Question

The addition of hydrochloric acid to a silver nitrate solution precipitates silver chloride according to the following reaction:

AgNO3(aq) + HCl(aq) → AgCl(s) + HNO3(aq)

When 50.0 mL of 0.100 mol L−1 AgNO3 is combined with 50.0 mL of 0.100 mol L−1 HCl in a coffee-cup calorimeter, the temperature changes from 23.40 °C to 24.21 °C. Calculate ΔrH for the reaction as written. Use 1.00 g mL−1 as the density of the solution and C = 4.184 J g−1 °C−1 as the specific heat capacity.

Answer 1

Solution:

q = mc (T₂ - T₁)

q = 100g (4.184 $(\frac{J}{gC})$) (24.21 - 23.40)C

q = 301 J

Moles AgCl formed = 0.05 L * 0.100 $(\frac{mole}{J})$ = $5*10^{-3}mole$

$\Delta H_{reaction}$ = $\dfrac{-301J}{5*10^{-3}mole}=6*10^{4}(\frac{J}{mole})=6\;(\frac{kJ}{mole})$