Significant figures are graded for this problem. To avoid rounding errors, do not round your answers until the very end of your calculations.

Answers

Final answer:

By calculating the moles of Na2CO3, we can infer the moles of HNO3 due to their 1:1 ratio in the reaction. Dividing the moles of HNO3 with the volume of the solution in liters gives the molarity, which is 0.39 M. The absolute uncertainty is calculated using a specific formula and found to be 0.001 M.

Explanation:

The molarity, M, of a solution is the amount of solute divided by the volume of solution (in Liters). We'll start by calculating the moles of Na2CO3, which is obtained by dividing the given mass of the Na2CO3 by its molar mass.

Calculate moles of Na2CO3 = mass (g) / molar mass (g/mol) = 0.9616 g / 105.988 g/mol = 0.00907 mol.

Since the reaction between HNO3 and Na2CO3 is a 1:1 ratio, the moles of HNO3 is equal to the moles of Na2CO3. Now we know amount of solute (HNO3) is 0.00907 mol. To express the volume of the HNO3 solution in liters, we divide by 23.45 mL by 1000 mL/L, giving 0.02345 L.

Molarity of HNO3 = moles of solute / volume of solution in L = 0.00907 mol / 0.02345 L = 0.387 mol/L or M.

The absolute uncertainty can be found using the following formula: (Delta M/M) = sqrt((Delta m / m)^2 + (Delta V / V) ^2) = sqrt((0.0009 / 0.9616)^2 + (0.05 / 23.45)^2) = 0.002. Therefore, absolute uncertainty = M * (Delta M/M) = 0.387 M * 0.002 = 0.000774 M.

The final answer with significant figures: The molarity of HNO3 = 0.39 ± 0.001 M.

Learn more about Molarity and Uncertainty here:

https://brainly.com/question/34662977

#SPJ12

Using the bond energies below, calculate an estimate of AHrxn for the gas phase reaction: QX3 + 3H20 => Q(OH)3 + 3HX Do not enter units with your answer. Bond BE (kJ/mol) Q-X 240 O-H 464 Q-O 359 H-X 449

Answers

Final answer:

To calculate the approximate enthalpy change for the given reaction, we need to consider the bond energies of the bonds in the reactants and products. The approximate enthalpy change is -3818 kJ.

Explanation:

To calculate the approximate enthalpy change (ΔH) for the given reaction, we need to consider the bond energies of the bonds in the reactants and products. The reaction is:

QX3 + 3H20 => Q(OH)3 + 3HX

We can calculate the energy absorbed or released by breaking and forming these bonds.

First, we calculate the energy required to break the bonds in the reactants:

For Q-X bonds: 3 mol x 240 kJ/mol = -720 kJFor O-H bonds: 3 mol x 464 kJ/mol = -1392 kJ

Then, we calculate the energy released when the bonds in the products are formed:

For Q-O bonds: 1 mol x 359 kJ/mol = -359 kJFor H-X bonds: 3 mol x 449 kJ/mol = -1347 kJ

Finally, we sum up the energy changes:

-720 kJ + (-1392 kJ) + (-359 kJ) + (-1347 kJ) = -3818 kJ

Therefore, the approximate enthalpy change for the reaction is -3818 kJ.

Sodium dodecanoate is soluble in water even though it contains a large hydrophobic segment. How does this molecule interact with its surroundings to facilitate solubility?

Answers

Answer:

Sodium laurate, also known as sodium dodecanoate, is a soap. It is the salt of lauric acid. It is an amphiphilic organic molecule which is composed of a hydrophilic head (polar ) and a hydrophobic tail (non-polar fatty acid).

In a aqueous solution, it leads to the formation of a micelle. The hydrophilic head of the molecule interacts with the surrounding polar solvent molecules. Thereby, making the micelle soluble in the solution. Whereas, the hydrophobic tails present in the core of micelle, interacts with the non-polar oil particles.

My professor gave me two questions to solve using the Van Der Waals Equation. She told us to solve for P and the second one we have to solve for b

She wants an explanation how we got our answers. What confusing is the fact that she wants the answers in units but she never gave us any numbers to plot for the equations unless she wants us to use Si units. She did however say P=atmosphere, b=litters, and T=kelvin


Van der waals equation

(P+n^2a/V^2)(V-nb)=nRT. solve for P

T=kelvin
P=atmosphere
b=litters

profesor wants units, so im guessing she wants us to use Si units

Answers

Answer:

P=atm

[tex]b=\frac{L}{mol}[/tex]

Explanation:

The problem give you the Van Der Waals equation:

[tex](P+\frac{n^{2}a}{V^{2}})(V-nb)=nRT[/tex]

First we are going to solve for P:

[tex](P+\frac{n^{2}a}{V^{2}})=\frac{nRT}{(V-nb)}[/tex]

[tex]P=\frac{nRT}{(V-nb)}-\frac{n^{2}a}{v^{2}}[/tex]

Then you should know all the units of each term of the equation, that is:

[tex]P=atm[/tex]

[tex]n=mol[/tex]

[tex]R=\frac{L.atm}{mol.K}[/tex]

[tex]a=atm\frac{L^{2}}{mol^{2}}[/tex]

[tex]b=\frac{L}{mol}[/tex]

[tex]T=K[/tex]

[tex]V=L[/tex]

where atm=atmosphere, L=litters, K=kelvin

Now, you should replace the units in the equation for each value:

[tex]P=\frac{(mol)(\frac{L.atm}{mol.K})(K)}{L-(mol)(\frac{L}{mol})}-\frac{(mol^{2})(\frac{atm.L^{2}}{mol^{2}})}{L^{2}}[/tex]

