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The **Clausius-Clapeyron Equation** establishes a quantitative relationship between **vapor pressure** and **temperature**.

Concept #1: Understanding the Clasius-Clapeyron Equation

**Transcript**

We're going to say by using the Clasius-Clapeyron equation, a quantitative relationship between vapor pressure and temperature can be established. The question here is ln of P2 over P1 equals negative delta H of vaporization. Remember, delta H is enthalpy. Enthalpy of vaporization over R times 1 over T2 minus 1 over T1. We're going to say here that R, since we’re dealing with enthalpy is 8.314 joules over more times K.

Vapor Pressure looks at the equilibrium established between vaporization and condensation. By using the Clasius-Clapeyron equation, the enthalpy of vaporization can be determined.

Example #1: The heat of vaporization (Δ**H _{vap}**) of water is 40.3 kJ/mol at its normal boiling point at 100

0 of 2 completed

Concept #1: Understanding the Clasius-Clapeyron Equation

Example #1: The heat of vaporization (Hvap) of water is 40.3...

Which of the following is NOT true about the Clausius-Clapeyron equation?
A) It is a way to measure the heat of vaporization in the laboratory
B) The equation describes an exponential relationship
C) B is a constant based on a particular gas
D) Its graph represents the natural log of the vapor pressure by the inverse of temperature
E) The graphed data is linear

How much energy is required to vaporize 98.6 g of ethanol (C2H5OH) at its boiling point, if its ΔHvap is 40.5 kJ/mol?
A) 86.7 kJ
B) 11.5 kJ
C) 18.9 kJ
D) 52.8 kJ
E) 39.9 kJ

Which compound has the lowest boiling point?

Mercury is a neurotoxic metal with a reasonable high vapor pressure, at least for a metal. The vapor pressure at 25°C is 0.0017 mmHg. But what about the vapor pressure of mercury in a factory where the temperature is 32°C? Will the vapor pressure of mercury be higher or lower in the factory? The enthalpy of vaporization of mercury is 59.11 kJ/mol.

Calculate the vapor pressure (mmHg) of potassium at 150°C. The normal boiling point of potassium is 775°C. The heat of vaporization is 81.3 kJ/mol
a) 7.82 x 10 -4 mmHg
b) 0.451 mmHg
c) 237 mmHg
d) 2.81 x 10 -2 mmHg
e) 624 mmHg

How many of the following would be associated with an increase in the rate of vaporization?
• An increase in temperature
• An increase in the strength of intermolecular forces
• An increase in the amount of surface area
• An increase in vapor pressure
A. none B. one C. two D. three E. four

At room temperature, a sample of some compound has a vapor pressure of 454 torr. At what temperature will the solution have a vapor pressure of 900 Torr? ∆Hvap of compound is 25.8 kJ/mol.
A. 319 K
B. 258 K
C. 298 K
D. 416 K

The vapor pressure of benzene, C6H6, is 40.1 mmHg at 1.6 °C. What is its vapor pressure at 60.6 °C? The molar heat of vaporization of benzene is 31.0 kJ/mol.

It was determined that the normal boiling point of a compound was 183.5°C. When the boiling point was measured at 300 mmHg, it was a 136.8°C. What is the heat of vaporization (kJ/mol) of this compound? a. 31.0 KJ/molb. 56.7 KJ/molc. 93.9 KJ/mold. 145 KJ/mole. 188 KJ/mol

The normal boiling point of bromine is 58.8°C. Given that the vapor pressure of bromine is 75.0 torr at 2.5°C, calculate the molar enthalpy of vaporization of bromine.a) 3.76 kJ/molb) 2.90 kJ/molc) 29.7 kJ/mold) 3.57 kJ/mole) 31.3 kJ/mol

For the decomposition of ammonia to nitrogen and hydrogen, the equilibrium constant is 1.47 x 10-6 at 298 K. Calculate the temperature at which K = 0.01. For reaction, ΔH° = 92.38 kJ • mol-1.1. 390 K2. 59 K3. 117 K4. 241 K5. 468 K

What is the vapor pressure (in atm) of a liquid at its normal boiling point? ___________________

Which solids will melt under applied pressure? Check all that apply.

Four alcohols have the formula C4H9OH:1-butanol, 2-butanol (or sec-butanol), isobutanol (or 2-methyl-1-propanol), and tert-butanol (or 2-methy;-2-propanol).They are examples of isomers, or compounds that have the same molecular formula but different molecular structures. The below table gives data on the isomers:Using the Clausius-Clapeyron equation, rank the isomers of butanol in order of decreasing vapor pressure at 25 °C. Does the ranking agree with any conventional wisdom based on the ΔvapH Values or the normal boiling points?

Ethanol has a heat of vaporization of 38.56 kJ/mol and a normal boiling point of 78.4 °C. What is the vapor pressure of ethanol at 14°C?

The vapor pressure of ammonia at several different temperatures is shown below.a. Use the date to determine the heat of vaporization of ammoniab. Determine the normal boiling point of ammonia.

A certain substance has a heat of vaporization of 47.70 kJ/mol. At what kelvin temperature will the vapor pressure be 3.50 times higher than it was at 293K?

Ethanol has a heat of vaporization of 38.56 kJ/mol and a normal boiling point of 78.4 C.What is the vapor pressure of ethanol at 15°C?

The following equation represents the decomposition of a generic diatomic element in its standard state.1/2 X2(g) → X(g)Assume that the standard molar Gibbs energy of formation of X(g) is 4.76 kJ•mol-1 at 2000. K and - 65.63 kJ•mol-1 at 3000. K. Determine the value of K (the thermodynamic equilibrium constant) at each temperature.K at 2000. K = _____K at 3000. K = _____Assuming that delta H°rxn, is independent of temperature, determine the value of Δ H°rxn from these data.ΔH°rxn = ______ kJ mol-1

A certain liquid has a vapor pressure of 92.0 Torr at 23.0°C and 332.0 Torr at 45.0° C. Calculate the value of ΔH°vap for this liquid in kJ/mol.Calculate the normal boiling point of this liquid in °C.

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