1. Separation of amino acids by ion-exchange Chromatography. Mixtures of amino acids can be analyzed by first separating the mixture into its components through ion-exchange chromatography. Amino acids placed on a cation-exchange resin containing sulfate (-SO3-) groups flow down the column at different rates because of two factors that influence their movement (1) ionic attraction between the sulfonate residues on the column and positively charged functional groups on the amino acids, and (2) hydrophobic interactions between amino acid side chains and the strongly hydrophobic backbone of the polystyrene resin. For each pair of amino acids listed, determine which will be eluted first from the cation-exchange column by a ph 7.0 buffer.

a.) Asp and Lys

b.) Arg and Met

c.) Glu and Val

d.) Gly and Val

e.) Ser and Ala

The statement "Although sulfuric acid is a strong electrolyte, an aqueous solution of H₂SO₄ contains more HSO₄⁻ ions than SO₄²⁻ ions is True. This is best explained by the fact that H₂SO₄ is a diprotic acid where only the first hydrogen completely ionizes.

Why?

H₂SO₄ is a diprotic acid. That means that it has two hydrogen ions to give to the solution. The two dissociation reactions are shown below:

H₂SO₄ + H₂O → HSO₄⁻ + H₃O⁺

HSO₄⁻ + H₂O ⇄ SO₄²⁻ + H₃O⁺

As the arrows show, the first dissociation is complete, meaning that all the sulfuric acid that is present initially is dissociated into HSO₄⁻ and H₃O⁺. However, the second dissociation is incomplete, and it's actually an equilibrium with an acid constant  (Ka)of 1.2×10⁻².

That means that if the initial concentration of H₂SO₄ was 1M, the concentration of HSO₄⁻ is going to be 1M as well, but the concentration of SO₄²⁻ is going to be much less than 1M, according to the dissociation constant.

Have a nice day!

Answer:

There are 1.05  x 10²⁴ molecules in 48.6 g N₂

Explanation:

1 mol of N₂ has a mass of (14 g * 2) 28 g.

Then, 48.6 g of N₂ will be equal to (48.6 g *(1 mol/ 28 g)) 1.74 mol.

Since there are 6.022 x 10²³ molecules in 1 mol N₂, there will be

(1.74 mol *( 6.022 x 10²³ / 1 mol)) 1.05  x 10²⁴ molecules in 1.74 mol N₂ (or 48. 6 g N₂).

Answer:

The enzyme unit

Explanation:

Enzymes are catalyst, meaning that they make chemical reactions faster.

For measuring the catalytic activity of an enzyme there are two common units The enzyme unit and The Katal.

The first one is defined as the amount of enzyme that catalyzes the reaction of 1 micromole of substrate in a minute, on the other hand the katal is give for 1 mole per second. Since 1 mol is a huge amount in terms of enzymes, it is usually use the prefix nano- (10^-9).

1 U = 16.67 nKat if you need a conversion factor.

Hope it helps!

Answer: The mass of zinc oxalate, the chemist has added is [tex]7.6\times 10^5mg[/tex]

Explanation:

To calculate the mass of solute, we use the equation used to calculate the molarity of solution:

[tex]\text{Molarity of the solution}=\frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution (in L)}}[/tex]

We are given:

Molarity of solution = [tex]1.08\times 10M=10.8M[/tex]

Molar mass of zinc oxalate = 155.4 g

/mol

Volume of solution = 0.45 L

Putting values in above equation, we get:

[tex]10.8M=\frac{\text{Mass of zinc oxalate}}{155.4g/mol\times 0.45L}\\\\\text{Mass of zinc oxalate}=(10.8mol/L\times 155.4g/mol\times 0.45L)=7.6\times 10^2g[/tex]

To convert the calculated mass into milligrams, we use the conversion factor:

1 g = 1000 mg

So, [tex]7.6\times 10^2g\times \frac{1000mg}{1g}=7.6\times 10^5mg[/tex]

Hence, the mass of zinc oxalate, the chemist has added is [tex]7.6\times 10^5mg[/tex]

3NF3 + 5H2O → HNO3 + 2NO + 9HF

Nitrogen fluoride reacts with water to produce nitric acid, nitric oxide, and hydrogen fluoride. The reaction slowly takes place in a boiling solution.

CH2CH2 + H2O → CH3CH2OH

Ethylene is a hydrocarbon with water that creates ethanol and ethanol is an alcohol

Answer: The correct answer is Option a.