Then you should multiply and eliminate the same units which they are dividing each other (Please see the photo below), so you have:

[tex]P=\frac{L.atm}{L-L}-atm[/tex]

Then operate the fraction subtraction:

P=[tex]P=\frac{L.atm-L.atm}{L}[/tex]

[tex]P=\frac{L.atm}{L}[/tex]

And finally you can find the answer:

P=atm

Now solving for b:

[tex](P+\frac{n^{2}a}{V^{2}})(V-nb)=nRT[/tex]

[tex](V-nb)=\frac{nRT}{(P+\frac{n^{2}a}{V^{2}})}[/tex]

[tex]nb=V-\frac{nRT}{(P+\frac{n^{2}a}{V^{2}})}[/tex]

[tex]b=\frac{V-\frac{nRT}{(P+\frac{n^{2}a}{V^{2}})}}{n}[/tex]

Replacing units:

[tex]b=\frac{L-\frac{(mol).(\frac{L.atm}{mol.K}).K}{(atm+\frac{mol^{2}.\frac{atm.L^{2}}{mol^{2}}}{L^{2}})}}{mol}[/tex]

Multiplying and dividing units,(please see the second photo below), we have:

[tex]b=\frac{L-\frac{L.atm}{atm}}{mol}[/tex]

[tex]b=\frac{L-L}{mol}[/tex]

[tex]b=\frac{L}{mol}[/tex]

Write 0.00000009345 in Engineering Notation with 3 significant figures

Answers

Answer:

[tex]93.43\times 10^{-9}[/tex]

Explanation:

Scientific notation is the way of writing numbers which are either large or small. The number is written in the scientific notation when the number is between 1 and 10 and then multiplied by the power of 10. Engineering notation is the same version of the scientific notation but the number can be between 1 and 1000 and in this exponent of the ten is divisible by three.

For example, [tex]1000^2[/tex] is to be written as [tex]10^6[/tex] in engineering notation.

The given number:

0.00000009345 can be written as [tex]93.425\times 10^{-9}[/tex]

Answer upto 4 significant digits = [tex]93.43\times 10^{-9}[/tex]

Must show units and how they cancelli 1.) 175 km to um 3.) 385 nm to dm 5.) 492 um tom 7.) 52 x 103 dm to mm 9.) 321x 1035 mm to km 11.) 456 x 103 m to km 13.) 422 x 103 m to nm 15.) 4.87 x 1030m to pm 17.) 5.26 x 103 m to um 19.) 1.25 x 1035 m to Mm 21.) 4.22 x 103 Tm to nm

Answers

Explanation:

1.) 175 km to μm

[tex]1 km=10^9 \mu m[/tex]

[tex]175 km=175\times 10^9\mu m=1.75\times 10^{11} \mu m[/tex]

3.) 385 nm to dm

[tex]1 nm=10^{-8} dm[/tex]

[tex]385 nm=385\times 10^{-8} dm=3.85\times 10^{-6} dm[/tex]

5.) 492 μm  to m

1 μm =  [tex]10^{-6} m[/tex]

[tex]492 \μm=492\times 10^{-6} m=4.92\times 10^{-4} m[/tex]

7.) [tex]52\times 10^3[/tex] dm to mm

1 dm = 100 mm

[tex]52\times 10^3 dm=52\times 10^3\times 100 mm=5.2\times 10^{6}dm[/tex]

9.) [tex]321\times 10^{35}[/tex] mm to km

[tex]1 mm = 10^{-6} km[/tex]

[tex]321\times 10^{35} mm=321\times 10^{35}\times 10^{-6} km=3.21\times 10^{31} km[/tex]

11.) [tex]456\times 10^3[/tex] m to km

m = 0.001 km

[tex]456\times 10^3m =456\times 10^3 m\times 0.001 km=456 km[/tex]

13.) [tex]422\times 10^3[/tex] m to nm

[tex]1 m = 10^{9} nm[/tex]

[tex]422\times 10^3 m=422\times 10^3\times 10^{9} nm=4.22\times 10^{14} nm[/tex]

15.) [tex]4.87\times 10^{30}[/tex] m to pm

[tex]1 m = 10^{12} pm[/tex]

[tex]4.87\times 10^{30} m=4.87\times 10^{30}\times 10^{12} pm=4.82\times 10^{42} pm[/tex]

17.) [tex]5.26\times 10^3[/tex] m to um

1 m =  [tex]10^{6} \mu m[/tex]

[tex]5.26\times 10^3 m=5.26\times 10^3\times 10^6 \mu m=5.26\times 10^{9} \mu m[/tex]

19.) [tex]1.25\times 10^{35}[/tex]m to Mm

1 m =  [tex]10^{-6} Mm[/tex]

[tex]1.25\times 10^{35} m=1.25\times 10^{35}\times 10^{-6} Mm=1.25\times 10^{-29} Mm[/tex]

21.) [tex]4.22\times 10^3[/tex] Tm to nm

[tex]1 Tm = 10^{21} nm[/tex]

[tex]4.22\times 10^3 Tm=4.22\times 10^3\times 10^{21} nm=4.22\times 10^{24} nm[/tex]

An adult eats food whose nutritional energy totals
approximately2.2*103 Cal per day. The adult
burns2.0*103 Cal per day. How much excess
nutritionalenergy, in kilojoules, does the adult consume per day?
If 1lb of fat is stored by the body for each
14.6*103kilojoules of excess nutritional energy
consumed, how long will ittake this person to gain 1 lb.

Answers

Answer:

0.8368 kiloJoules of an excess nutritional energy is consumed by an adult in a day.

It will take 17,447.41 days long to gain 1 lb of fat by this person.

