When a student mixed `50mL` of `1M HCI` and `150mL` of `1M NaOH` in a coffee cup calorimeter, the temperature of the resultant solution increases from `21^(@)C` to `27.5^(@)C`. Assuming that the calorimeter absorbs only a negligible quantity of heat, that the total volume of solution is `100mL`, its density `1gmL^(-1)` and that its specific heat is `4.18 J g^(-1)`. calculate:
a. The heat change during mixing.
b. The enthalpy change for the reaction
`HCI(aq) +NaOH(aq) rarr NaCI(aq) +H_(2)O(aq)`

Explanation

To solve the problem, we will calculate the heat change during the mixing of HCl and NaOH, and then use that to find the enthalpy change for the reaction.

### Step 1: Calculate the heat change (q) during mixing.

The formula to calculate the heat change is given by:
\[ q = m \cdot c \cdot \Delta T \]
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