Question 1

Which of the following processes is an exothermic physical change?

Accepted Answer

Freezing is an exothermic process because it involves the release of heat to the surroundings as a substance changes from a liquid to a solid state.

Question 2

Formaldehyde, commonly used to preserve biological specimens, is shown in the structure below.If liquid formaldehyde is boiled, which of the following illustrations BEST depicts how formaldehyde looks in the resulting vapor?

Accepted Answer

The answer of Formaldehyde, commonly used to preserve biological specimens,...

Question 3

On a cool morning (12 °C), a balloon is filled with 1.5 L of helium.By mid-afternoon, the temperature has soared to 32 °C.What is the new volume of the balloon?

Accepted Answer

The volume of the balloon at the new temperature can be found using Charles's Law, which states that $V_1/T_1 = V_2/T_2$ when the pressure is constant. First, convert temperatures to Kelvin by adding 273.15: $T_1 = 12 + 273.15 = 285.15 K$ and $T_2 = 32 + 273.15 = 305.15 K$. Then, solve for $V_2$: $V_2 = V_1 \times (T_2 / T_1) = 1.5 \times (305.15 / 285.15) \approx 1.6 L$.

Question 4

Henry's constant for halothane, an anesthetic, is higher than that of ether.Which anesthetic is faster acting?

Accepted Answer

A higher Henry's constant indicates that halothane is less soluble in blood, allowing it to diffuse more quickly into tissues, leading to faster onset of action.

Question 5

How are vaporization and evaporation similar?

Accepted Answer

Both vaporization and evaporation describe the process where a liquid turns into a gas. Vaporization can be a more general term that includes boiling (which is rapid and occurs throughout the liquid) and evaporation (which is slower and occurs at the surface of the liquid, not necessarily at the boiling point).

Question 6

Which compound has the lowest boiling point?

Accepted Answer

Oxygen (O₂) is a nonpolar diatomic molecule with weak dispersion forces, resulting in a very low boiling point compared to the other compounds listed.

Question 7

A narrow tube on a road bike should be inflated to about 100 psi.What is this pressure in atmospheres?

Accepted Answer

1 atmosphere (atm) is approximately equal to 101.325 kilopascals (kPa) or about 14.7 pounds per square inch (psi). Therefore, 100 psi is about 100 / 14.7 ≈ 6.8 atm, which rounds to approximately 7 atm.

Question 8

Which of the following statements BEST describes specific heat?

Accepted Answer

Specific heat is defined as the amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius (or Kelvin). This property is intrinsic to each material and determines how it reacts to heat input.

Question 9

A nitrogen bubble with a volume of 0.0050 mL forms in the joint of a scuba diver as she ascends rapidly from a pressure of 4.1 atm to the surface, with a pressure of 1.0 atm.What is the volume of the bubble at the surface?

Accepted Answer

The volume of the nitrogen bubble at the surface can be calculated using Boyle's Law, which states that the pressure of a gas times its volume is constant at constant temperature (P1V1 = P2V2). Given the initial pressure (P1 = 4.1 atm) and volume (V1 = 0.0050 mL) and the final pressure (P2 = 1.0 atm), we can solve for the final volume (V2). Rearranging the equation gives V2 = (P1V1)/P2 = (4.1 atm * 0.0050 mL) / 1.0 atm = 0.0205 mL, which rounds to 0.021 mL.

Question 10

Two sealed boxes are filled with gas.The first box contains more molecules moving faster and therefore has a higher pressure.The second box contains fewer molecules moving slower and therefore has a lower pressure.Why does the first box have a higher pressure?

Accepted Answer

The more collisions against the side of the box, the higher the pressure.

Question 11

Which of the following is the common treatment for the bends?

Accepted Answer

The bends, also known as decompression sickness, is treated by slow depressurization in a hyperbaric chamber. This process allows the body to safely eliminate excess gases, such as nitrogen, that have dissolved in the blood and tissues under high pressure.

Question 12

What type of change in pressure causes the bends, and why?

Accepted Answer

The bends, also known as decompression sickness, occur when there is a rapid decrease in pressure, causing nitrogen that has dissolved in the bloodstream under high pressure to rapidly come out of solution and form bubbles in the blood and tissues. This can cause various symptoms ranging from joint pain and rashes to paralysis and death.

Question 13

A balloon at STP is heated.Which of the following statements about the relationship between volume and temperature is TRUE?

Accepted Answer

According to Charles's Law, the volume of a gas is directly proportional to its temperature when pressure is held constant. Therefore, if the temperature of a gas increases, its volume also increases, assuming the pressure and the amount of gas remain constant.

Question 14

What change of phase is represented by B on the heating curve?

Accepted Answer

The answer of What change of phase is represented by...

Question 15

What occurs over the course of the physical change illustrated below?

Accepted Answer

The answer of What occurs over the course of the...

Question 16

What is the volume of 2.01 × 10^-3 mol of oxygen at STP?

