[standard enthalpy formation]

remember to show work and explain.

1. use the equation below to determine the amount of energy released when 78.0g of h2s react with excess so2.

2. how many grams of 2agno3 are needed to react to produce 567kj of energy in the following reaction?

1. 65.1 kJ; 2. 558 g

Step-by-step explanation:

1.

M_r: 34.08

        2H₂S+ SO₂ ⟶ 3S + 2H₂O ; ΔH = -56.9 kJ

Treat the heat as if it were a product in the equation. Then use the molar ratio (56.9 kJ/2 mol H₂S) in the usual way.

Moles of H₂S = 78.0 g H₂S × (1 mol H₂S/34.08 g H₂S) = 2.289 mol H₂S

Amount of heat = 2.289 mol H₂S × (56.9 kJ/2 mol H₂S) = 65.1 kJ

The reaction releases 65.1 kJ of energy.

2.

M_r:   169.87

         2AgNO₃ + BaCl₂ ⟶ 2AgCl + Ba(NO₃)₂; ΔH = -345 kJ

Moles of AgNO₃ = 567 kJ × (2 mol AgNO₃/345 kJ = 3.287 mol AgNO₃

Mass of AgNO₃ = 3.287 mol AgNO₃ × (169.87 g AgNO₃/1 mol AgNO₃)

= 558 g AgNO₃

You need 558 g of AgNO₃.