Explanation:

Calorie intake of an adult in a day =[tex]2.2\times 10^3 calorie[/tex]

Calorie burnt by an adult in a day = [tex]2.0\times 10^3 calorie[/tex]

Excess  nutritional energy in day=

[tex](2.2\times 10^3 calorie)-(2.0\times 10^3 calorie)[/tex]

[tex]=2.0\times 10^2 calorie[/tex]

1 kcal = 4.184 kJ

So , 1000 cal = 4.184 kJ

[tex]1 cal = 4.184\times 10^{-3} kJ[/tex]

[tex]2.0\times 10^2 calorie=2.0\times 10^2\times 4.184\times 10^{-3} kJ[/tex]

[tex]=0.8368 kJ[/tex]

0.8368 kiloJoules of an excess nutritional energy is consumed by an adult in a day.

[tex]14.6\times 10^3[/tex] kilo joules of excess nutritional energy = 1 lb fat

The 1 kilo joule of excess nutritional energy  = [tex]\frac{1}{14.6\times 10^3}[/tex] lb fat

Excessive nutritional energy of an adult per day = 0.8368 kiloJoules

Amount of fat gained by an adult per day =

= [tex]0.8368 kiloJoules\times \frac{1}{14.6\times 10^3}=5.7315\times 10^{-5} lb[/tex] of fat

In 1 day an adult gains = [tex]5.7315\times 10^{-5} lb[/tex] of fat

Time taken to gain 1 lb fat:

[tex]\frac{1}{5.7315\times 10^{-5}} day=17,447.41 days[/tex]

It will take 17,447.41 days long to gain 1 lb of fat by this person.

Final Answer:

An adult who consumes an excess of 0.2 x 10³ Cal per day, equivalent to 0.8368 x 10³ kJ, will gain 1 lb of fat in approximately 17.5 days, as 1 lb of fat is stored for each 14.6 x 10³ kJ of excess nutritional energy consumed.

Explanation:

An adult consumes approximately 2.2 x 10³ Calories (Cal) per day and burns 2.0 x 10³ Cal per day. To find the excess nutritional energy in kilojoules, we need to subtract the energy burned from the energy consumed and then convert the result from Calories to kilojoules:

Excess energy (Cal) = 2.2 x 10³ Cal - 2.0 x 10³ Cal = 0.2 x 10³ Cal

Excess energy (kJ) = 0.2 x 10³ Cal x 4.184 kJ/Cal = 0.8368 x 10³ kJ

To calculate how long it will take for the adult to gain 1 lb of fat, we divide the amount of kilojoules that corresponds to 1 lb of fat by the daily excess kilojoules:

Days to gain 1 lb = (14.6 x 10³ kJ per 1 lb) / (0.8368 x 10³ kJ/day)

Days to gain 1 lb = 17.4512 days

Therefore, it will take approximately 17.5 days for the adult to gain 1 lb of fat, given the daily excess of 0.2 x 10³ Cal.

A student made an initial 1:5 dilution of protein lysate. Then 2mL of that was added to 8mL of water. Lastly, the student made a 1:20 dilution of the second tube. What is the final dilution of protein lysate.

Answers

Answer:

The final dilution is 1:400

Explanation:

Let's analyze what we are told: we have an initial 1:5 dilution of protein lysate. This means that the initial solution (stock solution) was diluted 5 times. Then, from this dilution the student prepared another dilution taking 2 mL of the first dilution in 8 mL of water. This is the same as saying we took 1 mL of first dilution in 4 mL of water (the ratio is the same), so we now have a second 1:4 dilution of the first dilution (1:5). Finally, the student made a third 1:20 dilution, this means that the second dilution was further diluted 20 times.

So, to calculate the final dilution of protein lysate, we have to multiply all the dilution factors of every dilution prepared: in this case we have a final dilution of 1:20, this means we have a factor dilution of 20. But it was previously diluted 4 times, so we have a factor dilution of 20×4 = 80. However, this dilution was also previously diluted 5 times, so the new dilution factor is 80 × 5 = 400

This means that the final dilution of the compound was diluted a total of 400 times compared to the initial concentration of stock solution.

If you are given sodium acetate and asked to make a 0.15 M acetate buffer and titrate it to a final pH of 3.7, will you have to add acid, base, or nothing in order to achieve the proper pH? Why?

Answers

Answer:

We need add acid to prepare 0.15 acetate buffer with pH 3.7.

Explanation:

As we know that buffer solution is the combination of weak acid with strong base or strong acid with weak base.

We know that CH3COOH is weak acid .Acetate buffer is the combination of weak acid CH3COOH and conjucate base CH3COO- (from salt).

So we have to add acid to achieve the proper final pH value of mixture.We need add acid to prepare 0.15 acetate buffer with pH 3.7.

Air in an internal combustion engine is at 440°F and 150 psia, with a volume of 10 in3 What is the mass of air (in lbm)?

Answers

Answer: The mass of air is 0.00260 lbs.

Explanation:

To calculate the number of moles, we use the equation given by ideal gas equation:

PV = nRT

Or,

[tex]PV=\frac{m}{M}RT[/tex]

where,

P = pressure of the gas = 150 psia = 10.2 atm   (Conversion factor:  1 psia = 0.068 atm)

V = Volume of gas = [tex]10in^3=0.164L[/tex]    (Conversion factor:  [tex]1in^3=0.0164L[/tex] )

m = mass of air = ?

