Question

Consider the reaction between sulfuric acid and sodium hydroxide:

H₂SO₄(aq) + 2 NaOH(aq) → Na₂SO₄(aq) + 2 H₂O(l)                  ΔH_rxn = -111 kJ

125 mL of 0.200 M H₂SO₄(aq) and 125 mL of 0.200 M NaOH(aq) is mixed in a coffee cup calorimeter. Calculate q_rxn. The reaction goes to completion.

Answer 1

Answer

q_rxn = -1.39 kJ

Explanation

H2SO4(aq) + 2NaOH(aq) --------> Na2SO4(aq) + 2H2O(l) ∆H_rxn = - 111kJ

Stoichiometrically, 1mole of H2SO4 react with 2moles of NaOH to give 2moles of H2O

Given moles of H2SO4 = (0.200mol/1000ml) × 125ml = 0.0250mol

Given moles of NaOH = ( 0.200mol/1000ml) × 125ml = 0.0250mol

0.0250moles of NaOH react with 0.0125moles of H2SO4 to 0.0250moles of H2O

For the formation of 2moles of H2O 111kJ moles of heat is relesaed

Therefore ,

q_rxn = (-111kJ/2mol ) × 0.0250mol = -1.39kJ