Answer:
[tex]578.2\times 10^{-6}[/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:
0.00057824 can be written as [tex]578.24\times 10^{-6}[/tex]
Answer upto 4 significant digits = [tex]578.2\times 10^{-6}[/tex]
a 50-g sample contains 32.1 g of oxygen 2 g of hydrogen and 15.9 g of carbon
Answer:
i need more to solve this
Explanation:
Options for full question:
(A) % oxygen is 32.1%
(B) % hydrogen is 4%
(C) total percent composition of all elements is approximately 100%
(D) % carbon is 15.9%
Answer:
Options B and C
Explanation:
Information Given;
Mass of sample - 50g
Mass of Oxygen - 32.1g
Mass of Hydrogen - 2g
Mass of Carbon - 15.9g
The percentage composition of an element in a compound is the mass percentage of the element present in the compound. It tells the mass percentage of each element present in a compound.
The formular is given as;
Percentage composition = (Mass of element / Mass of compound) * 100
For oxygen;
Percentage Composition = (32.1 / 50) * 100 = 0.642 * 100= 64.2%
For Hydrogen;
Percentage Composition = (2 / 50) * 100 = 0.04 * 100= 4%
For Carbon;
Percentage Composition = (15.9 / 50) * 100 = 0.318 * 100= 31.8%
Total percentage composition of all elements = 4% + 31.8% + 64.2% = 100%
Based on this,
Option A is incorrect
Option B is Correct.
Option C is Correct.
Option D is incorrrect
Given a water solution that contains 1.704 kg of HNO:/kg H:O and has a specific gravity of 1.382 at 20 °C, express the composition in the following ways: (a) Weight percent HNO (b) Pounds HNO3 per cubic foot of solution at 20 °c (c) Molarity (gmoles of HNOs per liter of solution at 20 °C)
Answer:
a) 63,0%
b) 54,4 Pounds HNO₃ per cubic foot of solution
c) 13,8 M
Explanation:
a) Weight percent is the ratio solute:solution times 100:
[tex]\frac{1,704 kg HNO_3}{2,704 kg Solution}[/tex] = 63,0%
b) Pounds HNO₃ per cubic foot of solution at 20 °c
Pounds HNO₃:
1,704 kg [tex]\frac{2,20462 pounds}{1 kg}[/tex] = 3,7567 pounds
Cubic foot:
2,704 kg [tex]\frac{1 L}{1,382 kg}[/tex]x[tex]\frac{1 cubic foot }{28,3168 L}[/tex] = 0,069 ft³
Thus:[tex]\frac{3,7567 pounds}{0,069ft^3} =[/tex] = 54,4 Pounds HNO₃ per cubic foot of solution
c) Moles of HNO₃:
1704 g HNO₃ [tex]\frac{1 mol HNO_3}{63,01 g }[/tex] = 27,04 moles
Liters of solution:
2,704 kg [tex]\frac{1 L}{1,382 kg}[/tex] = 1,96 L of solution
Molarity:
[tex]\frac{27,04 mol}{1,96 L}[/tex] = 13,8 M
Final answer:
The composition of the solution can be expressed as 63.02 wt% HNO3, 54.28 lb HNO3/ft3, and a molarity of 14.2 M at 20 °C.
Explanation:
To express the composition of a water solution with 1.704 kg of HNO3 per kg of H2O and a specific gravity of 1.382 at 20 °C, we can calculate the following:
Weight Percent HNO3
Weight percent (wt%) is calculated as the mass of the solute divided by the total mass of the solution, multiplied by 100. For 1.704 kg HNO3 in 1 kg of water, the total mass of the solution is 1.704 kg + 1 kg = 2.704 kg. The weight percent HNO3 is then ((1.704 kg) / (2.704 kg)) × 100 = 63.02 wt%.
Pounds HNO3 per Cubic Foot of Solution at 20 °C
Firstly, we need to convert the specific gravity to density in g/mL: 1.382 (Specific Gravity) × 1.000 g/mL (density of water) = 1.382 g/mL. To find the density in lb/ft3, we multiply by 62.43 lb/ft3 which is the conversion factor from g/mL to lb/ft3. Then, multiply the density of the solution by the weight percent of HNO3 to find pounds HNO3 per cubic foot of solution: (1.382 g/mL) × (62.43 lb/ft3) × (63.02%) = 54.28 lb HNO3/ft3.
Molarity of HNO3 at 20 °C
Using the density of the concentrated HNO3 solution, 1.42 g/mL, and the given formula for molarity which is Molarity = [(%) (d)/ (Mw)] × 10, we substitute the values: Molarity = [(63.02) (1.42 g/mL) / (63.01)] × 10 = 14.2 M.
Normally carbon forms how many and what type of bonds?
Answer:
Carbon generally forms four covalent chemical bonds.
Explanation:
Carbon is a chemical element that belongs to group 14 of the periodic table and has atomic number 6. It is a member of the p-block and is nonmetallic in nature.
The ground-state electronic configuration of carbon atom is 1s²2s²2p². Thus, it has 4 valence electrons and is said to be tetravalent.
Therefore, carbon generally forms four covalent chemical bonds.
What is the overall (X-fold) dilution of 4 serial 2-fold dilutions?