M = Average molar mass of air = 28.97 g/mol

R = Gas constant = [tex]0.0820\text{ L atm }mol^{-1}K^{-1}[/tex]

T = temperature of the gas = [tex]440^oF=499.817K[/tex]  (Conversion factor: [tex](T(K)-273.15)=(T(^oF)-32)\times \frac{5}{9}[/tex]  )

Putting values in above equation, we get:

[tex]10.2atm\times 0.164L=\frac{m}{28.97g/mol}\times 0.0820\text{ L atm }mol^{-1}K^{-1}\times 499.817K\\\\m=1.18g[/tex]

Converting this mass into lbs, we use the conversion factor:

1 lbs = 454 g

So, [tex]1.18g\times \frac{1lbs}{454g}=0.00260lbs[/tex]

Hence, the mass of air is 0.00260 lbs.

Look at sample problem 17.10 in the 8th edition Silberberg book.

The research and development unit of a chemical company is studying the reaction of methane and H2S, two components of natural gas:

CH4 (g) + 2 H2S (g) ⇋ CS2 (g) + 4 H2 (g)

In one experiment, 1.0 mol of CH4, 1.0 mol of CS2, 2.0 mol of H2S, and 2.0 mol of H2 are mixed in a 400. ml vessel at 960°C. At this temperature, Kc = 225.

In which direction will the reaction proceed to reach equilibrium? Enter right, left, or at equilibrium,

If the concentration of methane at equilibrium is 2.0 M, what is the equilibrium concentration of H2? Enter a number to 1 decimal places.

Answers

Answer : The reaction must shift to the product or right to be in equilibrium.  The equilibrium concentration of [tex]H_2[/tex] is 7.0 M

Explanation :

Reaction quotient (Qc) : It is defined as the measurement of the relative amounts of products and reactants present during a reaction at a particular time.

First we have to determine the concentration of [tex]CH_4,H_2S,CS_2\text{ and }H_2[/tex].

[tex]\text{Concentration of }CH_4=\frac{\text{Moles of }CH_4}{\text{Volume of solution}}=\frac{1mol}{400mL}\times 1000=5M[/tex]

[tex]\text{Concentration of }H_2S=\frac{\text{Moles of }H_2S}{\text{Volume of solution}}=\frac{2mol}{400mL}\times 1000=2.5M[/tex]

[tex]\text{Concentration of }CS_2=\frac{\text{Moles of }CS_2}{\text{Volume of solution}}=\frac{1mol}{400mL}\times 1000=2.5M[/tex]

[tex]\text{Concentration of }H_2=\frac{\text{Moles of }H_2}{\text{Volume of solution}}=\frac{2mol}{400mL}\times 1000=5M[/tex]

Now we have to determine the value of reaction quotient (Qc).

The given balanced chemical reaction is,

[tex]CH_4(g)+2H_2S(g)\rightarrow CS_2(g)+4H_2(g)[/tex]

The expression for reaction quotient will be :

[tex]Q_c=\frac{[CS_2][H_2]^4}{[CH_4][H_2S]^2}[/tex]

In this expression, only gaseous or aqueous states are includes and pure liquid or solid states are omitted.

Now put all the given values in this expression, we get

[tex]Q_c=\frac{(2.5)\times (5)^4}{(2.5)times (5)^2}=25[/tex]

Equilibrium constant : It is defined as the equilibrium constant. It is defined as the ratio of concentration of products to the concentration of reactants.

There are 3 conditions:

When [tex]Q>K[/tex] that means product > reactant. So, the reaction is reactant favored.

When [tex]Q<K[/tex] that means reactant > product. So, the reaction is product favored.

When [tex]Q=K[/tex] that means product = reactant. So, the reaction is in equilibrium.

The given equilibrium constant value is, [tex]K_c=225[/tex]

From the above we conclude that, the [tex]Q<K[/tex] that means reactant > product. So, the reaction is product favored that means reaction must shift to the product or right to be in equilibrium.

Now we have to calculate the concentration of [tex]H_2[/tex] at equilibrium.

The given balanced chemical reaction is,

                     [tex]CH_4(g)+2H_2S(g)\rightarrow CS_2(g)+4H_2(g)[/tex]

Initial conc.   2.5            5               2.5          5

At eqm.       (2.5-x)       (5-2x)       (2.5+x)    (5+4x)

The concentration of [tex]CH_4[/tex] at equilibrium = 2.0 M

As we know that, at equilibrium

(2.5-x) = 2.0 M

x = 0.5 M

The concentration of [tex]H_2[/tex] at equilibrium = (5+4x) = 5 + 4(0.5) = 7.0 M

Therefore, the equilibrium concentration of [tex]H_2[/tex] is 7.0 M

Final answer:

The reaction CH4 (g) + 2 H2S (g) ⇋ CS2 (g) + 4 H2 (g) will proceed to the left to reach equilibrium since the reaction quotient Qc is greater than the given Kc. The equilibrium concentration of H2 when the concentration of methane, CH4, at equilibrium is 2.0 M is 7.0 M.

Explanation:

To determine in which direction the reaction CH4 (g) + 2 H2S (g) ⇄ CS2 (g) + 4 H2 (g) will proceed to reach equilibrium, we need to calculate the reaction quotient Qc and compare it with the equilibrium constant Kc. The provided Kc is 225. The initial concentrations are the moles of each substance divided by the volume of the container. Given initial amounts: CH4 = 1.0 mol, H2S = 2.0 mol, CS2 = 1.0 mol, and H2 = 2.0 mol in a 0.4 L container, at 960°C.

To find the concentrations, we divide the moles by the volume (in liters): [CH4] = 1.0 mol/0.4 L = 2.5 M, [H2S] = 2.0 mol/0.4 L = 5.0 M, [CS2] = 1.0 mol/0.4 L = 2.5 M, and [H2] = 2.0 mol/0.4 L = 5.0 M. The reaction quotient Qc is calculated using the expression Qc = [CS2][H2]⁴ / ([CH4][H2S]²). Plugging in the initial concentrations, we get Qc = (2.5 × 5.0⁴) / (2.5 × 5.0²).
As calculated, Qc turns out to be higher than the given Kc, indicating the reaction will shift to the left to reach equilibrium.