Explanation:

To calculate the molarity of solution, we use the equation:

[tex]\text{Molarity of the solution}=\frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution (in L)}}[/tex]

We are given:

Mass of solute (carbon dioxide) = 44 g

Molar mass of carbon dioxide = 44 g/mol

Volume of solution = 0.5 L

Putting values in above equation, we get:

[tex]\text{Molarity of solution}=\frac{44g}{44g/mol\times 0.5L}\\\\\text{Molarity of solution}=2mol/L[/tex]

Hence, the correct answer is Option a.

Answer: The mass of oxygen gas required is 36.7 grams.

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 hexane = 10.4 g

Molar mass of hexane = 86.18 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of hexane}=\frac{10.4g}{86.18g/mol}=0.12mol[/tex]

The chemical equation for the combustion of hexane follows:

[tex]2C_6H_{14}+19O_2\rightarrow 12CO_2+14H_2O[/tex]

By stoichiometry of the reaction:

2 moles of hexane reacts with 19 moles of oxygen gas

So, 0.12 moles of hexane will react with = [tex]\frac{19}{2}\times 0.12=1.14mol[/tex] of oxygen gas.

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

Molar mass of oxygen gas = 32 g/mol

Moles of oxygen gas = 1.14 moles

Putting values in equation 1, we get:

[tex]1.14mol=\frac{\text{Mass of oxygen gas}}{32g/mol}\\\\\text{Mass of oxygen gas}=36.7g[/tex]

Hence, the mass of oxygen gas required is 36.7 grams.

Answer:

Explanation:

Kinetic energy is the energy due to the motion of a body. Potential energy is the energy at rest.

Kinetic energy is dependent on the mass and velocity at which a body is moving. Potential energy is a function of altitude and acceleration due to gravity on a body.

   K.E = [tex]\frac{1}{2} mv^{2}[/tex]

  where m is the mass of the plane and v is the velocity at which the plane moves.

  P.E= mgh

   m is the mass of the plane, g is the acceleration due to gravity acting on it and h is the height or altitude of the plane.

A moving airplane shuffles between both kinetic and potential energy. When the altitude of plane changes there is a noticeable change in its potential energy. A plane has to change its velocity from time to time in order to over come drag and gravity, this incurs kinetic energy on the plane.

The mechanical energy in plane thrusters are converted to do effect kinetic and potential energy.

Final answer:

The mass percent of ethanol in wine is approximately 10.38%, and the molality of ethanol in wine is approximately 2.51 mol/kg. These values are calculated from the given volume percent and the density of ethanol by first determining the mass of ethanol and then the number of moles of ethanol.

Explanation:

Calculating Mass Percent and Molality of Ethanol in Wine

We are given that wine contains 12.8% ethanol by volume, and the density of ethanol is 0.789 g/cm3. To find the mass percent and molality of ethanol in wine, we proceed with the following steps:

Through these calculations, we have determined both the mass percent and molality of ethanol in the wine sample.

Answer:

Carbohydrates are the biological molecules having a general emperical formula [tex]C_{m} (H_{2} O)_{n}[/tex].  

There are various important biological functions of carbohydrates. Carbohydrates serve as structural components, component of coenzymes, and backbone of RNA. Carbohydrates provide and store energy, and also plays important role in blood clotting, development, immune system, and preventing pathogenesis.

Answer:

Environment refers to everything that surrounds an individual and interacts between them. The factors that control the environment can be biotic and abiotic.

Humans have greatly affected the environment. Some of the ways in which the environment is affected by humans are as follows-

(1) Humans have constructed industries and factories that have released a huge amount of toxic gases into the atmosphere.

(2) These harmful gases have increased the earth's global temperature. As a result of which the global warming effect has increased.

(3) The waste materials eliminated from these industries mix with the rivers and streams and pollute the water. It degrades water quality.

(4) The fossil fuels are exhausted at a very high rate.

(5) The spilling of the oils in the oceans has affected the marine species drastically.

(6) Due to the extensive mining at different places, soil fertility has decreased considerably.

(7) Cutting down trees for settlement purposes and other infrastructures.

The environmental impact of human activities can be measured using the Ecological Footprint model, which calculates the resources consumed and waste generated by our actions. The Precautionary Principle is critical when understanding environmental effects is limited, advocating for caution. Reducing our carbon footprint through simple tasks like walking instead of driving can greatly contribute to environmental health.