Answer:
16-fold dilution.
Explanation:
A serial dilution is any dilution where the concentration decrease by the same quantity in each successive step. So, for a 2-fold dilution, the concentration decrease 1/2, it means that if we have a sample with 10 M of concentration, after a 2-fold dilution it will be 5 M. For the next step it will be 1/2 of 5= 2.5 M, and successively.
Then, we just multiply the factor for each dilution. After 4 serial dilutions:
1/2 x 1/2 x 1/2 x 1/2 = 1/16
So, it would be a 16-fold dilution in the end.
If you have 16 g of manganese (II) nitrate tetrahydrate, how much water is required to prepare 0.16 M solution from this amount of salt? OL 0 0.01 L the task is impossible, as manganese nitrate is insoluble in water O 0.10 L 398 ml
Answer: The volume of water required is 398 mL
Explanation:
To calculate the molarity of solution, we use the equation:
[tex]\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}[/tex]
We are given:
Mass of solute (manganese (II) nitrate tetrahydrate) = 16 g
Molar mass of manganese (II) nitrate tetrahydrate = 251 g/mol
Molarity of solution = 0.16 M
Putting values in above equation, we get:
[tex]0.16M=\frac{16g\times 1000}{251g/mol\times \text{Volume of solution}}\\\\\text{Volume of solution}=398mL[/tex]
Hence, the volume of water required is 398 mL
The unit conversion between rankine and kelvin is (linear, exponential, quadratic, none of the above)?
The unit conversion between degrees Celsius and degrees Fahrenheit is (linear, exponential, quadratic, none of the above)?
Answer:
Unit conversion between Rankine and Kelvin is linear.
Unit conversion between degree Celsius and degree Fahrenheit is linear.
Explanation:
Relation between rankine and Kelvin is
[tex]R\ =\ \dfrac{9}{5}\ K[/tex]
So, the plot between Rankine and Kelvin is a straight line with zero intercept and has a slope having value [tex]\dfrac{9}{5}[/tex].
Relation between degrees Celsius and degrees Fahrenheit is given by
[tex]^{\circ}C\ =\ \dfrac{5}{9}\ (^{\circ}F\ -\ 32)[/tex]
So, the plot between degrees Celsius and degrees Fahrenheit is a straight line with slope [tex]\dfrac{5}{9}[/tex] and negative intercept of [tex]\dfrac{160}{9}[/tex].
why diamond has a very high melting point than aluminium??
A protein has a binding site for a single ligand with a A.G-16.7 KJ/mol at 298 K. What is Keg for this reaction?
Explanation:
The given data is as follows.
[tex]\Delta_{r} G[/tex] = -16.7 kJ/mol = [tex]-16.7 \times 10^{3}[/tex], T = 298 K
R = 8.314 J/mol K, [tex]K_{eq}[/tex] = ?
Relation between [tex]\Delta_{r} G[/tex] and [tex]K_{eq}[/tex] is as follows.
[tex]\Delta_{r} G[/tex] = [tex]-RT ln K_{eq}[/tex]
Hence, putting the values into the above equation as follows.
[tex]\Delta_{r} G[/tex] = [tex]-RT ln K_{eq}[/tex]
[tex]-16.7 \times 10^{3} J/mol[/tex] = [tex]-8.314 J/mol K \times 298 K ln K_{eq}[/tex]
[tex]ln K_{eq}[/tex] = [tex]\frac{-16.7 \times 10^{3} J/mol}{-8.314 J/mol K \times 298 K}[/tex]
= 6.740
[tex]K_{eq}[/tex] = antilog (6.740)
= 846
Thus, we can conclude that [tex]K_{eq}[/tex] for given values is 846.
How many grams of solid Ca(OH)2 (74.1 g/mol) are required to make 500 ml of a 3 M solution?
Answer:
111.15 g are required to prepare 500 ml of a 3 M solution
Explanation:
In a 3 M solution of Ca(OH)₂ there are 3 moles of Ca(OH)₂ per liter solution. In 500 ml of this solution, there will be (3 mol/2) 1.5 mol Ca(OH)₂.
Since 1 mol of Ca(OH)₂ has a mass of 74.1 g, 1.5 mol will have a mass of
(1.5 mol Ca(OH)₂ *(74.1 g / 1 mol)) 111.15 g. This mass of Ca(OH)₂ is required to prepare the 500 ml 3 M solution.
A 0.1375 g sample of solid magnesium is burned in
aconstant-volume bomb calorimeter that has a heat capacity of3024
J/ oC. The temperature increases by 1.126oC.
Calculate the heat given off by burning Mg, inkJ/g and in
kJ/mol.
Answer:
24.76 kJ/g
844.8 kJ/mol
Explanation:
The heat produced by the burning of the solid magnesium is equal to the heat absorbed by the calorimeter, which causes its temperature to increase.
First, we calculate the heat absorbed by the calorimeter, where C is the heat capacity and Δt is the temperature change.
Q = CΔt = (3024 J·°C⁻¹)(1.126 °C) = 3405 J
This is the same amount of heat that was produced by burning the magnesium
Now we can calculate the heat produced per gram of magnesium:
(3405 J)(1 kJ/1000 J) / (0.1375 g) = 24.76 kJ/g
We can convert grams to moles using the atomic weight of Mg (24.305 g/mol).
