Ap chem Qs 3

A 1.0 g sample of a cashew was burned in a calorimeter containing 1000. g of water, and the temperature of the water changed from 20.0°C to 25.0°C. In another experiment, a 3.0 g sample of a marshmallow was burned in a calorimeter containing 2000. g of water, and the temperature of the water changed from 25.0°C to 30.0°C. Based on the data, which of the following can be concluded about the energy content for 1.0 g of each of the two substances? (The specific heat of water is 4.2 J/(g⋅°C).)

The combustion of 1.0 g of cashew releases more energy than the combustion of 1.0 g of marshmallow.

Based on the information in the table above, which of the following expressions gives the approximate ΔH° for the reaction represented by the following balanced chemical equation? Fe2O3(s)+3CO(g)→2Fe(s)+3CO2(g)

ΔH°rxn=[2(0kJ/mol)+3(−394kJ/mol)]−[(−826kJ/mol)+3(−111kJ/mol)] Δ H ° r x n = [ 2 ( 0 kJ/mol ) + 3 ( − 394 kJ/mol ) ] − [ ( − 826 kJ/mol ) + 3 ( − 111 kJ/mol ) ]

2H2S(g)+3O2(g)→2H2O(l)+2SO2(g)ΔH°=−1120kJ/molrxn Based on the reaction represented by the chemical equation shown above, what is the amount of heat released when 4.00mol of H2S(g) reacts with 9.00mol of O2(g)?

-2240 kJ

AgNO3(aq) + NaC1(aq)→ AgC1(s) + NaNO3(aq) A g N O 3 ( a q ) + N a C 1 ( a q ) → A g C 1 ( s ) + N a N O 3 ( a q ) In an experiment a student mixes a 50.0 mL sample of 0.100 M AgNO3(aq) with a 50.0 mL sample of 0.100 M NaCl(aq) at 20.0°C in a coffee-cup calorimeter. Which of the following is the enthalpy change of the precipitation reaction represented above if the final temperature of the mixture is 21.0°C? (Assume that the total mass of the mixture is 100. g and that the specific heat capacity of the mixture is 4.2 J/(g °C).)

0.42 kJ/molrxn

½ H2(g) + ½ I2(s) → HI(g) ∆H = 26 kJ/molrxn ½ H2(g) + ½ I2(g) → HI(g) ∆H = -5.0 kJ/molrxn Based on the information above, what is the enthalpy change for the sublimation of iodine, represented below? I2(s) → I2(g)

21 kJ/molrxn

2 NH3(g) → 3 H2(g) + N2(g) ΔH°298 = 92 kJ/molrxn According to the information above, what is the standard enthalpy of formation, ΔH°f , for NH3(g) at 298 K ?

46 kJ/mol

Mg(s)+2HCl(aq)→MgCl2(aq)+H2(g) The chemical equation shown above represents the reaction between Mg(s) and HCl(aq). When 12.15g of Mg(s) is added to 500.0mL of 4.0MHCl(aq), 95kJ of heat is released. The experiment is repeated with 24.30g of Mg(s) and 500.0mL of 4.0MHCl(aq). Which of the following gives the correct value for the amount of heat released by the reaction?

95kJ