To determine the environmental impact of human activities, one can use the Ecological Footprint model developed by William Rees and Mathis Wackernagel. This model measures the amount of biologically productive land and water area required to produce the resources a person, population, or activity consumes and to absorb the waste they generate, given prevailing technology and resource management practices.

Appraising the ways in which human intervention has altered the environment often leads to a blurred line between 'natural' and human-influenced ecosystems. One principle to consider when the effects of an activity on the environment are not well understood is the Precautionary Principle. This suggests that in the absence of clear data, we must assume that harm to the environment could occur and therefore proceed cautiously with any such activities.

Individual choices, like walking instead of driving, can lead to reducing one's overall carbon footprint. This collective effort is critical as it can mitigate some of the negative impacts humans have on the environment, including air pollution, which is significantly attributed to human activity such as transport and industrial processes. Moreover, adjusting consumption patterns and holding corporations accountable for environmental degradation are also key steps towards sustainability.

Answer:

a) The concentration in ppm (mg/L) is 5.3 downstream the release point.  

b) Per day pass 137.6 pounds of pollutant.  

Explanation:

The first step is to convert Million Gallons per Day (MGD) to Liters per day (L/d). In that sense, it is possible to calculate with data given previously in the problem.  

Million Gallons per day [tex]1 MGD = 3785411.8 litre/day = 3785411.8 L/d[/tex]

[tex]F_1 = 5 MGD (\frac{3785411.8 L/d}{1MGD} ) = 18927059 L/d\\F_2 =10 MGD (\frac{3785411.8 L/d}{1MGD} )= 37854118 L/d [/tex]

We have one flow of wastewater released into a stream.  

First flow is F1 =5 MGD with a concentration of C1 =10.0 mg/L.

Second flow is F2 =10 MGD with a concentration of C2 =3.0 mg/L.  

After both of them are mixed, the final concentration will be between 3.0 and 10.0 mg/L. To calculate the final concentration, we can calculate the mass of pollutant in total, adding first and Second flow pollutant, and dividing in total flow. Total flow is the sum of first and second flow. It is shown in the following expression:  

[tex]C_f = \frac{F1*C1 +F2*C2}{F1 +F2}[/tex]

Replacing every value in L/d and mg/L

[tex]C_f = \frac{18927059 L/d*10.0 mg/L +37854118 L/d*10.0 mg/L}{18927059 L/d +37854118 L/d}\\C_f = \frac{302832944 mg/d}{56781177 L/d} \\C_f = 5.3 mg/L[/tex]

a) So, the concentration just downstream of the release point will be 5.3 mg/L it means 5.3 ppm.

Finally, we have to calculate the pounds of substance per day (Mp).  

We have the total flow F3 = F1 + F2 and the final concentration [tex]C_f[/tex]. It is required to calculate per day, let's take a time of t = 1 day.  

[tex]F3 = F2 +F1 = 56781177 L/d \\M_p = F3 * t * C_f\\M_p = 56781177 \frac{L}{d} * 1 d * 5.3 \frac{mg}{L}\\M_p = 302832944 mg[/tex]

After that, mg are converted to pounds.  

[tex]M_p = 302832944 mg (\frac{1g}{1000 mg} ) (\frac{1Kg}{1000 g} ) (\frac{2.2 lb}{1 Kg} )\\M_p = 137.6 lb[/tex]

b) A total of 137.6 pounds pass a given spot downstream per day.

To find the concentration in ppm just downstream, we calculate the mass of the pollutant using the flow rate and concentration. The concentration in ppm just downstream is 50 ppm. To find the number of pounds of substance per day passing a given spot downstream, we convert the mass from grams to pounds.

In order to find the concentration in ppm just downstream, we need to calculate the mass of pollutant that is being released into the stream. We can use the following formula:

Mass = Flow rate x Concentration

Using the given flow rates and concentrations:

Upstream Mass = 10 MGD x 3.0 mg/L = 30 mg/L

Downstream Mass = 5 MGD x 10.0 mg/L = 50 mg/L

So the concentration in ppm just downstream is:

50 mg/L x (1 ppm/1 mg/L) = 50 ppm

To find the number of pounds of substance per day passing a given spot downstream, we will need to calculate the mass in pounds. We can use the following conversions:

1 lbm = 2.2 kg

1 kg = 1000 g

1 g = 1000 mg

Using the given flow rate and concentration:

Downstream Mass (in g/day) = 5 MGD x 10.0 mg/L = 50,000 g/day

Downstream Mass (in kg/day) = 50,000 g/day x (1 kg/1000 g) = 50 kg/day

Downstream Mass (in lbm/day) = 50 kg/day x (1 lbm/2.2 kg) = 22.7 lbm/day

So the number of pounds of substance per day passing a given spot downstream is approximately 22.7 pounds.