When it comes to the equilibrium concentration of H2, the student provided that the concentration of methane (CH4) at equilibrium is 2.0 M. The ratio of H2 to CH4 in the balanced chemical equation is 4:1, so for every 1 M of CH4 that reacts, 4 M of H2 is produced. Thus, if CH4 decreases to 2.0 M from 2.5 M (a decrease of 0.5 M), then H2 would have to increase by 4 times that amount (2.0 M). The equilibrium concentration of H2 would be the initial concentration plus this change: H2(eq) = 5.0 M + 2.0 M = 7.0 M.

2 Which of the substances listed below are:

a metallic elements?
b non-metallic elements?
C compounds?
d mixtures?

Silicon, sea water, calcium, argon, water, air, carbon
monoxide, iron, sodium chloride, diamond, brass,
copper, dilute sulphuric acid, sulphur, oil, nitrogen,
ammonia.

^Put these where they belong.

Answers

Answer:

See explanation

Explanation:

Sea water = a mixture of different substances in water. If the water evaporates, some of those substances remain as salts. It's not a compound because it's a mixture of compounds and substances. An example of a compound is water ( because it has hydrogen atoms and an oxygen atom)

Calcium = Calcium is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because we can find it on the left side of the periodic table, in group 2.  It's an alkaline earth metal, what makes that calcium is a reactive metal.

Argon = Argon is found on the periodic table, so it can't be a mixture or compound. It is a non-metallic element. We can find it in group 18 on the periodic table. Argon is a noble gas, so non-metallic.

Water = a compound because its only made of 2 atoms : oxygen and hydrogen.  Reasons why water is a compound and not a mixture are:

 - The ormation of a compound is a chemical change which is followed by absorption of energy or evolution of energy, in case of water, electricity is required.

- Mixtures can be separated by physical separation techniques ,Water can not be separated into it its elements by physical separation techniques. But by the absorption of chemical energy.

Air = Mixture because it can be separated into different atoms, molecules,..  like oxygen, nitrogen etc. by the physical separation techniques (fractional distillation).

Carbon Monoxide = Carbon Monoxide is not found on the periodic table so it cannot be an element. It's made of 2 elements, this means caron monoxide is a compound. It's not a mixture since the elements cannot be separated by physical separating techniques.

Iron = Iron is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because:

-High melting point

-  Some metals form a dull oxide layer, this explains the shiny luster surface

- Electrical conductivity and thermal conductivity

Sodium chloride = NaCl cannot be found on the periodic table, so it isn't an element. It's a compound because it only has 2 atoms (elements). Those elements cannot be seperated by physical separating techniques, but would require electricity. So it's a compound.

Diamond = is a solid form of the element Carbon.  It's an allotrope of carbon. They have the same physical state but in distinct form. Technically diamond is a non-metallic element. Since it's seen as carbon.

Brass = Brass is a mixture of the elements of copper and zinc. Those elements can be separated by physical techniques.

Copper = Copper is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because:

-High melting point

-  Some metals form a dull oxide layer, this explains the shiny luster surface

- Electrical conductivity and thermal conductivity

Dilute sulphuric acid = This is a mixture. Sulphuric acid is a compound but to dilute it's added in water, what is another compound. So it's a mixture of different compounds.

Sulphur = Can be found in the periodic table so it cannot be a mixture or compound. It's part of the metalloids, therefore, it can be concluded that sulfur is a non-metal. It belongs to the oxygen family.

Oil = Oil is a mixture of hydrocarbon compounds which varies in lengths.

Nitrogen = Nitrogen is found on the periodic table, so it can't be a mixture or compound. It can be found as a gas so it is a non-metallic element.

Ammonia = a compound of nitrogen and hydrogen with the formula NH3. Those elements cannot be separated with physical separating techniques.

An sample of an unknown metal was found in a laboratory. Determining the density of the sample can help identify what type of metal is present in the sample. The sample was determined to have a mass of 27.20 g when placed on a scale. When dropped in water, it increased the volume of the water by 3.46 mL. What is the density of the sample of metal?

Answers

An sample of an unknown metal was found in a laboratory. Determining the density of the sample can help identify what type of metal is present in the sample. The sample was determined to have a mass of 27.20 g when placed on a scale. When dropped in water, it increased the volume of the water by 3.46 mL. What is the density of the sample of metal?
Use appropriate SIG FIGS in the answer.

Zinc reacts with hydrochloric acid according to the reaction equation shown. Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g) How many milliliters of 2.50 M HCl(aq) are required to react with 4.65 g of an ore containing 50.0% Zn(s) by mass? volume: mL

Answers

Answer:

Volume of HCl required = 28.4 mL

Explanation:

[tex]Zn(s) + 2HCl (aq) \rightarrow ZnCl_2(aq) + H_2(g)[/tex]

Mass of zinc ore = 4.65 g

% of zinc in zinc ore = 50 %

So, mass of zinc in zinc ore = 0.50 × 4.65 = 2.325 g

No. of moles of Zn = [tex]\frac{2.325}{65.40} = 0.0355\ mol[/tex]

So, as per the reaction coefficient,

1 mol of zinc reacts with 2 mol of HCl

0.0355 mol of zinc reacts with

                                    = 0.0355 × 2 = 0.071 mol of HCl

Molarity of HCl = 2.50 M

Volume of HCl = [tex]\frac{Moles}{Concentration}[/tex]

[tex]Volume\ of\ HCl = \frac{0.071}{2.50} = 0.0284\ L[/tex]

1 L = 1000 mL

0.0284 L = 1000 × 0.0284 = 28.4 mL

A chemist adds 200.0 mL of a 11.0M silver perchlorate (AgCIO solution to a reaction flask. Calculate the millimoles of silver perchlorate the chemist has added to the flask. Be sure your answer has the correct number of significant digits. mmol OP ?