(24.76 kJ/g)(24.305 g/mol) = 844.8 kJ/mol
A solution of HNO3HNO3 is standardized by reaction with pure sodium carbonate. 2H++Na2CO3⟶2Na++H2O+CO2 2H++Na2CO3⟶2Na++H2O+CO2 A volume of 27.71±0.05 mL27.71±0.05 mL of HNO3HNO3 solution was required for complete reaction with 0.9585±0.0007 g0.9585±0.0007 g of Na2CO3Na2CO3 , (FM 105.988±0.001 g/mol105.988±0.001 g/mol ). Find the molarity of the HNO3HNO3 solution and its absolute uncertainty.
Answer:
(0,653±0,002) M of HNO₃
Explanation:
The reaction of standarization of HNO₃ with Na₂CO₃ is:
2 HNO₃ + Na₂CO₃ ⇒ 2 Na⁺ + H₂O + CO₂ + 2NO₃⁻
To obtain molarity of HNO₃ we need to know both moles and volume of this acid. The volume is (27,71±0,05) mL and to calculate the moles it is necessary to obtain the Na₂CO₃ moles and then convert these to HNO₃ moles, thus:
0,9585 g of Na₂CO₃ × ( 1 mole / 105,988 g) =
9,043×10⁻³ mol Na₂CO₃ × ( 2 moles of HNO₃ / 1 mole of Na₂CO₃) = 1,809×10⁻² moles of HNO₃
Molarity is moles divide liters, thus, molarity of HNO₃ is:
1,809×10⁻² moles / 0,02771 L = 0,6527 M of HNO₃
The absolute uncertainty of multiplication is the sum of relative uncertainty, thus:
ΔM = 0,6527M× (0,0007/0,9585 + 0,001/105,988 + 0,05/27,71) =
0,6527 M× 2,54×10⁻³ = 1,7×10⁻³ M
Thus, molarity of HNO₃ solution and its absolute uncertainty is:
(0,653±0,002) M of HNO₃
I hope it helps!
Which radioactive emission has the smallest (least) mass? Question options:
A) Positron
B) Alpha
C) All have equal mass
D) Gamma
E) Beta
Answer:
The answer is D. gamma rays
Explanation:
A radioactive atom can have three different types of emission:
alpha particles (α) = they have a mass of 4 amu and they have a very low penetrating power.
Beta particles (β) = they have 5x[tex]10^{-4}[/tex] amu and they have an intermediate penetrating power
Gamma rays (γ) = they are not particles basically just energy so its mass is ≈ 0 and its penetrating power is higher
For this reason Gamma emissions (γ) has the smallest mass value.
Among the options provided, the gamma photon in radioactive emissions has the smallest mass (zero mass), which means that it's the correct answer to the question. Gamma radiation is energy emission without a corresponding mass.
Explanation:In the context of radioactive emissions, each type has a different mass. The alpha particle is the heaviest and is comprised of two neutrons and two protons. Beta particles, which are electrons (or positrons in the case of beta-plus decay), have a smaller mass. Positrons have the same mass as electrons but with a positive charge.
However, the gamma photon, which is a type of electromagnetic radiation, has no rest mass at all. So, out of the given options, the gamma ray has the smallest (in this case, zero) mass. This is an example of energy being emitted without a corresponding mass in a radioactive process, which often occurs when the remaining nucleus is in an excited state post decay and moves to a lower energy level by emitting a gamma photon.
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Many elements combine with hydrogen(valence = 1) to give compounds called hydrides. Use the position of an element in the periodic table to deduce its valence. Write formulas for these hydrides without using subscripts, for example XH3. If no hydride forms, write "none". What is the formula of the hydride formed by sulfur? What is the formula of the hydride formed by potassium ? ||
Answer:
Explanation:
Use the position of an element in the periodic table to deduce its valence.
The periodic table is a table that groups elements based on their periodic functions. A group is a vertical arrangement of elements. The group number shows the number of elements in the outer shell of the atoms.
The groups runs from 1 to 8. On the periodic table, elements that has more than 4 electrons in their outermost shell will have a valency of 8 less than the number of outermost electrons.
Write formulas for these hydrides without using subscripts, for example XH3. If no hydride forms, write "none".
for group I : NaH, KH,
group II : MgH2, CaH2,
group III: BH3, AlH3
Group 8 do not form hydrides because of their inertness.
What is the formula of the hydride formed by sulfur?
the hydride of sulfur is H₂S
What is the formula of the hydride formed by potassium ?
the hydride of potassium is KH
Final answer:
The formula of the hydride formed by sulfur is H2S, while the formula for the hydride formed by potassium is KH, based on the valence of sulfur and potassium corresponding to their positions in the periodic table.
Explanation:
When determining the formulas for hydrides, the valence of the non-hydrogen element is crucial. Sulfur, which has a valence of 2, forms a hydride by combining with two hydrogen atoms, giving us the formula H2S. In contrast, potassium belongs to the alkali metals with a valence of 1, thus it combines with one hydrogen atom to form a hydride, resulting in the formula KH.
