When 0.100 L of 1.00 mol L−1 HCl(aq) is mixed with 0.100 L of 1.00 mol L−1 NaOH, the temperature of the solution rises by 8.5 oC. Assuming no heat loss to the container or the surroundings, what is the heat of reaction for the following reaction? (You may also assume that, for these aqueous solutions, the density is about 1.0 g mL−1 and the heat capacity is about 4.2 J g−1 oC−1.)

Question

When 0.100 L of 1.00 mol L−1 HCl(aq) is mixed with 0.100 L of 1.00 mol L−1 NaOH, the temperature of the solution rises by 8.5 oC. Assuming no heat loss to the container or the surroundings, what is the heat of reaction for the following reaction? (You may also assume that, for these aqueous solutions, the density is about 1.0 g mL−1 and the heat capacity is about 4.2 J g−1 oC−1.)
H+(aq) + OH−(aq) → H2O(l)
A −4.8 kJ mol−1
B −7.1 kJ mol−1
C −18 kJ mol−1
D −36 kJ mol−1
*E −71 kJ mol

DrBob222 · Answer

I get 71 kJ/mol q = mass H2O x specific H2O x delta T q = 200 g x 4.2 J/g*c x 8.5 = 7140 J. mols = M x L = 1 M x 0.1 L = 0.1 -7140 J/0.1 mol = 71400 J/mol = 71.4 kJ/mol