Answer:

The rate constant [tex]k_{2}[/tex] at 84.8°C is [tex]k_{2}=6.423sec^{-1}[/tex]

Explanation:

Taking the Arrhenius equation we have:

[tex]ln\frac{k_{2}}{k_{1}}=\frac{E_{a}}{R}(\frac{1}{T_{1}}-\frac{1}{T_{2}})[/tex]

Where [tex]k_{2}[/tex] is the rate constant at a temperature 2, [tex]k_{1}[/tex] is the rate constant at a temperature 1; [tex]T_{1}[/tex] is the temperature 1, [tex]T_{2}[/tex] is the temperature 2, R is the gas constant and [tex]E_{a}[/tex] is the activation energy.

Now, we need to solve the equation for [tex]k_{2}[/tex], so we have:

[tex]ln\frac{k_{2}}{k_{1}}=\frac{E_{a}}{R}(\frac{1}{T_{1}}-\frac{1}{T_{2}})[/tex]

[tex]ln({k_{2})-ln(k_{1})=\frac{E_{a}}{R}(\frac{1}{T_{1}}-\frac{1}{T_{2}})[/tex]

[tex]ln(k_{2})=E_{a}(\frac{1}{T_{1}}-\frac{1}{T_{2}})+ln(k_{1})[/tex]

Then we need to make sure that we are working with the same units, so:

[tex]R=8.314\frac{J}{mol.K}[/tex]

[tex]T_{1}=16.6^{o}C+273.15=289.75K[/tex]

[tex]T_{2}=84.4^{o}C+273.15=357.95K[/tex]

And now we can replace the values into the equation:

[tex]ln(k_{2})=\frac{22000\frac{J}{mol}}{8.314\frac{J}{mol.K}}(\frac{1}{289.75K}-\frac{1}{357.95K})+ln(1.868sec^{-1})[/tex]

[tex]ln(k_{2})=2646.139K(0.003451K^{-1}-0.002794K^{-1})+0.6249[/tex]

[tex]ln(k_{2})=2.363sec^{-1}[/tex]

To solve the ln we have to apply e in both sides of the equation, so we have:

[tex]e^{ln(k_{2})}=e^{2.363}sec^{-1}[/tex]

[tex]k_{2}=6.423sec^{-1}[/tex]

Answer:

10.37 s-1

Explanation:

From

k= A e-^Ea/RT

Given

Ea=22KJmol-1

T=16.6+273= 289.6K

k= 1.868 sec-1

R= 8.314JK-1mol-1

A???

Hence

A= k/e^-Ea/RT

A= 1.868/e-(22000/8.314×289.6)

A= 1.7 ×10^4

Substitute into to find k at 84.8°C

k= 1.7×10^4× e-(22000/8.314×357.8)

k=10.37 s-1

Answer: A hydrogen bonding is interaction between lone pair and hydrogen atom. An Ion-Dipole interaction is the interaction between an ion formed and a dipole. Dipole forms because of the electronegativity difference between two atom participating in the bond formation, and an ion is formed when an atom gains or lose electron. This ion-dipole interaction is strongest interaction.

Therefore, The right choice is (B)

Answer: The mass of oxygen reacted is [tex]1.60\times 10^{3}g[/tex]

Explanation:

We are given:

Moles of propane = 9.98 mol  

For the given chemical equation:

[tex]C_3H_8(g)+5O2(g)\rightarrow 3CO_2(g)+4H_2O(g)[/tex]

By Stoichiometry of the reaction:

1 mole of propane reacts with 5 moles of oxygen.

So, 9.98 moles of propane will react with = [tex]\frac{5}{1}\times 9.98=49.9mol[/tex] of oxygen.

