Question 1

How much heat is required to raise the temperature of 1.00 gram of water from absolute zero,  , to  ?

Accepted Answer

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Question 2

How much heat is required to raise the temperature of 100,000 grams of iron by 30°C?

Accepted Answer

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Question 3

To impart a hickory flavor to a roasted turkey, a cook places a pot of water containing hickory chips in an oven with the turkey. Why does the turkey take longer than expected to cook?

Accepted Answer

Much of the heat from the oven is consumed in changing the phase of the water from liquid to vapor, which requires a significant amount of energy (latent heat of vaporization). This process reduces the amount of heat available to cook the turkey, thereby extending the cooking time.

Question 4

A walnut stuck to a pin is burned beneath a can containing 100.0 grams of water at 21°C. After the walnut has completely burned, the water's final temperature is a warmer 28°C. How much heat energy arose from the burning walnut?

Accepted Answer

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Question 5

Why is it that in cold winters a tub of water placed in a farmer's canning cellar helps prevent canned food from freezing?

Accepted Answer

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Question 6

Which of the following contains the least heat energy?

Accepted Answer

Ice at 0°C has the least heat energy as it has a low temperature and is in a solid state which means its molecules have low kinetic energy compared to the other options.

Question 7

If the winds at the latitude of San Francisco and Washington, D.C., were from the east rather than from the west, why might San Francisco be able to grow cherry trees and Washington, D.C. palm trees?

Accepted Answer

The explanation for D correctly accounts for the influence of oceanic temperatures on local climates. The Pacific Ocean's moderating effect currently keeps San Francisco's climate mild, allowing for the growth of cherry trees. If winds were from the east, Washington, D.C. would benefit from the warming effect of the Atlantic, potentially making it suitable for palm trees, while San Francisco would receive cooler, drier air from the interior, like Nevada, affecting its ability to grow certain plants.

Question 8

Why does transforming water from 100°C liquid to 100°C gas require much more energy than to raise the temperature of the same amount of water from absolute zero all the way to 100°C liquid?

Accepted Answer

Transforming water from 100°C liquid to 100°C gas requires breaking the hydrogen bonds between the liquid molecules. This requires a significant amount of energy, as hydrogen bonds are strong intermolecular forces. In contrast, raising the temperature of the water from absolute zero to 100°C only requires imparting kinetic energy to the water molecules themselves, which is a much easier task. Thus, transforming water from liquid to gas requires much more energy than raising the temperature of the same amount of water from absolute zero to 100°C liquid. Option A is incorrect because it describes the process of raising the temperature of water from solid to liquid, which is not relevant to the question. Option B and D are both incorrect because they are false statements.

Question 9

Is the food compartment in a refrigerator cooled by evaporation or condensation of the refrigerating coolant?

Accepted Answer

The food compartment of a refrigerator is cooled by the evaporation of the refrigerating fluid. This process absorbs heat from the surroundings (the inside of the refrigerator), thereby cooling it.

Question 10

Which of the following statements regarding a phase change is NOT true?

Accepted Answer

During a phase change, the amount of heat energy being absorbed or released by the sample does not stay the same. This is because energy is required to overcome the intermolecular forces holding the sample in its current phase, which is released when the sample transitions to a new phase. Therefore, the amount of heat energy changes during a phase change.

Question 11

Which of the following contains the most heat energy?

Accepted Answer

Steam at 100°C has the most heat energy because it has reached its boiling point and therefore has absorbed the most amount of heat energy to undergo the phase change from liquid to gas. The other options are either at a lower temperature or haven't undergone a phase change, which means they have less heat energy.

Question 12

Suppose 4 g of water at 100°C is spread over a large surface so that 1 g evaporates rapidly. If evaporation of the 1 gram takes 2,259 joules from the remaining 3 g of water and no other heat transfer takes place, what are the temperature and phase of the remaining 3 g once the 1 gram is completely evaporated?

Accepted Answer

From the given information, we know that 1 g of water at 100°C is evaporated, which requires 2259 J of energy. This energy comes from the remaining 3 g of water. The heat required to vaporize 1 g of water at 100°C is:

q = mL = (1 g)(2.26 J/g·°C)(100°C) = 226 J

Therefore, the remaining 3 g of water loses:

Q = (226 J/g)(1 g) = 226 J

Thus, the remaining 3 g of water lose a total of 2259 J + 226 J = 2485 J. This energy loss causes a drop in temperature of the 3 g of water.

The specific heat capacity of water is 4.18 J/g·°C. Therefore, the change in temperature is given by:

Q = mcΔT

-2485 J = (3 g)(4.18 J/g·°C)ΔT

ΔT = -187.41°C

This means that the temperature of the remaining 3 g of water drops to -87.41°C. Since this is below the freezing point of water (0°C), the remaining 3 g of water will freeze and turn into ice. Therefore, the answer is D, the remaining 3 g will turn to 0°C ice.

Question 13

Maple syrup is made from the sap of the sugar maple tree. Why does is take so much energy to make maple syrup?

Accepted Answer

Producing maple syrup requires boiling away most of the water from the sap. The resulting concentrated solution is maple syrup. A lot of energy is required to boil away the water.

Question 14

By how much will the temperature of 5.0 grams of water increase upon the addition of 230 joules of heat?

Accepted Answer

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Question 15

If the heat of melting of a sample is 135 J/g, what would the heat of freezing for the sample be?

Accepted Answer

The heat of freezing for a sample is the negative of the heat of melting because the processes are opposites. If melting absorbs 135 J/g, freezing releases 135 J/g, hence -135 J/g.

Question 16

Which of the following would cause the worst burn?

Accepted Answer

Steam at 100°C has a higher heat capacity and latent heat of vaporization compared to water at the same temperature. This means that it can transfer more energy to the skin, causing a more severe burn.

Question 17

If the heat of melting of a sample is 135 J/g, how much heat would be required to melt 5.00 grams of material?

Accepted Answer

We can use the formula:

heat required = heat of melting x mass

Plugging in the values:

heat required = 135 J/g x 5.00 g
heat required = 675 J

Therefore, the heat required to melt 5.00 grams of material is 675 J, which corresponds to choice A.

Question 18

Antarctica, which is mostly ice, is much colder than the Arctic, which is a mixture of ice and water. Why?

Accepted Answer

A, D- A) The liquid water in the Arctic Ocean absorbs and releases heat, moderating temperature fluctuations.- D) The specific heat capacity of ice is lower than that of water, meaning ice can change temperature more easily than water.

Question 19

A great deal of heat is released when liquid water freezes. Why doesn't this heat simply remelt the ice?

Accepted Answer

The heat released during the freezing process is radiated outwards into the surrounding environment rather than being absorbed back into the ice, preventing the ice from melting.

Question 20

Relative to pure water, an aqueous sugar solution ________.

Accepted Answer

When sugar is added to water, the freezing point of the resulting solution is lowered due to a phenomenon called freezing point depression. This is because the sugar molecules disrupt the organization of the water molecules, making it more difficult for ice crystals to form. As a result, the solution must be cooled to a lower temperature before freezing can occur. Therefore, a sugar solution has a lower freezing point than pure water.

Quiz 8: How Water Behaves

How much heat is required to raise the temperature of 1.00 gram of water from absolute zero, , to ?