Answers

Answer:

[tex]n=2.20x10^{3} mmol[/tex]

Explanation:

Hello,

To compute such moles, one must identify that the concentration unit in this problem is molarity, which is defined by:

[tex]M=\frac{n}{V}[/tex]

Since we are inquired to compute the moles, we solve for them as follows:

[tex]n=M*V=11.0mol/L*200.0*\frac{1L}{1000mL}\\n=2.2mol[/tex]

Finally, this value in millimoles turns out into:

[tex]n=2.2mol*\frac{1000mmol}{1mol}\\n=2.20x10^{3} mmol[/tex]

Best regards.

The density of air under ordinary conditions at 25°C is 1.19 g/L. How many kilograms of air are in a room that measures 10.0 ft × 11.0 ft and has an 10.0 ft ceiling? 1 in = 2.54 cm (exactly); 1 L = 103 cm3.

Answers

Answer: The mass of air present in the room is 37.068 kg

Explanation :  Given,

Length of the room = 10.0 ft

Breadth of the room = 11.0 ft

Height of the room = 10.0 ft

To calculate the volume of the room by using the formula of volume of cuboid, we use the equation:

[tex]V=lbh[/tex]

where,

V = volume of the room

l = length of the room

b = breadth of the room

h = height of of the room

Putting values in above equation, we get:

[tex]V=10.0ft\times 11.0ft\times 10.0ft=1100ft^3=31148.53L[/tex]

Conversion used : [tex]1ft^3=28.3168L[/tex]

Now we have to calculate the mass of air in the room.

[tex]Density=\frac{Mass}{Volume}[/tex]

[tex]1.19g/L=\frac{Mass}{31148.53L}[/tex]

[tex]Mass=37066.7507g=37.068kg[/tex]

Conversion used : (1 kg = 1000 g)

Therefore, the mass of air present in the room is 37.068 kg

Answer: There are 37 kg of air in the room.

Explanation:

To calculate the volume of cuboid (room), we use the equation:

[tex]V=lbh[/tex]

where,

V = volume of cuboid

l = length of room = 11 ft

b = breadth of room =  10 ft

h = height of room= 10 ft

Putting values in above equation, we get:

[tex]V=10\times 11\times 10=1100ft^3=1100\times 28.3L=31130L[/tex]  (Conversion factor: [tex]1ft^3=28.3L[/tex]

To calculate mass of a substance, we use the equation:

[tex]\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}[/tex]

We are given:

Density of air = 1.19 g/L

Volume of air = volume of room =  31130 L

Putting values in above equation, we get:

[tex]1.19g/L=\frac{\text{Mass of air}}{31130L}\\\\\text{Mass of air}=37000g=37.0kg[/tex]    (1kg=1000g)

Hence, the mass of air is 37 kg.

Based on the type or types of intermolecular forces, predict the substance in each pair that has the higher boiling point. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer. ResetHelp Given the molecules propane (C3H8) and n-butane (C4H10), Given the molecules propane ( C 3 H 8 ) and n-butane ( C 4 H 10 ) , blank has the higher boiling point mainly due to blank. has the higher boiling point mainly due to Given the molecules propane ( C 3 H 8 ) and n-butane ( C 4 H 10 ) , blank has the higher boiling point mainly due to blank.. Given the molecules diethyl ether (CH3CH2OCH2CH3) and 1-butanol (CH3CH2CH2CH2OH), Given the molecules diethyl ether ( C H 3 C H 2 O C H 2 C H 3 ) and 1-butanol ( C H 3 C H 2 C H 2 C H 2 O H ) , blank has the higher boiling point mainly due to blank. has the higher boiling point mainly due to Given the molecules diethyl ether ( C H 3 C H 2 O C H 2 C H 3 ) and 1-butanol ( C H 3 C H 2 C H 2 C H 2 O H ) , blank has the higher boiling point mainly due to blank..

Answers

Answer:

a) n-butane has a higher boiling point

b) 1-butanol has a higher boiling

Explanation:

Given the molecules, propane (C3H8) and n-butane (C4H10), n-butane has a higher boiling point mainly due to greater molar mass and longer chain (more interactions between each molecule).

Given the molecules, diethyl ether (CH3CH2OCH2CH3) and 1-butanol (CH3CH2CH2CH2OH), 1-butanol has a higher boiling point mainly due to hydrogen bonding forces. The OH group is more electronegative than ether group.

Final answer:

The larger and more complex n-butane has a higher boiling point due to London dispersion forces, while 1-butanol has a higher boiling point due to hydrogen bonding.

Explanation:

Given the molecules, propane (C3H8) and n-butane (C4H10), n-butane has a higher boiling point mainly due to its larger size and increased London dispersion forces, a type of intermolecular force.

London dispersion forces increase with increased molecular size and shape because larger and more complex molecules tend to have more electrons, leading to larger temporary fluctuations in charge distribution.

Given the molecules diethyl ether (CH3CH2OCH2CH3) and 1-butanol (CH3CH2CH2CH2OH), 1-butanol has the higher boiling point mainly due to the presence of hydrogen bonding, another type of intermolecular force. Hydrogen bonding is generally stronger than other types of intermolecular forces, leading to higher boiling points.

