Heat Definition In Physics Quiz

1. How much heat is needed to warm 250.0 g of copper from 22° C to 98° C?

7315 J

2117 J

9433 J

79,420 J

To calculate the amount of heat needed to warm a substance, we can use the formula Q = mcΔT, where Q is the heat energy, m is the mass of the substance, c is the specific heat capacity, and ΔT is the change in temperature. In this case, we are given the mass of copper (250.0 g) and the temperature change (22°C to 98°C). Since the specific heat capacity of copper is approximately 0.39 J/g°C, we can calculate the heat energy by substituting the values into the formula: Q = (250.0 g)(0.39 J/g°C)(98°C - 22°C) = 7315 J. Therefore, the correct answer is 7315 J.

Explanation

To calculate the amount of heat needed to warm a substance, we can use the formula Q = mcΔT, where Q is the heat energy, m is the mass of the substance, c is the specific heat capacity, and ΔT is the change in temperature. In this case, we are given the mass of copper (250.0 g) and the temperature change (22°C to 98°C). Since the specific heat capacity of copper is approximately 0.39 J/g°C, we can calculate the heat energy by substituting the values into the formula: Q = (250.0 g)(0.39 J/g°C)(98°C - 22°C) = 7315 J. Therefore, the correct answer is 7315 J.

2. If 900 J of heat are added to 100.0 g of water at 25.0 °C. What is the final temperature of the water?

27.15 C

25.0 C

2.15 C

3.00 C

When heat is added to a substance, its temperature increases. The amount of heat required to raise the temperature of a substance can be calculated using the equation Q = mcΔT, where Q is the heat energy, m is the mass of the substance, c is the specific heat capacity, and ΔT is the change in temperature. In this case, we know that Q is 900 J, m is 100.0 g, and ΔT is the final temperature minus the initial temperature (final temperature - 25.0 °C). By rearranging the equation and solving for the final temperature, we can find that the final temperature is 27.15 °C.

Explanation

When heat is added to a substance, its temperature increases. The amount of heat required to raise the temperature of a substance can be calculated using the equation Q = mcΔT, where Q is the heat energy, m is the mass of the substance, c is the specific heat capacity, and ΔT is the change in temperature. In this case, we know that Q is 900 J, m is 100.0 g, and ΔT is the final temperature minus the initial temperature (final temperature - 25.0 °C). By rearranging the equation and solving for the final temperature, we can find that the final temperature is 27.15 °C.

3. Why does it require 5,511 J of heat energy to melt 16.5 g of ice?

4.18 J/g°C of heat energy is required as ice is converted from a solid to a liquid.

2.05 J/g°C of heat energy is required as ice is converted from a solid to a liquid.

The correct answer is 334 J/g of heat energy is absorbed by the ice as it is converted from a solid to a liquid. This is because the heat of fusion of ice is 334 J/g, which means that it takes 334 joules of energy to convert 1 gram of ice at 0°C to water at 0°C. Therefore, to melt 16.5 g of ice, it would require 16.5 g x 334 J/g = 5,511 J of heat energy.

Explanation

The correct answer is 334 J/g of heat energy is absorbed by the ice as it is converted from a solid to a liquid. This is because the heat of fusion of ice is 334 J/g, which means that it takes 334 joules of energy to convert 1 gram of ice at 0°C to water at 0°C. Therefore, to melt 16.5 g of ice, it would require 16.5 g x 334 J/g = 5,511 J of heat energy.

4. Which of the following is true when a substance is melting?

The temperature remains constant.

Both a solid and a gas can be present.

Heat is not required for the process since the temperature is constant.

The heat added is causing the particles to change from a high energy state to a low energy state.

When a substance is melting, the temperature remains constant because the heat being added is being used to break the bonds between the particles rather than increase the temperature. This is because during the melting process, the substance is transitioning from a solid to a liquid state, and this transition requires energy to break the intermolecular forces holding the particles together. As a result, the temperature remains constant until all the solid has melted and then starts increasing again.

Explanation

When a substance is melting, the temperature remains constant because the heat being added is being used to break the bonds between the particles rather than increase the temperature. This is because during the melting process, the substance is transitioning from a solid to a liquid state, and this transition requires energy to break the intermolecular forces holding the particles together. As a result, the temperature remains constant until all the solid has melted and then starts increasing again.

5. Is this equation an example of an exothermic or endothermic reaction: NaOH (s) + H₂O (l) --> NaOH (aq) + 21 J

Exothermic

Endothermic

Answer option 3

Answer option 4

The given equation represents the dissolution of solid NaOH in water, resulting in the formation of an aqueous solution of NaOH. The release of 21 J of energy indicates that the reaction is exothermic, as energy is being released into the surroundings.

