Q: Given 100 g of ice at $$-10.0\ ^\circ\mathrm{C}$$, which equation would you use to calculate the heat required to warm the ice to $$0.0\ ^\circ\mathrm{C}$$?

$$q = m \times C_{\text{ice}} \times \Delta T$$

Q: If the heat capacity of ice is $$2.08\ \mathrm{J/g\cdot K}$$, how much heat is required to warm 100 g of ice from $$-10.0\ ^\circ\mathrm{C} to$$ $$0.0\ ^\circ\mathrm{C}$$?

$$q = 100 \times 2.08 \times 10 = 2080\ \mathrm{J}$$

Q: Which formula would you use to calculate the heat required to convert liquid water at $$100.0\ ^\circ\mathrm{C} to $$steam at $$100.0\ ^\circ\mathrm{C}$$?

$$q = m \times \Delta H_{\text{vap}}$$

Q: If the heat capacity of steam is $$1.84\ \mathrm{J/g\cdot K}$$, how much heat is required to heat 100 g of steam from $$100.0\ ^\circ\mathrm{C} to$$ $$110.0\ ^\circ\mathrm{C}$$?

$$q = 100 \times 1.84 \times 10 = 1840\ \mathrm{J}$$

Question 1

Which of the following best describes what happens to the temperature of a substance during a phase change, as shown in the heating curve diagram?

Accepted Answer

The temperature remains constant until the phase change is complete.

Question 2

Given 100 g of ice at $$-10.0\ ^\circ\mathrm{C}$$, which equation would you use to calculate the heat required to warm the ice to $$0.0\ ^\circ\mathrm{C}$$?

Accepted Answer

$$q = m 	imes C_{	ext{ice}} 	imes \Delta T$$

Question 3

What is the correct sequence of steps to calculate the total heat required to convert 100 g of ice at $$-10.0\ ^\circ\mathrm{C} to $$steam at $$110.0\ ^\circ\mathrm{C}$$?

Accepted Answer

Heat ice to $$0.0\ ^\circ\mathrm{C}$$, melt ice, heat water to $$100.0\ ^\circ\mathrm{C}$$, vaporize water, heat steam to $$110.0\ ^\circ\mathrm{C}$$

Question 4

If the heat capacity of ice is $$2.08\ \mathrm{J/g\cdot K}$$, how much heat is required to warm 100 g of ice from $$-10.0\ ^\circ\mathrm{C} to$$ $$0.0\ ^\circ\mathrm{C}$$?

Accepted Answer

$$q = 100 	imes 2.08 	imes 10 = 2080\ \mathrm{J}$$

Question 5

During which segment of the heating curve does the temperature remain constant while heat is added?

Accepted Answer

During the melting of ice at $$0\ ^\circ\mathrm{C}$$

Question 6

Which formula would you use to calculate the heat required to convert liquid water at $$100.0\ ^\circ\mathrm{C} to $$steam at $$100.0\ ^\circ\mathrm{C}$$?

Accepted Answer

$$q = m 	imes \Delta H_{	ext{vap}}$$

Question 7

A student claims that the temperature of water increases during boiling. Based on the heating curve, is this correct?

Accepted Answer

No, the temperature remains constant during boiling.

Question 8

If the heat capacity of steam is $$1.84\ \mathrm{J/g\cdot K}$$, how much heat is required to heat 100 g of steam from $$100.0\ ^\circ\mathrm{C} to$$ $$110.0\ ^\circ\mathrm{C}$$?

Accepted Answer

$$q = 100 	imes 1.84 	imes 10 = 1840\ \mathrm{J}$$

Question 9

Which of the following best explains why the temperature does not change during the melting of ice?

Accepted Answer

The heat is used to break the intermolecular forces between water molecules.

Question 10

A hospital needs to sterilize equipment using steam at $$110.0\ ^\circ\mathrm{C}. If $$the equipment is initially at $$0.0\ ^\circ\mathrm{C}$$, which steps must be considered to calculate the total heat required to convert water at $$0.0\ ^\circ\mathrm{C} to $$steam at $$110.0\ ^\circ\mathrm{C}$$?

Accepted Answer

Heat water to $$100.0\ ^\circ\mathrm{C}$$, vaporize water, heat steam to $$110.0\ ^\circ\mathrm{C}$$

Question 11

Which segment of the heating curve represents the phase change from liquid water to steam?

Accepted Answer

The horizontal segment at $$100\ ^\circ\mathrm{C}$$

Question 12

Which of the following is the correct formula to calculate the heat required to melt 100 g of ice at $$0.0\ ^\circ\mathrm{C}$$? (Assume $$\Delta H_{	ext{fus}} is $$given.)

Accepted Answer

$$q = m 	imes \Delta H_{	ext{fus}}$$

Question 13

Why is the heat capacity of steam lower than that of liquid water?

Accepted Answer

Steam molecules have weaker intermolecular forces, so less energy is needed to increase their temperature.

Question 14

A chef wants to quickly melt ice for a recipe. Which process will require the most energy: heating ice from $$-10.0\ ^\circ\mathrm{C} to$$ $$0.0\ ^\circ\mathrm{C}$$, melting ice at $$0.0\ ^\circ\mathrm{C}$$, or heating water from $$0.0\ ^\circ\mathrm{C} to$$ $$10.0\ ^\circ\mathrm{C}$$? (Assume $$\Delta H_{	ext{fus}} is $$much larger than the heat capacities.)

Accepted Answer

Melting ice at $$0.0\ ^\circ\mathrm{C}$$

Question 15

Which of the following best describes the energy changes during the segment labeled 'D to E' on the heating curve?

Accepted Answer

The temperature remains constant as water vaporizes.

Heating and Cooling Curves: Calculating Heat for Phase Changes

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