A bag of chocolate candy has 220 Cal. How much energy is this in kJ? Answer: a

A bag of chocolate candy has 220 Cal. How much energy is this in kJ? Answer: a

heat (q) and work (w) are both positive. For a system that gains thermal energy and does work on the surroundings, heat (q) and work (w) are both positive. heat (q) is positive and work (w) is negative. heat (q) is negative and work (w) is positive. heat (q) and work (w) are both negative. Answer: b

heat (q) and work (w) are both positive. For a system that gains thermal energy and does work on the surroundings, heat (q) and work (w) are both positive. heat (q) is positive and work (w) is negative. heat (q) is negative and work (w) is positive. heat (q) and work (w) are both negative. Answer: b

Calculate the internal energy, ΔE, for a system that does 422 J of work and loses 227 J of energy as heat. + 649 J – 649 J 0 J – 195 J + 195 J Answer: b

Calculate the internal energy, ΔE, for a system that does 422 J of work and loses 227 J of energy as heat. + 649 J – 649 J 0 J – 195 J + 195 J Answer: b

A 3. 54 g piece of aluminum is heated to 96 A 3.54 g piece of aluminum is heated to 96.2 ºC and allowed to cool to room temperature, 22.5 ºC. Calculate the heat (in kJ) associated with the cooling process. The specific heat of aluminum is 0.903 J/ g · K. + 0.236 – 236 + 236 – 0.236 – 0.638 Answer: d

A 3. 54 g piece of aluminum is heated to 96 A 3.54 g piece of aluminum is heated to 96.2 ºC and allowed to cool to room temperature, 22.5 ºC. Calculate the heat (in kJ) associated with the cooling process. The specific heat of aluminum is 0.903 J/ g · K. + 0.236 – 236 + 236 – 0.236 – 0.638 Answer: d

A 1. 5 g iron nail is heated to 95 A 1.5 g iron nail is heated to 95.0 °C and placed into a beaker of water. Calculate the heat gained by the water if the final equilibrium temperature is 57.8 ° C. The specific heat capacity of iron = 0.449 J/ g ° C, and the specific heat capacity of water = 4.18 J/ g ° C. 6.0 J 25 J –25 J 39 J – 39 J Answer: b

A 1. 5 g iron nail is heated to 95 A 1.5 g iron nail is heated to 95.0 °C and placed into a beaker of water. Calculate the heat gained by the water if the final equilibrium temperature is 57.8 ° C. The specific heat capacity of iron = 0.449 J/ g ° C, and the specific heat capacity of water = 4.18 J/ g ° C. 6.0 J 25 J –25 J 39 J – 39 J Answer: b

None; all will be at the same temperature. Identical amounts of heat are applied to 50 g blocks of lead, silver, and copper, all at an initial temperature of 25 °C. Which block will have the largest increase in temperature? Lead Silver Copper None; all will be at the same temperature. Answer: c

None; all will be at the same temperature. Identical amounts of heat are applied to 50 g blocks of lead, silver, and copper, all at an initial temperature of 25 °C. Which block will have the largest increase in temperature? Lead Silver Copper None; all will be at the same temperature. Answer: c

50.0 g of water at 22 °C is mixed with 125 g of water initially at 36 ° C. What is the final temperature of the water after mixing, assuming no heat is lost to the surroundings? 29 °C 42 ° C 33 ° C 31 ° C 36 ° C Answer: c

50.0 g of water at 22 °C is mixed with 125 g of water initially at 36 ° C. What is the final temperature of the water after mixing, assuming no heat is lost to the surroundings? 29 °C 42 ° C 33 ° C 31 ° C 36 ° C Answer: c

How much work is done when a container expands 2 How much work is done when a container expands 2.55 L against an external pressure of 1.50 atm? 101.3 J = 1 L atm +376 J –376 J +387 J –387 J Answer: d

How much work is done when a container expands 2 How much work is done when a container expands 2.55 L against an external pressure of 1.50 atm? 101.3 J = 1 L atm +376 J –376 J +387 J –387 J Answer: d

A 4.25 g sample of cyclohexane (C6H12) is combusted in a bomb calorimeter with a total heat capacity of 5.86 kJ/ ºC. The temperature of the calorimeter increases from 23.5 ºC to 39.8 ºC. What is the heat of combustion for cyclohexane in kJ/ mol? – 95.5 + 95.5 – 1890 + 1890 – 22.5 Answer: c

A 4.25 g sample of cyclohexane (C6H12) is combusted in a bomb calorimeter with a total heat capacity of 5.86 kJ/ ºC. The temperature of the calorimeter increases from 23.5 ºC to 39.8 ºC. What is the heat of combustion for cyclohexane in kJ/ mol? – 95.5 + 95.5 – 1890 + 1890 – 22.5 Answer: c

In a coffee cup calorimetry experiment, 50. 0 mL of 0 In a coffee cup calorimetry experiment, 50.0 mL of 0.100 M NaOH is added to 50.0 mL of 0.100 M HCl. The temperature of the solution increased by 14.9 °C. Calculate ΔH for the reaction. Use 1.00 g/ mL as the density of the solution and 4.18 J/ g ° C as the specific heat capacity. 1.25 kJ/ mol 6.23 kJ/ mol 31.0 kJ/ mol 1250 kJ/ mol 6230 kJ/ mol Answer: d

