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 `1gm-mL^(-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

`Mm` of `HCl=50xx1.0=50,`
`Mm of NaOH=50xx1.0=50`
Heat changes during mixing `=m.x.DeltaT`
`5- mM ` of `HCl` and `50mM` of `NaOH=(100xx1)xx4.18xx6.5=2717J=2.72kJ`
Further, on mixing `50mM` of `HCl` and `50mM` of `NaOH` produces heat `=2.72kJ`
`:. 1000mM` of `KCl(` or `1000Meq.)` and `1000mM` of `NaOH` produces heat
`=(2.72xx1000)/(50)=54.4kJ`
`( :'` acid and bases are monobasic and monoacidic, respectively `).`