Question

Check my answers please? 1. Which of the following is a correctly written thermochemical equation? NH4Cl NH4+ + Cl 2C8H18 + 25O2 16CO2 + 18H2O, H = 5,471 kJ/mol Fe (s) + O2 (g) Fe2O3 (s), H = 3,926 kJ -->C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (l), H = 2,220 kJ/mol 2. How does a phase change affect a thermochemical equation? It alters the moles of reactants. -->It can affect the (delta) H value. It alters the products. It affects the balance of the equation. 3. For the reaction CH4 (g) + 2O2 (g) CO2 (g) + 2H2O (l), H = 890 kJ, what will be the change in enthalpy when 3 moles of methane react in excess oxygen?
890 kJ

-->2.67 × 103 kJ

+890 kJ

+2.67 × 103 kJ

4. In which of the following thermochemical equations would the H be considered a heat of solution?

NH4Cl (s) NH4+ (aq) + Cl (aq), H = + 14.8 kJ/mol

2C8H18 (l) + 25O2 (g) 16CO2 (g) + 18H2O (l), H = 5,471 kJ/mol

-->4Fe (s) + 3O2 (g) 2Fe2O3 (s), H = 3,926 kJ

C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (l), H = 2,220 kJ/mol

5. For the following reaction at STP, how much heat will be required to produce 63 L of NO? (At STP, one mole of any gas occupies 22.4 L.)

N2 (g) + O2 (g) 2NO (g), H = 180.5 kJ

+63 kJ

+127 kJ

-->+254 kJ

+508 kJ

Answer 1

1. I think you chose the right answer, the equation has the states of the reactants and products. 2. I think you chose the right answer. 3. I think you also chose the right answer. Assuming that the Hrxn is written as kJ per mol CH4 4. Heat of solution is the enthalpy change associated with dissolving a solute in a solvent. I think the first choice is the right one. 5. I think you chose the right answer.