Question 1

Which of the following substances has the highest boiling point according to the vapor pressure curves shown in the provided graph?

Accepted Answer

Ethylene glycol

Question 2

A liquid boils when its vapor pressure equals atmospheric pressure. If the atmospheric pressure is decreased, what happens to the boiling point of water?

Accepted Answer

It decreases

Question 3

Given the following standard enthalpies of formation: $\Delta H_f^\circ$(CO$_2$(g)) = -393.5$ kJ/mol, $\Delta H_f^\circ$(H$_2$O(l)) = -285.8$ kJ/mol, $\Delta H_f^\circ$(C$_6$H_{12}$O_6$(s)) = -1273.3$ kJ/mol$, calculate the enthalpy change for the combustion of glucose: $C_6H_{12}O_6(s) + 6O_2(g) \rightarrow 6CO_2(g) + 6H_2O(l)$.

Accepted Answer

$\Delta H = -2870$ kJ

Question 4

Which intermolecular force is primarily responsible for the high boiling point of water compared to ethanol and diethyl ether?

Accepted Answer

Hydrogen bonding

Question 5

If a sample of ethanol is heated from 20°C to its boiling point at 78°C, which of the following best describes the change in vapor pressure?

Accepted Answer

Vapor pressure increases

Question 6

A solution is prepared by mixing ethylene glycol and water. Compared to pure water, what effect does the presence of ethylene glycol have on the vapor pressure of the solution?

Accepted Answer

It decreases the vapor pressure

Question 7

Which of the following statements about vapor pressure is correct?

Accepted Answer

Vapor pressure increases with temperature

Question 8

Using the Clausius-Clapeyron equation $\ln\left(\frac{P_2}{P_1}\right) = -\frac{\Delta H_{vap}}{R}\left(\frac{1}{T_2} - \frac{1}{T_1}\right)$, which variable represents the enthalpy of vaporization?

Accepted Answer

$\Delta H_{vap}$

Question 9

A patient accidentally ingests diethyl ether. Based on its vapor pressure curve, what is the most likely physiological effect compared to ingesting water?

Accepted Answer

Diethyl ether will evaporate more rapidly, potentially causing intoxication

Question 10

Which of the following best explains why ethylene glycol is used as antifreeze in car radiators?

Accepted Answer

It increases the boiling point and decreases the freezing point of water

Question 11

If the vapor pressure of water at 80°C is 355 mmHg, what is the boiling point of water at an atmospheric pressure of 355 mmHg?

Accepted Answer

80°C

Question 12

Which of the following would most likely increase the rate of evaporation of a liquid?

Accepted Answer

Increasing the temperature

Question 13

A chemist wants to separate a mixture of ethanol and water by distillation. Which property is most important for the separation?

Accepted Answer

Difference in boiling points

Question 14

Which of the following is true about the normal boiling point of a liquid?

Accepted Answer

It is the temperature at which the vapor pressure equals 1 atm

Question 15

If a liquid has a high vapor pressure at room temperature, what can you infer about its intermolecular forces?

Accepted Answer

They are weak

Question 16

Which of the following best describes the relationship between temperature and kinetic energy of molecules in a liquid?

Accepted Answer

As temperature increases, kinetic energy increases

Question 17

A solution of water and ethanol has a lower vapor pressure than pure ethanol. What is the most likely explanation?

Accepted Answer

Water forms hydrogen bonds with ethanol, reducing the number of molecules that can escape

Question 18

Which of the following is NOT a colligative property?

Accepted Answer

Density

Question 19

If the enthalpy of vaporization for water is $40.7$ kJ/mol, how much energy is required to vaporize $2.0$ mol of water at its boiling point?

Accepted Answer

$81.4$ kJ

General Chemistry Practice Final Exam Study Notes

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