The periodic table helps us understand these valences due to an element's group number. Sulfur, located in group 16, typically forms compounds where it has two bonding sites, as seen with its hydride, hydrogen sulfide. Potassium, found in group 1, forms compounds by donating a single electron, resulting in a 1:1 ratio with hydrogen in potassium hydride.
What is the formula for aluminum nitrite ?
Answer: The chemical formula for aluminium nitrite is [tex]Al(NO_2)_3[/tex]
Explanation:
The given compound is formed by the combination of aluminium and nitrite ions. This is an ionic compound.
Aluminium is the 13th element of periodic table having electronic configuration of [tex][Ne]3s^23p^1[/tex].
To form [tex]Al^{3+}[/tex] ion, this element will loose 3 electrons.
Nitrite ion is a polyatomic ion having chemical formula of [tex]NO_2^{-}[/tex]
By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.
So, the chemical formula for aluminium nitrite is [tex]Al(NO_2)_3[/tex]
The formula for aluminum nitrite is Al(NO3)3.
The formula for aluminum nitrite is Al(NO2)3.
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The heat capacity of chloroform (trichloromethane,CHCl3)
in the range 240K to 330K is given
byCpm/(JK-1mol-1) = 91.47
+7.5x10-2(T/K). In a particular experiment,
1.0molCHCl3 is heated from 273K to 300K. Calculate the
changein molar entropy of the sample.
Answer : The change in molar entropy of the sample is 10.651 J/K.mol
Explanation :
To calculate the change in molar entropy we use the formula:
[tex]\Delta S=n\int\limits^{T_f}_{T_i}{\frac{C_{p,m}dT}{T}[/tex]
where,
[tex]\Delta S[/tex] = change in molar entropy
n = number of moles = 1.0 mol
[tex]T_f[/tex] = final temperature = 300 K
[tex]T_i[/tex] = initial temperature = 273 K
[tex]C_{p,m}[/tex] = heat capacity of chloroform = [tex]91.47+7.5\times 10^{-2}(T/K)[/tex]
Now put all the given values in the above formula, we get:
[tex]\Delta S=1.0\int\limits^{300}_{273}{\frac{(91.47+7.5\times 10^{-2}(T/K))dT}{T}[/tex]
[tex]\Delta S=1.0\times [91.47\ln T+7.5\times 10^{-2}T]^{300}_{273}[/tex]
[tex]\Delta S=1.0\times 91.47\ln (\frac{T_f}{T_i})+7.5\times 10^{-2}(T_f-T_i)[/tex]
[tex]\Delta S=1.0\times 91.47\ln (\frac{300}{273})+7.5\times 10^{-2}(300-273)[/tex]
[tex]\Delta S=8.626+2.025[/tex]
[tex]\Delta S=10.651J/K.mol[/tex]
Therefore, the change in molar entropy of the sample is 10.651 J/K.mol
What is the theoretical Van’t Hoff factor for the following substances: HCL & ethanol (CH3CH2OH)
Answer:
i=2 for HCl and i=1 for ethanol
Explanation:
Hello,
Since the hydrochloric acid is composed by sodium and chloride ions which are completely dissociated, two types of ions are present, that's why i becomes 2.
On the other hand, as long as the ethanol doesn't present dissociation in aqueous solution, the Van't Hoff factor becomes 1.
Best regards.
What is the wavenumber of the radiation emitted when a hydrogen
atom makes a transition corresponding to a change in energy of
1.634 x 10-18 J?
Answer: Wavenumber of the radiation emitted is [tex]0.08\times 10^{8}m^{-1}[/tex]
Explanation:
The relationship between wavelength and energy of the wave follows the equation:
[tex]E=\frac{hc}{\lambda}[/tex]
where,
E = energy of the radiation = [tex]1.634\times 10^{-18}J[/tex]
h = Planck's constant = [tex]6.626\times 10^{-34}Js[/tex]
c = speed of light = [tex]3\times 10^8m/s[/tex]
[tex]\lambda[/tex] = wavelength of radiation = ?
Putting values in above equation, we get:
[tex]1.634\times 10^{-18}J=\frac{(6.626\times 10^{-34}Js)\times (3\times 10^8m/s)}{\lambda}\\\\\lambda=12.16\times 10^{-8}m[/tex]
[tex]\bar {\nu}=\frac{1}{\lambda}=\frac{1}{12.16\times 10^{-8}}=0.08\times 10^{8}m^{-1}[/tex]
Thus wavenumber of the radiation emitted is [tex]0.08\times 10^{8}m^{-1}[/tex]
Give the names for each of the elements between atomic numbers 1 and 86 that has a symbol starting with "C".
Identify the family each element belongs to. If the element does not belong to a family, identify it as a metal or non-metal.