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A solution is composed of 85.5 wt% methanol in water. Find the mol fraction of methanol in the solution.

Answers

Answer:

0.7681

Explanation:

Given that the mass percentage of methanol = 85.5 %

which means that 85.5 g of methanol is present in 100 g of the solution.

Thus, mass of water = 100 g - 85.5 g = 14.5 g

The formula for the calculation of moles is shown below:

[tex]moles = \frac{Mass\ taken}{Molar\ mass}[/tex]

Mass of methanol = 85.5 g

Molar mass of methanol = 32.04 g/mol

Moles of methanol = 85.5 g / 32.04 g/mol = 2.6685 moles

Mass of water = 14.5 g

Molar mass of methanol = 18 g/mol

Moles of methanol = 14.5 g / 18 g/mol = 0.8056 moles

So, according to definition of mole fraction:

[tex]Mole\ fraction\ of\ methanol=\frac {n_{methanol}}{n_{methanol}+n_{water}}[/tex]

Applying values as:

[tex]Mole\ fraction\ of\ methanol=\frac {2.6685}{2.6685+0.8056}[/tex]

Mole fraction of methanol in the solution = 0.7681

An AM radio station broadcasts at 1030 kHz , and its FM partner broadcasts at 98.5 MHz .

partA;Calculate the energy of the photons emitted by the AM radio station.

partB;Calculate the energy of the photons emitted by the FM radio station.

partC;Compare the energy of the photons emitted by the AM radio station with the energy of the photons emitted by the FM radio station.

Answers

Final answer:

The energy of the photons emitted by the AM and FM radio stations can be calculated using Planck's equation (E = hf). The calculated energies show that the FM radio station's photons have higher energy than the AM radio station's photons.

Explanation:

To calculate the energy of the photons emitted by radio stations, we use the formula:

E = hf, where E is the energy, h is Planck's constant (6.62607015 × 10⁻³⁴ Js) and f is the frequency.

(For the sake of this calculation, we are going to convert the frequency from kHz and MHz to Hz.)

The AM radio station broadcasts at 1030 kHz, which is equal to 1.03×10⁶ Hz. Substitute the values into the formula: E = (6.62607015 × 10⁻³⁴ Js) × (1.03 × 10⁶ Hz) = 6.825 × 10⁻²⁸ joules.The FM radio station broadcasts at 98.5 MHz, which is equal to 98.5×10^6 Hz. Substitute the values into the formula: E = (6.62607015 × 10⁻³⁴ Js) × (98.5 × 10⁶ Hz) = 6.527 × 10⁻²⁶ joules.

Comparing these energy values, it's clear that the FM radio station's emitted photons have a higher energy than the AM radio station's photons, due to its higher frequency.

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Calculate the amount of heat in kJ that is required to heat 25.0 g of ice from -25 °C to 105 °C in a closed vessel and sketch a heating curve for the process. The specific heat of ice is 2.11 J/(g. "C); 4.18 J/g. "C) for water, 2.00 J/g. "C. AHus for water is 6,01 kJ/mol; AHp for water = 40.67 kJ/mol.

Answers

Answer:

The total amount of heat required for the process is 76.86 KJ

Explanation:

We can divide the process in 5 parts, in which we can calcule each amount of heat required (see attached Heating curve):

(1) Ice is heated from -25ºC to 0ºC. We can calculate the heat of this part of the process as follows. Note that we must convert J in KJ (1 KJ= 1000 J).

Heat (1) = mass ice x Specific heat ice x (Final temperature - Initial Temperature)

Heat (1) =[tex]25 g x 2.11 J/g.ºC x \frac{1 KJ}{1000 J} x (0ºC-(-25º)[/tex]

Heat (1) = 1.32 KJ

(2) Ice melts at ºC (it becomes liquid water). This is heating at constant temperature (ºC), so we use the melting enthalphy (ΔHmelt) and we must use the molecular weight of water (1 mol H₂O = 18 g):

Heat (2) = mass ice x ΔHmelt

Heat (2)= [tex]25 g  x  \frac{6.01KJ} {1 mol H2O} x \frac{1 mol H2O}{18 g}[/tex]

Heat (2)= 8.35 KJ

(3) Liquid water is heated from 0ºC to 100 ºC:

Heat (3)= mass liquid water x Specific heat water x (Final T - Initial T)

Heat (3)= 25 g x 4.18 J/gºC x 1 KJ/1000 J x (100ºC - 0ºC)

Heat (3)= 10.45 KJ

(4) Liquid water evaporates at 100ºC (it becomes water vapor). This is a process at constant temperature (100ºC), and we use boiling enthalpy:

Heat (4)= mass water x ΔH boiling

Heat (4)= 25 g x [tex]\frac{40.67 KJ}{mol H20}[/tex] x [tex]\frac{1 mol H20}{18 g}[/tex]

Heat (4)= 56.49 KJ

(5) Water vapor is heated from 100ºC to 105ºC. We use the specific capacity of water vapor:

Heat (5)= mass water vapor x Specific capacity vapor x (Final T - Initial T)

Heat (5)= 25 g x 2.00 J/g ºC x 1 KJ/1000 J x (105ºC - 100ºC)

Heat (5)= 0.25 KJ

Finally, we calculate the total heat involved in the overall process:

Total heat= Heat(1) + (Heat(2) + Heat(3) + Heat(4) + Heat(5)

Total heat= 1.32 KJ + 8.35 KJ + 10.45 KJ + 56.49 KJ + 0.25 KJ

Total heat= 76.86 KJ

For the following reaction, calculate how many grams of each product are formed when 4.05 g of water is used.
2 H20 -----> 2 H2 + O2

Answers

Answer: The mass of hydrogen gas and nitrogen gas produced is 0.45 g and 3.15 g respectively.

