Question

Please answer and provide a step-by-step explanation on how you got the correct answer. (my answer was incorrect). Thank you!

13. Zinc metal reacts with hydrochloric acid according to the following balanced equation: Zn (s) + 2 HCl (aq) → ZnCl2 (aq) H2 (g) When 0.103 g of Zn (s) is combined with enough HCI to make 50.0 mL of solution TOTAL, in a coffee cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 22.5 °C to 23.7°C. Find ΔΗο for this reaction in kl per mol of Zn (s). Use 1.0 g/mL for the density of the solution and 4.184 J/gC as the specific heat capacity.

Answer 1

Ans :

Heat absorbed by the solution = mass x specific heat x change in temperature

now density = 1.0 g/mL , so the mass of 50 mL of solution will be 50 g

putting all the values :

= 50 x 4.184 x (23.7 - 22.5)

= 251.04 J

= 0.25104 KJ

molar mass of Zn = 65.38 g/mol

mol Zn = given mass / molar mass

= 0.103 g / 65.38 g/mol

= 0.00158 mol

$\Delta_{r}H^{o}$ = heat released / mol

= 0.25104 KJ / 0.00158 mol

= 159 KJ/mol