To calculate the mass of carbon dioxide, we use the equation:

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

Moles of oxygen = 49.9 moles  

Molar mass of oxygen gas = 32 g/mol

Putting values in above equation:

[tex]49.9mol=\frac{\text{Mass of oxygen}}{32g/mol}\\\\\text{Mass of oxygen}=(49.9mol\times 32g/mol)=1596.8g=1.60\times 10^{3}g[/tex]

Hence, the mass of oxygen reacted is [tex]1.60\times 10^{3}g[/tex]

Answer:

2.4E-4

Explanation:

Hello,

By applying the following mass-mole relationship, the concentration could be computed as follows (assuming molarity as long as it isn't specified), since in the silver carbonate two silver molecules are present:

[tex][Ag]=1.2x10^{-4}\frac{molAg_2CO_3}{L} *\frac{2mol Ag}{1 mol Ag_2CO_3}=2.4x10^{-4}\frac{mol Ag}{L}[/tex]

Best regards.

Answer:

In 3.5 x 10^(15) J of energy there are 9*10^(33) photons.

Explanation:

To solve this problem, we need two equations.

The equation of light velocity, wich is a relation between wavelenght and frecuency.

                                                      c=λν            (1)

where:

The Photoelectric Effect equation, that refers to the energy absorbed or emanate by ONE photon.

                                                             E = hν            (2)

where:

The first we do is to calculate the frecuency of the flash using equation (1). The wavelenght of the flash is 510 nm = 510 * 10^(-9) m

c=λν........................ ν= c/λ = 3 × 10^8 [m/s]/  510 * 10^(-9) m  = 5,88 * 10^(14) 1/s

Note: small wavelenghts always have big frequencies

Now, we use the photoelectric effect equation to calculate the amount of energy that ONE  photon can abosrb.

 E = hν  ..................... E = 6,626*10^{-34} [J.s] * 5,88 * 10^(14) 1/s =3,9 * 10^(-19) J

To know the number of photons, we just have to divide the TOTAL amount of energy between the energy of ONE photon. So:

# photons = 3.5 x 10^(15) J / 3,9 * 10^(-19) J = 9*10^(33) photons.

Answer: Wavelength of ultraviolet light is 54 nm.

Explanation:

Electromagnetic wave is defined as the wave which is associated with both electrical and magnetic component associated with them. They can travel in vacuum as well and travel with the speed of light.

The relationship between wavelength and frequency of the wave follows the equation:

[tex]\nu=\frac{c}{\lambda}[/tex]

where,

[tex]\nu[/tex] = frequency of the wave  =[tex]5.5\times 10^{15}Hz[/tex]

c = speed of light  =[tex]3\times 10^8ms^{-1}[/tex]

[tex]\lambda [/tex] = wavelength of the wave  

Putting in the values we get:

[tex]5.5\times 10^{15}s^{-1}=\frac{3\times 10^8ms^{-1}}{\lambda}[/tex]

[tex]\lambda=0.54\times 10^{-7}m[/tex]

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

[tex]\lambda=54nm[/tex]

Thus wavelength of ultraviolet light is 54 nm.

Answer : The energy required is, 574.2055 KJ

Solution :

The conversions involved in this process are :

[tex](1):H_2O(s)(-10^oC)\rightarrow H_2O(s)(0^oC)\\\\(2):H_2O(s)(0^oC)\rightarrow H_2O(l)(0^oC)\\\\(3):H_2O(l)(0^oC)\rightarrow H_2O(l)(95^oC)[/tex]

Now we have to calculate the enthalpy change or energy.

[tex]\Delta H=[m\times c_{p,s}\times (T_{final}-T_{initial})]+n\times \Delta H_{fusion}+[m\times c_{p,l}\times (T_{final}-T_{initial})][/tex]

where,

[tex]\Delta H[/tex] = energy required = ?

m = mass of ice = 1 kg  = 1000 g

[tex]c_{p,s}[/tex] = specific heat of solid water = [tex]2.09J/g^oC[/tex]

[tex]c_{p,l}[/tex] = specific heat of liquid water = [tex]4.18J/g^oC[/tex]

n = number of moles of ice = [tex]\frac{\text{Mass of ice}}{\text{Molar mass of ice}}=\frac{1000g}{18g/mole}=55.55mole[/tex]

[tex]\Delta H_{fusion}[/tex] = enthalpy change for fusion = 6.01 KJ/mole = 6010 J/mole

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

[tex]\Delta H=[1000g\times 4.18J/gK\times (0-(-10))^oC]+55.55mole\times 6010J/mole+[1000g\times 2.09J/gK\times (95-0)^oC][/tex]

[tex]\Delta H=574205.5J=574.2055kJ[/tex]     (1 KJ = 1000 J)

Therefore, the energy required is, 574.2055 KJ

Answer:

Components that are mixed can be in different states of matter.

