A student adds 0.300 g of Zn(s) to 100.0 mL of 1.00 M HCl(aq) in a coffee-cup calorimeter
CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics
Problem
A student adds 0.300 g of Zn(s) to 100.0 mL of 1.00 M HCl(aq) in a coffee-cup calorimeter. The mass of the resulting solution is 100.0 g, and its temperature rises by 5.4 °C. Take the specific heat capacity of the solution to be 4.18 J g⁻¹ °C⁻¹ and the density to be 1.00 g mL⁻¹. Assuming Zn is the limiting reagent for the reaction
Zn(s) + 2 HCl(aq) → ZnCl₂(aq) + H₂(g),
what is the molar enthalpy change, ΔH, for the reaction expressed per mole of Zn that reacts? (Molar mass of Zn = 65.38 g mol⁻¹)
(a) +4.9×102kJ mol−1
(b) −4.9×101kJ mol−1
(c) −4.9×102kJ mol−1
(d) −2.5×102kJ mol−1