SOLVED

21) The specific heat capacity of methane gas is 2.20 J/g-K. How many joules of heat are needed to raise the temperature of 5.00 g of methane from 36.0°C to 75.0°C? A) 88.6 J B) 429 J C) 1221 J D) 0.0113 J E) 22.9 J 22) The specific heat of copper is 0.385 J/(g ? °C). If 34.2 g of copper, initially at 24.0°C, absorbs 4.689 kJ, what will be the final temperature of the copper? A) 24.4°C B) 26.8°C C) 356°C D) 380°C 23) A sample of copper absorbs 43.6 kJ of heat, resulting in a temperature rise of 40.0°C, determine the mass (in kg) of the copper sample if the specific heat capacity of copper is 0.385 J/g°C. A) 2.83 kg B) 9.93 kg C) 1.89 kg D) 11.9 kg E) 5.46 kg 24) It takes 11.2 kJ of energy to raise the temperature of 145 g of benzene from 23.0°C to 68.0°C. What is the specific heat of benzene? A) 1.14 J/(g ? °C) B) 1.72 J/(g ? °C) C) 3.48 J/(g ? °C) D) 5.25 J/(g ? °C) 25) A 50.0-g sample of liquid water at 25.0°C is mixed with 29.0 g of water at 45.0°C. The final temperature of the water is ________°C. A) 102 B) 27.6 C) 35.0 D) 142 E) 32.3 26) What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g/ml by 7.80°C? (The specific heat of the solution is 3.74 J/g?K.) A) -7.43 kJ B) -12.51 kJ C) 8.20 kJ D) -9.12 kJ E) 6.51 kJ 27) The combustion of titanium with oxygen produces titanium dioxide: Ti(s) + (g) → (s) When 2.060 g of titanium is combusted in a bomb calorimeter, the temperature of the calorimeter increases from 25.00°C to 91.60°C. In a separate experiment, the heat capacity of the calorimeter is measured to be 9.84 kJ/K. The heat of reaction for the combustion of a mole of Ti in this calorimeter is ________ kJ/mol. A) 14.3 B) 19.6 C) -311 D) -0.154 E) -1.52 × 28) Identify what a bomb calorimeter measures. A) measures ΔH for aqueous solutions B) measures ΔE for combustion reactions C) measures ΔH for reduction solutions D) measures ΔT for aqueous solutions E) measures ΔE for oxidation reactions 29) Calculate the change in internal energy (ΔE) for a system that is absorbing 35.8 kJ of heat and is expanding from 8.00 to 24.0 L in volume at 1.00 atm. (Remember that 101.3 J = 1 L?atm) A) +51.8 kJ B) -15.8 kJ C) -16.6 kJ D) -29.3 kJ E) +34.2 kJ 30) When 0.455 g of anthracene, C14H10, is combusted in a bomb calorimeter that has a water jacket containing 500.0 g of water, the temperature of the water increases by 8.63°C. Assuming that the specific heat of water is 4.18 J/(g ? °C), and that the heat absorption by the calorimeter is negligible, estimate the enthalpy of combustion per mole of anthracene. A) +39.7 kJ/mol B) -39.7 kJ/mol C) -7060 kJ/mol D) -8120 kJ/mol