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wolverine [178]
3 years ago
13

When 0.103 g of Zn (s) is combined with enough HCl to make 50.0 mL of solution in a coffee cup calorimeter, all of the zinc reac

ts, raising the temperature of the solution from 22.5 degree C to 23.7 degree C. Find Delta H_rxn per mole of Zn. (Use 1.02 glmL for the density of the solution and 4.18 J/g degree C for the specific heat capacity.)
Zn (s) + 2 HCl (aq) rightarrow ZnCl_2 (aq) + H_2 (g)
Delta H_rxn/mol Zn = ____kJ/mol.
Chemistry
1 answer:
lbvjy [14]3 years ago
7 0

Answer:

\Delta H_{rxn}=162940 J/mol

Explanation:

To calculate the heat of reaction we need to determine:

  1. The heat produced
  2. The moles of Zn that reacted

<u>Moles of zinc (Zn)</u>

It says that the 0.103 g reacted completely, knowing that the Zn molecular weight is 65.4 g/mol:

n_{Zn}=\frac{0.103g}{65.4 g/mol}=1.57*10^{-3}mol

<u>Heat released by the reaction</u>

The solution goes from 22.5 °C to 23.7°C:

Q=Cp*\rho *V*(T_f - T_i)

Q=4.18 \frac{J}{g* ^{\circ}C}*1.02 g/mL*50mL*(23.7-22.5)^{\circ}C

Q=255.8 J

<u>Heat of reaction</u>

\Delta H_{rxn}=\frac{-Q}{n_{Zn}}

\Delta H_{rxn}=\frac{-255.8 J}{1.57*10^-3}}=162940 J/mol

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