Explanation:

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]      .....(1)

Given mass of water = 4.05 g

Molar mass of water = 18 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of water}=\frac{4.05g}{18g/mol}=0.225mol[/tex]

For the given chemical reaction:

[tex]2H_2O\rightarrow 2H_2+O_2[/tex]

For hydrogen:

By Stoichiometry of the reaction:

2 moles of water is producing 2 moles of hydrogen gas

So, 0.225 moles of water will produce = [tex]\frac{2}{2}\times 0.225=0.225mol[/tex] of hydrogen gas.

Now, calculating the mass of hydrogen gas by using equation 1, we get:

Moles of hydrogen gas = 0.225 mol

Molar mass of hydrogen gas = 2 g/mol

Putting values in equation 1, we get:

[tex]0.225mol=\frac{\text{Mass of hydrogen gas}}{2g/mol}\\\\\text{Mass of hydrogen gas}=0.45g[/tex]

For nitrogen:

By Stoichiometry of the reaction:

2 moles of water is producing 1 mole of nitrogen gas

So, 0.225 moles of water will produce = [tex]\frac{1}{2}\times 0.225=0.1125mol[/tex] of nitrogen gas.

Now, calculating the mass of nitrogen gas by using equation 1, we get:

Moles of nitrogen gas = 0.1125 mol

Molar mass of nitrogen gas = 28 g/mol

Putting values in equation 1, we get:

[tex]0.1125mol=\frac{\text{Mass of nitrogen gas}}{28g/mol}\\\\\text{Mass of nitrogen gas}=3.15g[/tex]

Hence, the mass of hydrogen gas and nitrogen gas produced is 0.45 g and 3.15 g respectively.

Write chemical formulas for compounds containing each of the following. One nitrogen atom for every three chlorine atoms.

Answers

Answer:

NCL3

Explanation:

NCL3

- nitrogen trichloride.

The chemical formula for a compound containing one nitrogen atom for every three chlorine atoms is NCl₃.

The chemical formula NCl₃ represents a compound consisting of one nitrogen atom and three chlorine atoms. In this formula, "N" represents nitrogen, and "Cl" represents chlorine. The subscript "3" indicates that there are three chlorine atoms bonded to each nitrogen atom in the compound.

This arrangement reflects the stoichiometry of the compound, specifying the relative ratios of the elements. Chemical formulas provide a concise way to describe the composition of substances, allowing scientists to understand the types and quantities of atoms present in a compound.

NCl₃, nitrogen trichloride, is a covalent compound with notable chemical properties, and its formula encapsulates the balanced proportion of nitrogen and chlorine within its molecular structure.

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How much 0.2M HCl can be made from 5.0mL of a 12.0M
HClSolution?

Answers

Answer: The volume of 0.10 M NaOH required to neutralize 30 ml of 0.10 M HCl is, 30 ml.

Explanation:

According to the dilution law,

[tex]M_1V_1=M_2V_2[/tex]

where,

[tex]M_1[/tex] = molarity of stock [tex]HCl[/tex] solution = 12.0 M

[tex]V_1[/tex] = volume of stock [tex]HCl[/tex]solution = 5.0 ml

[tex]M_2[/tex] = molarity of dilute [tex]HCl[/tex] solution = 0.2 M

[tex]V_2[/tex] = volume of  dilute [tex]HCl[/tex]  solution = ?

Putting in the values we get:

[tex](12.0M)\times 5.0=0.2\times V_2[/tex]

[tex]V_2=300ml[/tex]

Therefore, 300 ml of 0.2M HCl can be made from 5.0mL of a 12.0M [tex]Hcl[/tex] solution.

A large pot (10 kg) of beef stew is left out on the kitchen counter to cool. The rate of cooling, in kJ/min, equals 1.955 (T-25), where T is the temperature of the stew in degrees Celsius. The heat capacity of the stew is 4 kJ/kg-C. If the stew initially is at 90 C, how long does it take to cool to 40 C? Round off your answer to the nearest minute.

Answers

Answer:

16 minutes

Explanation:

First, we need to calculate the amount of heat needed to cool the beef stew:

Q = mcΔT

Where m is the mass, c is the heat capacity and ΔT is the variation of the temperature.

Q = 10x4x(40 - 90)

Q = -2000 kJ

So, the beef stew needs to lost 2000 kJ to cool.

With the initial temperature at 90ºC, the rate of cooling(r) will be:

r = 1.955x(90 - 25)

r = 127.075 kJ/min

So, to lose 2000 kJ, will be necessary:

t = Q/r

t = 2000/127.075

t = 16 minutes

Why was 1,2 dichlorobenzene used as the solvent for the diels alder reaction we performed in the lab?

Because it smells good since it is aromatic

Because it is easy to remove from the product since it is quite volatile

Because it can kill some bacteria in the reactants since it is toxic

because the co elimination part of the reaction needs high temp and a high boiling point solvent such as 1,2 dichlorobenzene bp 179C has to be used

Answers

Answer:

1,2 dichlorobenzene was used as the solvent for the diels alder reaction: because the co elimination part of the reaction needs high temp and a high boiling point solvent such as 1,2 dichlorobenzene

Explanation:

Diels-Alder Reaction is a useful synthetic tool to prepare cyclohexane rings. It is a process, which occurs in a single step that consists of a cyclic redistribution of its electrons. The two reagents are bond together through a cyclic transition state in which the two new C-C bonds are formed at the same time. For this to occur, most of the time, it is necessary a high temperature and high-pressure conditions. Since 1,2 dichlorobenzene has a boiling point of 180ºC is a good solvent for this type of reactions.

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