2. In your own words, define the following terms. a. Element b. Atom c. Molecule d. Compound 3. How many oxygen atoms are in one molecule (or formula unit) of each of the following compounds? NO3 Al(OH)3 Ca(NO3)2 Ba(OCN)2
Explanation:
1)
Carbon with atomic number 6. The symbol of carbon is C.It belongs to non metals.Chlorine with atomic number of 17. The symbol of chlorine is Cl.It belongs to non metals.Calcium with atomic number 20. The symbol of calcium is Ca. It belongs to metals.Chromium with atomic number 24. The symbol of chromium is Cr. It belongs to metals.Cobalt with atomic number of 27. The symbol of cobalt is Co. It belongs to metals.Copper with atomic number of 29. The symbol of copper is Cu. It belongs to metals.Cadmium with atomic number of 48. The symbol of cadmium is Cd. It belongs to metals.Cesium with atomic umber of 55.The symbol of cesium is Cs. It belongs to metals.Cerium with atomic number of 58. the symbol for cerium in Ce. It belongs to metals.2)
Element are those substance which can not be split into simpler substance.they are made up of single atom.
Atom is the structural unit of the matter and smallest component of an element.
Molecules are group of atoms bonded together. The atom boned can be of more than one type.
Compounds are group of atoms of different elements bonded together.
3) Oxygen atoms in one molecule of following compounds:
a) [tex]NO_3[/tex]
1 × 3 = 3
There 3 oxygen atoms in the 1 molecule of [tex]NO_3[/tex].
b) [tex]Al(OH)_3[/tex]
3 × 1 = 3
There 3 oxygen atoms in the 1 molecule of [tex]Al(OH)_3[/tex].
c) [tex]Ca(NO_3)_2[/tex]
2 × 3 = 6
There 6 oxygen atoms in the 1 molecule of [tex]Ca(NO_3)_2[/tex].
d) [tex]Ba(OCN)_2[/tex]
2 × 1 = 2
There 6 oxygen atoms in the 1 molecule of [tex]Ba(OCN)_2[/tex].
Picture this in your mind as you read it: You weigh an empty, clean, dry beaker on the balance (scale). It weighs 32.15 grams. You are instructed to measure out 2.0 grams of solid X and put it in the beaker you just weighed. Using weighing paper, you weigh out 2.0 grams of solid X and carefully transfer it into the beaker. You now weigh the beaker WITH the solid in it and get a mass of 34.40 grams. What is the weight of the solid, using the correct number of significant figures? 2.0 grams, just as you weighed it before putting it in the beaker. 2.00 grams, using the correct number of significant figures. The mass is 34.40 g -32.15 g -2.3 grams The mass is 34.40 g -32.15 g -2.25 grams
Answer:
2.25 g
Explanation:
The mass of the solid X must be the total mass (beaker + solid X) less than the mass of the beaker. Then:
mass of the solid X = 34.40 - 32.15
mass of the solid X = 2.25 g
The difference of 0.25 g must occur for several problems: an incorrect weight in the balance, the configuration of the balance, the solid can be hydrophilic and absorbs water, and others.
Assuming steam to be an ideal gas, calculate its specific volume and density at a pressure of 90 lb/in2 and a temperature of 650F Compare your answer using data from the steam tables (appendix of your textbook). Problem 2 (25 points). Find the mass of air in a closed chamber measuring 35ft by 20ft by 10ft, when the pressure is 17 lb/in? and the temperature is 75F, assuming air to be an ideal gas.
Answer:
1) Sv = 0.4584 m³/Kg...assuming steam as an ideal gas
% deviation from the values in the steam tables
⇒ % dev = 45 %
2) mass air = 272.617 Kg; assuming air to be an ideal gas
Explanation:
ideal gas:
PV = RTn
molar volume:
⇒ V/n = RT/P
∴ P = 90 psi * ( 0.06895 bar/psi ) = 6.2055 bar
∴ T = 650 F = 343.33 °C = 616.33 K
∴ R = 0.08314 bar.L/mol.K
⇒ V/n = (( 0.08314 )*(616.33 K )) / 6.2055 bar
⇒ V/n = 8.2574 L/mol * ( m³/1000L ) = 8.2574 E-3 m³/mol
specific volume ( Sv ):
∴ Mw = 18.01528 g/mol
⇒ Sv = 8.2574 E-3 m³/mol * ( mol / 18.01528 g ) * ( 1000 g/Kg )
⇒ Sv = 0.4584 m³/Kg
steam table:
∴ P = 6.2055 bar ≅ 6 bar → Sv = 0.3157 m³/Kg
⇒ % deviation = (( 0.4584 - 0.3157 ) / 0.3157) * 100
⇒ % dev = 45.2 %; significant value, assuming steam to be a ideal gas
2) mass air, assuming ideal gas:
∴ V = 20ft * 35ft * 10ft = 7000ft³ * ( 28.3168 L/ft³ ) = 198217.6 L
∴ P = 17 psi * ( 0.06895 bar/psi ) = 1.172 bar
∴ T = 75 °F = 23.89 °C = 296.89 K
∴ R = 0.08314 bar.L/K.mol
⇒ n air = PV/RT = (( 1.172 )*( 198217.6 )) / (( 0.08314 )*( 296.89 ))
⇒ n air = 9411.616 mol air
∴ Mw air = 28.966 g/mol
⇒ mass air = 9411.616 mol * ( 28.966 g/mol ) = 272616.892 g = 272.617 Kg
Order the following elements based upon their electronegativity, highest to lowest: carbon, flourine, hydrogen, nitrogen, oxygen, and sodium.