Accepted Answer

At STP (Standard Temperature and Pressure), 1 mole of any gas occupies 22.4 liters. The given amount of oxygen is 2.01 × 10^-3 moles. To find the volume, multiply the moles by the volume occupied by 1 mole at STP: $2.01 \times 10^{-3} \text{ moles} \times 22.4 \text{ L/mole} = 4.50 \times 10^{-2} \text{ L}$.

Question 17

How many calories of heat are required to raise the temperature of 15 g water (specific heat = 1.00 cal/g·°C)from 25 °C and 42 °C?

Accepted Answer

The answer of How many calories of heat are required...

Question 18

To accomplish the change of phase shown in the diagram below, you could

Accepted Answer

The answer of To accomplish the change of phase shown...

Question 19

Which of the following statements BEST describes pressure?

Accepted Answer

Pressure is defined as the force applied per unit area. This is why option D is the best description of pressure.

Question 20

Why is water (H₂O)a liquid at room temperature whereas methane (CH₄)is a gas?

Accepted Answer

Water forms hydrogen bonds due to the presence of hydrogen atoms bonded to a highly electronegative oxygen atom, which gives it a higher boiling point and makes it a liquid at room temperature. Methane, on the other hand, can only form weaker dispersion forces, which is why it is a gas at room temperature.

Quiz 7: Changes of State and Gas Laws

Which of the following processes is an exothermic physical change?

Formaldehyde, commonly used to preserve biological specimens, is shown in the structure below.If liquid formaldehyde is boiled, which of the following illustrations BEST depicts how formaldehyde looks in the resulting vapor?

On a cool morning (12 °C) , a balloon is filled with 1.5 L of helium.By mid-afternoon, the temperature has soared to 32 °C.What is the new volume of the balloon?

Henry's constant for halothane, an anesthetic, is higher than that of ether.Which anesthetic is faster acting?

How are vaporization and evaporation similar?

Which compound has the lowest boiling point?

A narrow tube on a road bike should be inflated to about 100 psi.What is this pressure in atmospheres?

Which of the following statements BEST describes specific heat?

A nitrogen bubble with a volume of 0.0050 mL forms in the joint of a scuba diver as she ascends rapidly from a pressure of 4.1 atm to the surface, with a pressure of 1.0 atm.What is the volume of the bubble at the surface?

Two sealed boxes are filled with gas.The first box contains more molecules moving faster and therefore has a higher pressure.The second box contains fewer molecules moving slower and therefore has a lower pressure.Why does the first box have a higher pressure?

Which of the following is the common treatment for the bends?

What type of change in pressure causes the bends, and why?

A balloon at STP is heated.Which of the following statements about the relationship between volume and temperature is TRUE?

What change of phase is represented by B on the heating curve?

What occurs over the course of the physical change illustrated below?

What is the volume of 2.01 × 10^-3 mol of oxygen at STP?

How many calories of heat are required to raise the temperature of 15 g water (specific heat = 1.00 cal/g·°C) from 25 °C and 42 °C?

To accomplish the change of phase shown in the diagram below, you could

Which of the following statements BEST describes pressure?

Why is water (H₂O) a liquid at room temperature whereas methane (CH₄) is a gas?

Quiz 7: Changes of State and Gas Laws

Which of the following processes is an exothermic physical change?

Formaldehyde, commonly used to preserve biological specimens, is shown in the structure below.If liquid formaldehyde is boiled, which of the following illustrations BEST depicts how formaldehyde looks in the resulting vapor?

On a cool morning (12 °C) , a balloon is filled with 1.5 L of helium.By mid-afternoon, the temperature has soared to 32 °C.What is the new volume of the balloon?

Henry's constant for halothane, an anesthetic, is higher than that of ether.Which anesthetic is faster acting?

How are vaporization and evaporation similar?

Which compound has the lowest boiling point?

A narrow tube on a road bike should be inflated to about 100 psi.What is this pressure in atmospheres?

Which of the following statements BEST describes specific heat?

A nitrogen bubble with a volume of 0.0050 mL forms in the joint of a scuba diver as she ascends rapidly from a pressure of 4.1 atm to the surface, with a pressure of 1.0 atm.What is the volume of the bubble at the surface?

Two sealed boxes are filled with gas.The first box contains more molecules moving faster and therefore has a higher pressure.The second box contains fewer molecules moving slower and therefore has a lower pressure.Why does the first box have a higher pressure?

Which of the following is the common treatment for the bends?

What type of change in pressure causes the bends, and why?

A balloon at STP is heated.Which of the following statements about the relationship between volume and temperature is TRUE?

What change of phase is represented by B on the heating curve?

What occurs over the course of the physical change illustrated below?

What is the volume of 2.01 × 10-3 mol of oxygen at STP?

How many calories of heat are required to raise the temperature of 15 g water (specific heat = 1.00 cal/g·°C) from 25 °C and 42 °C?

To accomplish the change of phase shown in the diagram below, you could

Which of the following statements BEST describes pressure?

Why is water (H2O) a liquid at room temperature whereas methane (CH4) is a gas?

What is the volume of 2.01 × 10^-3 mol of oxygen at STP?

Why is water (H₂O) a liquid at room temperature whereas methane (CH₄) is a gas?