Explanation

The given equation represents the dissolution of solid NaOH in water, resulting in the formation of an aqueous solution of NaOH. The release of 21 J of energy indicates that the reaction is exothermic, as energy is being released into the surroundings.

6. Which best explains the relationship between heat energy and temperature?

As heat energy decreases and temperature remains constant, condensation occurs.

As heat energy increases and temperature increases, freezing occurs.

As heat energy decreases and temperature remains constant, evaporation occurs.

As heat energy increases and temperature decreases, melting occurs.

As heat energy decreases, the molecules in a substance slow down and move closer together. This causes the substance to cool down and reach its dew point, which leads to condensation. The temperature remains constant because the heat energy is being released as the substance changes from a gas to a liquid. Therefore, the best explanation for the relationship between heat energy and temperature in this scenario is that as heat energy decreases and temperature remains constant, condensation occurs.

Explanation

As heat energy decreases, the molecules in a substance slow down and move closer together. This causes the substance to cool down and reach its dew point, which leads to condensation. The temperature remains constant because the heat energy is being released as the substance changes from a gas to a liquid. Therefore, the best explanation for the relationship between heat energy and temperature in this scenario is that as heat energy decreases and temperature remains constant, condensation occurs.

7. How much heat is given off when 27.0 g of steam condense to boiling water at 100°C?

61,020 J

9018 J

113 J

2,999 J

When steam condenses to boiling water, it releases heat energy. The amount of heat released can be calculated using the equation q = m × ΔHv, where q is the heat energy, m is the mass of the substance, and ΔHv is the heat of vaporization. In this case, the mass of the steam is given as 27.0 g. The heat of vaporization for water is approximately 2260 J/g. Plugging these values into the equation, we get q = 27.0 g × 2260 J/g = 61,020 J. Therefore, the correct answer is 61,020 J.

Explanation

When steam condenses to boiling water, it releases heat energy. The amount of heat released can be calculated using the equation q = m × ΔHv, where q is the heat energy, m is the mass of the substance, and ΔHv is the heat of vaporization. In this case, the mass of the steam is given as 27.0 g. The heat of vaporization for water is approximately 2260 J/g. Plugging these values into the equation, we get q = 27.0 g × 2260 J/g = 61,020 J. Therefore, the correct answer is 61,020 J.

8. An 8.80 g sample of metal is heated to 92.0 °C and then added to 14.77 g of water at 20.0 °C in an insulated calorimeter. At thermal equilibrium the temperature of the system was measured as 25.0 °C. What is the identity of the metal?

Titanium

Lead

Copper

Tin

not-available-via-ai

Explanation

not-available-via-ai

9. The graph below below shows a substance heating from 40 C to 140 C. If 70 kJ of heat are removed from the substance when it is at 140°C, what will be the state and temperature of the substance?

Liquid at 60 C.

Liquid at 10 C.

Gas at 100 C.

Gas at 120 C.

The graph shows that the substance is initially at 40°C and then heated to 140°C. After reaching 140°C, 70 kJ of heat are removed from the substance. Based on the graph, the substance remains in the liquid phase throughout the heating process. Therefore, when 70 kJ of heat are removed, the substance will still be in the liquid state. Looking at the graph, the temperature at which the substance is in the liquid state after the heat removal is 60°C. Therefore, the substance will be in the liquid state at 60°C.

Explanation

The graph shows that the substance is initially at 40°C and then heated to 140°C. After reaching 140°C, 70 kJ of heat are removed from the substance. Based on the graph, the substance remains in the liquid phase throughout the heating process. Therefore, when 70 kJ of heat are removed, the substance will still be in the liquid state. Looking at the graph, the temperature at which the substance is in the liquid state after the heat removal is 60°C. Therefore, the substance will be in the liquid state at 60°C.

10. What causes the process of perspiration to be cooling for human skin?

It involves evaporation and is endothermic.

It involves evaporation and is exothermic.

It involves condensation and is endothermic.

It involves condensation.

Perspiration, or sweating, is a cooling process for human skin because it involves evaporation. When sweat evaporates from the skin surface, it takes heat energy with it, resulting in a cooling effect. This process is endothermic because it absorbs heat from the body in order to convert the liquid sweat into a gas during evaporation.

Explanation

Perspiration, or sweating, is a cooling process for human skin because it involves evaporation. When sweat evaporates from the skin surface, it takes heat energy with it, resulting in a cooling effect. This process is endothermic because it absorbs heat from the body in order to convert the liquid sweat into a gas during evaporation.