Answer:
The correct order is: Fluorine; Oxygen; Nitrogen; Carbon; Hydrogen; Sodium.
Explanation:
The electronegativity in the periodic table increases to the right in a period and up in a group. We can figure out the electronegativity of each element according to its electron configuration:
Carbon: [He] [tex]2s^{2} 2p^{2}[/tex]
Fluorine: [He] [tex]2s^{2} 2p^{5}[/tex]
Hydrogen: [tex]1s^{1}[/tex]
Nitrogen: [He] [tex]2s^{2} 2p^{3}[/tex]
Oxygen: [He] [tex]2s^{2} 2p^{4}[/tex]
Sodium: [Ne] [tex]3s^{1} [/tex]
The period of a chemical element is given by the last energy level of electron configuration.
The group of a chemical element is given by the amount of electrons in the last energy level of electron configuration.
Therefore,
Carbon: Period 2 Group 4
Fluorine: Period 2 Group 7
Hydrogen: Period 1 Group 1
Nitrogen: Period 2 Group 5
Oxygen: Period 2 Group 6
Sodium: Period 3 Group 1
Electronegativity increases when the number of the group increases.
Electronegativity increases when the number of the period decreases.
In conclusion, Fluorine has the greatest number of group and Sodium has the lowest number of group (also it has a greater number of period than hydrogen, so it is less electronegative than hydrogen)
F>O>N>C>H>Na
. Does each of these describe a physical change or a chemical change? Explain a. The moth balls gradually vaporize in a closet. Hydrofluoric acid attacks class, and is used to etch calibrations marks on glass laboratory utensils A French chef making a sauce with brandy is able to burn of the alcohol from the brandy leaving just the brandy flavoring d. Chemistry majors sometimes et holes in the cotton jeans they wear to lab, because of acid spills A piece of egg boiled in water for 20 minutes
Answer:
a. The mothballs gradually vaporize in a closet. Physical change
b. Hydrofluoric acid attacks glass, and is used to etch calibrations marks on glass laboratory utensils. Chemical change
c. A French chef making a sauce with brandy is able to burn of the alcohol from the brandy leaving just the brandy flavoring. Chemical change
d. Chemistry majors sometimes et holes in the cotton jeans they wear to lab, because of acid spills. Chemical change
e. A piece of egg boiled in water for 20 minutes. Chemical change
Explanation:
In a physical change, there is no change in the chemical composition of the substance, the change is only on the physical properties. For example, state changes (a).
In a chemical change instead, usually there is a combination of two or more substances that combine to form a new one different from the originals. For example, chemical reactions like combustion (c) or protein denaturalization (e). The attacking of hydrofluoric acid to glass (b) or the acid pill attacking cotton are chemical reactions too (d).
Physical change or a chemical change are given as:
a. The moth balls gradually vaporize in a closet -physical change.
b. Hydrofluoric acid attacks glass and is used to etch calibration marks on glass laboratory utensils-chemical change.
c. A French chef making a sauce with brandy is able to burn off the alcohol from the brandy, leaving just the brandy flavoring- a chemical change.
d. Chemistry majors sometimes etch holes in the cotton jeans they wear to the lab because of acid spills- physical change.
A piece of egg boiled in water for 20 minutes- chemical change.
a. In a closet, moth balls progressively vaporise: This represents a physical transformation. The moth balls sublimate, going straight from a solid state to a gaseous state, undergoing a phase change from a solid to a gas.
b. Glass is attacked by hydrofluoric acid, which is also used to etch calibration marks on glass laboratory utensils: This refers to a chemical transformation. The glass and hydrofluoric acid interact, causing a chemical reaction that etches the surface of the glass.
c. A French cook who uses brandy in a sauce can burn out the alcohol, leaving only the brandy flavouring: This explains a chemistry alteration. Alcohol is burned off through a chemical reaction, specifically alcohol combustion, which transforms ethanol (alcohol) into carbon dioxide and water vapour.
d. Because of acid spills, chemistry majors occasionally etch holes in the cotton pants they wear to the lab: This sentence depicts a physical alteration. The fibres in the jeans melt or break down as a result of acid spills, creating holes.
e. A chemical change is described by a piece of egg that was boiled in water for 20 minutes. The denaturation of proteins and the coagulation of the egg white are two distinct chemical reactions that occur inside the egg as a result of boiling.
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One particular super red giant star has a surface temperature of 2,822 K. What is the wavelength (in nm) of the spectral maximum in the emission of light by this star?
Answer: [tex]1027nm[/tex]
Explanation:
Using Weins displacement law:
[tex]\lambda_{max}=\frac{b}{T}[/tex]
where [tex]\lambda_{max}[/tex] = wavelength
b = constant =[tex]2898\micro mK[/tex]
T = Temperature in Kelvin = 2822 K
Putting the values we get:
[tex]\lambda _{max}=\frac{2898\micro mK}{2822K}=1.027\micro m[/tex]
[tex]1\micro m=10^3nm[/tex]
[tex]1.027\micro m=\frac{10^3}{1}\times 1.027=1.027\times 10^3nm[/tex]
Thus wavelength of the spectral maximum in the emission of light by this star is [tex]1027nm[/tex]
A liquid mixture contains water (H2O, MW = 18.0), ethanol (C2H5OH, MW = 46.0) and methanol (CH3OH, MW = 32.0). Using two different analytical techniques to analyze the mixture, it was determined that the water mole fraction was 0.250 while the water mass fraction was 0.134. Determine the mole fraction ethanol (C2H5OH) and the mole fraction methanol (CH3OH) in the solution. Report the values to the correct number of significant figures.
