Answer:
The enthalpy change is -249.1 kJ/mole
Explanation:
<u>Step 1: </u>The balanced equation
Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g)
<u>Step 2: </u>Data given
mass of Zn = 0.121 grams
volume of the solution = 52.5 mL = 0.0525 L
Initial temperature = 21.8°C
Final temperature = 23.9 °C
Density of the solution = 1g/mL
Specific heat capacity = 4.18 J/ g°C
<u>Step 3</u>: Calculating mass of solution
mass = density * volume
mass = 1g/ mL * 52.5 mL = 52.5 grams
<u>Step 4: </u>Calculate heat transfer
Q = m*c*ΔT
with m = mass of the solution = 52.5 grams
with c= the specific heat capacity of the solution = 4.18 J/g °C
with ΔT = the change in temperature = final - initial temperature = 23.9 - 21.8 °C = 2.1 °C
Q = 52.5 grams * 4.18 J/g°C * 2.1 °C = 460.845 J
<u>Step 5:</u> Calculate number of moles of Zn
moles = mass of Zinc / Molar mass of Zinc
moles of Zinc = 0.121 grams / 65.38 g/mol = 0.00185 moles
<u>Step 6:</u> Calculate enthalpy change
ΔHrxn = heat / moles
ΔHrxn = 460.845 J / 0.00185 moles = 249105.4 J/mole = 249.1 kJ/mole
Since reaction is exothermic, ΔHrxn is negative.
ΔHrxn = -249.1 kJ/mole