In a coffee cup calorimetry experiment, 50. 0 mL of 0 In a coffee cup calorimetry experiment, 50.0 mL of 0.100 M NaOH is added to 50.0 mL of 0.100 M HCl. The temperature of the solution increased by 14.9 °C. Calculate ΔH for the reaction. Use 1.00 g/ mL as the density of the solution and 4.18 J/ g ° C as the specific heat capacity. 1.25 kJ/ mol 6.23 kJ/ mol 31.0 kJ/ mol 1250 kJ/ mol 6230 kJ/ mol Answer: d

Which of the following statements about enthalpy is FALSE? The value of ΔH for a chemical reaction is the amount of heat absorbed or evolved in the reaction under conditions of constant pressure. An endothermic reaction has a positive ΔH and absorbs heat from the surroundings. An endothermic reaction feels cold to the touch. An exothermic reaction has a negative ΔH and gives off heat to the surroundings. An exothermic reaction feels warm to the touch. Statements (a), (b), and (c) are all false statements. Statements (a), (b), and (c) are all true statements. Answer: e

Which of the following statements about enthalpy is FALSE? The value of ΔH for a chemical reaction is the amount of heat absorbed or evolved in the reaction under conditions of constant pressure. An endothermic reaction has a positive ΔH and absorbs heat from the surroundings. An endothermic reaction feels cold to the touch. An exothermic reaction has a negative ΔH and gives off heat to the surroundings. An exothermic reaction feels warm to the touch. Statements (a), (b), and (c) are all false statements. Statements (a), (b), and (c) are all true statements. Answer: e

Use Hess’s Law to determine ΔH for the following target reaction Use Hess’s Law to determine ΔH for the following target reaction. ½ N2 (g) + ½ O2 (g) → NO (g) ΔH = 90.3 kJ NO (g) + ½ Cl2 (g) → NOCl (g) ΔH = –38.6 kJ 2 NOCl (g) → N2 (g) + O2 (g) + Cl2 (g) ΔH = ? –51.7 kJ 51.7 kJ –103.4 kJ 103.4 kJ 142.0 kJ Answer: c

Use Hess’s Law to determine ΔH for the following target reaction Use Hess’s Law to determine ΔH for the following target reaction. ½ N2 (g) + ½ O2 (g) → NO (g) ΔH = 90.3 kJ NO (g) + ½ Cl2 (g) → NOCl (g) ΔH = –38.6 kJ 2 NOCl (g) → N2 (g) + O2 (g) + Cl2 (g) ΔH = ? –51.7 kJ 51.7 kJ –103.4 kJ 103.4 kJ 142.0 kJ Answer: c

Which of the following has a negative value of ΔH? The combustion of gasoline The melting of snow The evaporation of ethanol The sublimation of CO2 at room temperature All of the above have positive ΔH values. Answer: a

Which of the following has a negative value of ΔH? The combustion of gasoline The melting of snow The evaporation of ethanol The sublimation of CO2 at room temperature All of the above have positive ΔH values. Answer: a

Ethanol is used as an additive in many fuels today Ethanol is used as an additive in many fuels today. What is ΔHºrxn (kJ) for the combustion of ethanol? 2 C2H5OH (l ) + 6 O2 (g) → 4 CO2 (g) + 6 H2O (l ) – 401.7 + 401.7 –2469 + 2734 – 2734   ΔHºf (kJ/ mol) C2H5OH (l) –277.6 CO2 (g) –393.5 H2O (g) –241.8 H2O (l) –285.8 Answer: e

Ethanol is used as an additive in many fuels today Ethanol is used as an additive in many fuels today. What is ΔHºrxn (kJ) for the combustion of ethanol? 2 C2H5OH (l ) + 6 O2 (g) → 4 CO2 (g) + 6 H2O (l ) – 401.7 + 401.7 –2469 + 2734 – 2734   ΔHºf (kJ/ mol) C2H5OH (l) –277.6 CO2 (g) –393.5 H2O (g) –241.8 H2O (l) –285.8 Answer: e

The main engines of the space shuttle burn hydrogen to produce water The main engines of the space shuttle burn hydrogen to produce water. How much heat (in kJ) is associated with this process if 1.32 × 105 kg of liquid H2 is burned? 2 H2 (l ) + O2 (l ) → 2 H2O (l ) ΔHºrxn = – 571.6 kJ – 571.6 – 285.8 – 1.87 × 1010 – 3.74 × 1010 – 7.55 × 107 Answer: c

The main engines of the space shuttle burn hydrogen to produce water The main engines of the space shuttle burn hydrogen to produce water. How much heat (in kJ) is associated with this process if 1.32 × 105 kg of liquid H2 is burned? 2 H2 (l ) + O2 (l ) → 2 H2O (l ) ΔHºrxn = – 571.6 kJ – 571.6 – 285.8 – 1.87 × 1010 – 3.74 × 1010 – 7.55 × 107 Answer: c

What is one effect of global warming? Heightened storm severity More floods and droughts Rising sea levels Changes in habitats of some animals All of the above Answer: e

What is one effect of global warming? Heightened storm severity More floods and droughts Rising sea levels Changes in habitats of some animals All of the above Answer: e