Answer:
Mole fraction of ethanol is 0.363.
Mole fraction of methanol is 0.387.
Explanation:
Mole fraction of water =[tex]\chi_1=0.250[/tex]
Mole fraction of ethanol =[tex]\chi_2[/tex]
Mole fraction of methanol = [tex]\chi_3[/tex]
[tex]\chi_1+\chi_2+\chi_3=1[/tex]
[tex]\chi_2+\chi_3=1-\chi_1=0.750[/tex]
[tex]\chi_2+\chi_3=0.750[/tex]
[tex]\chi_1=\frac{n_1}{n_1+n_2+n_3}[/tex]
[tex]\chi_2=\frac{n_2}{n_1+n_2+n_3}[/tex]
[tex]\chi_3=\frac{n_3}{n_1+n_2+n_3}[/tex]
[tex]n_1+n_2+n_3=1[/tex]
Moles of water = [tex]n_1=0.250 mol[/tex]
Moles of ethanol= [tex]n_2[/tex]
Moles of methanol= [tex]n_3[/tex]
[tex]n_2+n_3=0.750 mol[/tex]
Mass of the mixture = M
Mass of water, [tex]m_1[/tex]
[tex]=n_1\times 18.0 g/mol=0.250 mol\times 18.0 g/mol=4.5 g[/tex]
Fraction of water by mass = 0.134
[tex]\frac{n_1\times 18.0 g/mol}{M}=0.134[/tex]
[tex]M=\frac{0.250 mol\times 18.0 g/mol}{0.134}=33.58 g[/tex]
Mass of ethanol = [tex]m_2[/tex]
Mass of methanol = [tex]m_3[/tex]
[tex]m_1+m_2+m_3=M[/tex]
[tex]4.5 g+m_2+m_3=33.58 g[/tex]
[tex]m_2+m_3=29.08 g[/tex]..[1]
[tex]\frac{m_2}{46.0 g/mol}+\frac{m_3}{32.0 g/mol}=0.750 mol[/tex]
[tex]16m_1+23m_3=552[/tex]..[2]
On solving [1] and [2]:
[tex]m_2 = 16.70, m_3= 12.38 g[/tex]
Mole fraction of ethanol =[tex]chi_2[/tex]
[tex]\chi_2=\frac{n_2}{n_1+n_2+n_3}[/tex]
[tex]=\frac{\frac{16.70 g}{46.0 g/mol}}{1 mol}= 0.363[/tex]
Mole fraction of methanol = [tex]chi_3[/tex]
[tex]\chi_3=\frac{n_3}{n_1+n_2+n_3}[/tex]
[tex]=\frac{\frac{12.38 g}{32.0 g/mol}}{1 mol}= 0.387[/tex]
a reasonable pka for a weak base is:
10.3
0.9
5.8
7.4
13.1
Answer:
0.9
Explanation:
The pka represents the force by which the molecules need to dissociate for the acids ,
Hence , lower the pka stronger will be the acid and that therefore will dissociate completely and vice versa , for a weak acid higher the pka .
And in case of a base , it will be completely reversed , lower pKa , weaker base ,
and higher pKa , stronger base .
From the data of the question ,
0.9 is the lowest value of the pKa , hence , weakest base .
A 200 ml sample of 0.1015 Miric acid is mbred with 2300 ml of water. What is the molar concentration of nitric acid in the final solution 0 406 M 127M 325 x 10 M 5.08 x 10 M 8.12 x 10 M water Backspace lu 'o Pin
Answer: Molar concentration of nitric acid in the final solution is [tex]8.12\times 10^{-3}M[/tex]
Explanation:
According to the dilution law,
[tex]M_1V_1=M_2V_2[/tex]
where,
[tex]M_1[/tex] = molarity of stock [tex]HNO_3[/tex] solution = 0.1015 M
[tex]V_1[/tex] = volume of stock [tex]HNO_3[/tex]solution = 200 ml
[tex]M_2[/tex] = molarity of dilute [tex]HNO_3[/tex] solution = ?
[tex]V_2[/tex] = volume of dilute [tex]HNO_3[/tex] solution = (2300 +200 )ml = 2500 ml
Putting in the values we get:
[tex]0.1015M\times 200=M_2\times 2500[/tex]
[tex]M_2=8.12\times 10^{-3}M[/tex]
Thus the molar concentration of nitric acid in the final solution is [tex]8.12\times 10^{-3}M[/tex]
If 12.5 mL of 0.200 M NaOH was used to reach the equivalence point for in the titration of 25.0 mL of unknown weak acid, HA, the concentration of HA is a. 0.050M b. 0.100M C.0.200M d.0.400M
Answer:
b. 0.100M
Explanation:
The balanced chemical reaction is: NaOH + HA ⇒ H₂O + NaA
The NaOH and HA react in a 1:1 molar ratio, so at the equivalence point, the amount of NaOH added equals the amount of HA that was present in the solution.
