**Review**

While working these problems, you may wish to review the section on coffee cup and bomb calorimetry and the laws of thermochemistry.

**Problem**

The following acid-base reaction is performed in a coffee cup calorimeter:

H^{+}(aq) + OH^{-}(aq) → H_{2}O(l)

The temperature of 110 g of water rises from 25.0°C to 26.2°C when 0.10 mol of H^{+} is reacted with 0.10 mol of OH^{-}.

- Calculate q
_{water} - Calculate ΔH for the reaction
- Calculate ΔH if 1.00 mol OH
^{-}reacts with 1.00 mol H^{+}

**Solution**

- Use this equation:
q = (specific heat) x m x Δt

where q is heat flow, m is mass in grams, and Δt is the temperature change. Plugging in the values given in the problem:

q

_{water}= 4.18 (J / g·°C;) x 110 g x (26.6°C - 25.0°C)q

_{water}= 550 J - ΔH = -(q
_{water}) = - 550 J - We know that when 0.010 mol of H
^{+}or OH^{-}reacts, ΔH is - 550 J:0.010 mol H

^{+}~ -550 JTherefore, for 1.00 mol of H

^{+}(or OH^{-}):ΔH = 1.00 mol H

^{+}x (-550 J / 0.010 mol H^{+})ΔH = -5.5 x 10

^{4}JΔH = -55 kJ

**Answer**

- 550 J (be sure to have 2 significant figures)
- -550 J
- -55 kJ

Would you like an example for bomb calorimetry? Then continue on to the second worked calorimetry problem > Next Page