Explanation:

A mixture is often described as an impure substance. It has the following properties:

There are two types of mixture; homogenous mixtures have their constituents existing in one phase.

Heterogenous mixtures have constituents in different phases. The phases are the different states of matter.

One of the properties of a mixture is that; Components that are mixed can be in different states of matter.

Definition;

A mixture put simply can be defined as an impure substance which is made up of different constituents with each constituent possessing its own unique properties.

Additionally, mixtures are subdivided into homogeneous and heterogeneous mixtures;

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Answer:

Ba(OH)2 (aq) + H2SO4(aq) → BaSO4(s) + 2 H2O(l)

That's the right one.

Explanation:

You should see that this equation is balanced, not as

Ba(OH)2 (aq) + H2SO4(aq) → BaSO4(s) + H2O(l)

(on reactive we have 4 H, on products, we have only 2)

Ba(OH)2 (aq) + H2SO4(aq) → H2Ba(s) + SO4(OH)2(l)

(this is impossible, it's a nonsense)

BaSO4(s) + 2 H2O(l) → Ba(OH)2 (aq) + H2SO4(aq)

(it is the same with the right one but is the other way around. The statement says, reaction of Ba(OH)2 with H2SO4, not BaSO4 with water. Also, it is not a chemical balance.

Answer:

Time = 3.27s

Explanation:

Time = Distance / Speed

Time = 42.2 / 12.9 = 3.2713

When you multiply the number of significant figures in the result is the same as the number with the least significant figures.

In this case 42.2 has 3 significant figures and 12.9 also has 3 significant figures, therefore the answer must have 3 significant figures too.

Time = 3.27 s

The approximate density of a high-leaded brass composed of 64.5% Cu, 33.5% Zn and 2.0% Pb can be calculated using the rule of mixtures; Density = (wt% Cu/100)*ρCu + (wt% Zn/100)*ρZn + (wt% Pb/100)*ρPb.

This question is about the calculation of the approximate density of a high-leaded brass that has a composition of 64.5 wt% Cu, 33.5 wt% Zn and 2.0 wt% Pb with known individual densities. The density of a mixture can be calculated using the rule of mixtures. The rule of mixtures states that the density of a mixture is equal to the mass fractions of each component times their respective densities. The calculation is as follows:

Density of Brass = (wt% Cu/100)*ρCu + (wt% Zn/100)*ρZn + (wt% Pb/100)*ρPb

By substituting the values, we get:

Density of Brass = (64.5/100)*8.94 g/cm³ + (33.5/100)*7.13 g/cm³ + (2.0/100)*11.35 g/cm³

Hence, the approximate density of the high-leaded brass can be determined by calculating the above equation.

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The enthalpy of vaporization for pyridine can be calculated using the Clausius-Clapeyron equation. Given that the vapor pressure of pyridine is 50.0 kPa at 365.7 K, and its boiling point is 388.4K, we can substitute these values into the equation to find the enthalpy of vaporization.

The question is asking for the enthalpy of vaporization of pyridine. We first need to apply the Clausius-Clapeyron equation which is

ln(P2/P1) = -ΔHvap/R *(1/T1 - 1/T2), where P2 is the vapor pressure at the boiling point (1.00 atm or 101.3 kPa), P1 is the given vapor pressure (50.0 kPa), ΔHvap is the enthalpy of vaporization which we want to find, R is the gas constant (8.314 J/K.mol), T1 is 365.7 K, and T2 is the boiling point (388.4 K). By rearranging and substituting the values into the equation, one can solve for ΔHvap to find its value. Remember always to convert the pressure units into the same, in this case we used kilopascal.

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Answer:

Take 46.9 ml of the 12 M solution using a graduated cylinder and pour the liquid in a 250-ml volumetric flask. Add water until the mark.

Explanation:

To prepare this solution, you have to take a volume of the 12 M HCl solution and add water to 250 ml. What volume should you take?

The number of moles of HCl present in the volume you take from the concentrated solution will be the same as the number of moles in the final solution since you are only adding water. Then:

number of moles of HCl in the taken volume = number of moles in the final solution.

number of moles of HCl = concentration (in molarity) * volume

Then:

Ci * Vi = Cf * Vf

Where

Ci = the concentration of the solution from which you take the volume to prepare the more diluted solution.

Vi = the volume of the concentrated solution you have to take.