The amount of NaOH that was added can be calculated and set equal to the amount of HA that must have been present to react with it.
n = CV = (0.200 mol/L)(12.5 mL) = 2.50 mmol NaOH = 2.50 mmol HA
Thus, there were 2.50 mmol of HA in 25.0 mL. The concentration can be calculated as follow:
C = n/V = (2.50 mmol)/(25.0mL) = 0.100 M
A reaction between substances Y and Z is
representedstochiometrically by
Y2 + Z2 ---> 2YZ
The rate constant obeys the Arrhenius equation. At 435.
K
the rate constant is k = 2.95 e-03 L/mol-s and A = 3.00 e+10
L/mol-s
What is the activation energy (KJ/mol) for
thisreaction?
Answer : The value of activation energy for this reaction is 108.318 kJ/mol
Explanation :
The Arrhenius equation is written as:
[tex]K=A\times e^{\frac{-Ea}{RT}}[/tex]
Taking logarithm on both the sides, we get:
[tex]\ln k=-\frac{Ea}{RT}+\ln A[/tex] ............(1)
where,
k = rate constant = [tex]2.95\times 10^{-3}L/mol.s[/tex]
Ea = activation energy = ?
T = temperature = 435 K
R = gas constant = 8.314 J/K.mole
A = pre-exponential factor = [tex]3.00\times 10^{+10}L/mol.s[/tex]
Now we have to calculate the value of rate constant by putting the given values in equation 1, we get:
[tex]\ln (2.95\times 10^{-3}L/mol.s)=-\frac{Ea}{8.314J/K.mol\times 435K}+\ln (3.00\times 10^{10}L/mol.s)[/tex]
[tex]Ea=108318.365J/mol=108.318kJ/mol[/tex]
Therefore, the value of activation energy for this reaction is 108.318 kJ/mol
What is the Damkohler number? b) What is the significance of a system with a low Damkohler number?
Explanation:
(a) A number which is dimensionless and provides us an estimate of the degree of conversion which can be achieved in CSTR, that is, continuous stirred tank reactor is known as Damkohler number.
This number is denoted as Da.
Mathematically, Da = [tex]\frac{\text{reaction rate}}{\text{convection rate}}[/tex]
Da = [tex]\frac{-rA \times V}{Fa_{o}}[/tex]
Now, for first order system, Da = [tex]\frac{-rA \times V}{Fa_{o}}[/tex]
= [tex]\frac{k \times CA_{o} \times V}{v \times CA_{o}}[/tex] = Tk
where, rA = rate of reaction
V = volume of reactor
[tex]Fa_{o}[/tex] = molar flow rate of component A
k = rate constant
[tex]CA_{o}[/tex] = initial concentration of A
v = volumetric flow rate of A
T = residence time
(b) Since, from a given Damkohler number we can figure out the possible conversion of CSTR, that is, continuous stirred tank reactor.
So, if we have a low Damkohler number then the system will give us a less conversion formula. As the conversion is as follows.
X = [tex]\frac{Da}{Da + 1}[/tex]
Hence, we can conclude that [tex]Da \leq 0.1[/tex] will give less than 10% conversion as calculated by using above formula.
Final answer:
The Damkohler number is a dimensionless number used in chemical engineering to characterize the importance of reaction rates relative to a system's residence time. A system with a low Damkohler number indicates that the chemical reaction is much faster compared to the transport of material. This means that the reaction can be considered essentially instantaneous, and the reactants are fully converted into products within the system before they have a chance to be transported out.
Explanation:
The Damkohler number is a dimensionless number used in chemical engineering to characterize the importance of reaction rates relative to a system's residence time. It is defined as the ratio of the characteristic time for a chemical reaction to occur to the characteristic time for a system to transport material through itself.
A system with a low Damkohler number indicates that the chemical reaction is much faster compared to the transport of material. In practical terms, this means that the reaction can be considered essentially instantaneous, and the reactants are fully converted into products within the system before they have a chance to be transported out.
For example, if we have a packed bed reactor (a reactor where reactants flow through a bed of solid catalyst particles), a low Damkohler number implies that the reaction is so fast that the reactants are fully converted into products even before they can flow through the bed, resulting in high conversion levels.
What is the sum of the numbers of neutrons and electrons in the ion 208 Pb2+?
Answer:
For ²⁰⁸Pb²⁺ cation, the sum of the number of neutrons and electrons = 206
Explanation:
Lead, chemical symbol Pb, is a chemical element which belongs to the group 14 of the periodic table. The atomic number of lead is 82 and it is a member of the p-block.
The isotope of lead with the mass number 208, has 126 neutrons.
Since, atomic number = number of protons = number of electrons for neutral atom
Therefore, for ²⁰⁸Pb: number of electrons= 82
So, for ²⁰⁸Pb²⁺ cation: number of electrons= 82 - 2 = 80
Therefore, for ²⁰⁸Pb²⁺ cation, the sum of the number of neutrons and electrons = number of electrons + number of neutrons = 80 electrons + 126 neutrons = 206.