Cf = Concentration of the final solution

Vf = volume of the final solution

Replacing with the data:

12.0 M * Vi = 250.00 ml * 2.25M

Vi = 46.9 ml

Answer:

(4.29×10¹⁵)⋅(1.96×10⁻⁴) = 8.40 × 10¹¹, has three significant digits.

Explanation:

To solve: (4.29×10¹⁵)⋅(1.96×10⁻⁴)

According to the product rule of exponents, when exponents having the same base are multiplied, the base is kept the same and the powers are added.

Therefore,

(4.29×10¹⁵)⋅(1.96×10⁻⁴) = (4.29 × 1.96) · 10⁽¹⁵⁻⁴⁾ = 8.40 × 10¹¹

The number, 8.40 × 10¹¹ has three significant digits.

To calculate the product of (4.29×1015) and (1.96×10−4), multiply the significant figures to get 8.4084, then add the exponents to get 1011, and combine them to express the product in scientific notation as 8.41×1011, rounded to three digits.

Explanation:

To compute the product of (4.29×1015) and (1.96×10−4), you multiply the significant figures and then add the exponents of 10. First, multiply the significant figures:

4.29 × 1.96 = 8.4084.

Next, add the exponents:

1015 × 10−4 = 1015−4 = 1011.

Combine the significant figure product with the exponent sum to express the answer in scientific notation:

8.4084 × 1011 → 8.41×1011 (rounded to three digits).

Answer:

C : CH₃OH

Explanation:

According to the concept of Bronsted - Lowry -

An acid is a substance , that can give a proton .

A base is a substance , that can take a proton .

According to the reaction given in the question ,

CH₃OH   +   HI   -->    CH₃OH₂⁺   +  I⁻

From , the above reaction ,

It is visible that , the reactant CH₃OH accepts a proton and forms CH₃OH₂⁺  , thereby acting as a base ,

And ,  HI act as an acid , as is losses a proton and becomes  I⁻ .

Hence ,

In the above reaction ,  CH₃OH act as a base .

Answer: The formula mass of caffeine is 97 amu and molar mass of caffeine is 194 g/mol

Explanation:

Formula mass is defined as the sum of the mass of all the atoms each multiplied its atomic masses that are present in the empirical formula of a compound. It is expressed in amu.

Molar mass is defined as the sum of the mass of all the atoms each multiplied its atomic masses that are present in the molecular formula of a compound. It is expressed in g/mol.

Empirical formula is defined as the formula in which atoms in a compound are present in simplest whole number ratios.

The molecular formula of caffeine is [tex]C_8H_{10}N_4O_2[/tex]

Dividing each number of atoms by '2', we will get the empirical formula of caffeine. The empirical formula of caffeine is [tex]C_4H_5N_2O[/tex]

We know that:

Atomic mass of carbon = 12 amu

Atomic mass of hydrogen = 1 amu

Atomic mass of nitrogen = 14 amu

Atomic mass of oxygen = 16 amu

Formula mass of caffeine = [tex](4\times 12)+(5\times 1)+(2\times 14)+(1\times 16)]=97amu[/tex]

Molar mass of caffeine = [tex](8\times 12)+(10\times 1)+(4\times 14)+(2\times 16)]=194g/mol[/tex]

Hence, the formula mass of caffeine is 97 amu and molar mass of caffeine is 194 g/mol

Answer: Option (a) is the correct answer.

Explanation:

A chemical change is defined as the change which brings difference in the composition of reacting species.

Therefore, during a chemical change there will always be formation of new compounds.

For example, [tex]2Na + Cl_{2} \rightarrow 2NaCl[/tex] is a chemical change as new substance formed is NaCl.

So basically, a chemical reaction equation or system tells the overall change occuring in the system.

Mechanism of a reaction can only be determined theoretically and not just by examining a chemical system.

Intermediates cannot be isolated as they are very reactive species. Hence, they cannot be determined by examining a chemical system.

Activated complex are the intermediate substances which are formed during the reaction and they cannot be isolated. Hence, they cannot be determined by examining a chemical system.

Thus, we can conclude that examining a chemical system before and after a reaction reveals the net chemical change.

The substances Ar, Cl2, CH4, and CH3COOH can be ranked in increasing order of strength of intermolecular attractions as CH4 < Ar < Cl2 < CH3COOH.

The intermolecular forces in the given substances can be ranked from weakest to strongest as follows: