Question

When 1.04E-1 g of Zn(s) combines with 5.79E+1 mL of HCl(aq) in a coffee cup calorimeter, all of the zinc reacts, which increases the temperature of the HCl solution from 2.31E+1 °C to 2.49E+1 °C: Zn(s) + 2HCl(aq) → ZnCl2(aq) + H₂(g) Calculate the enthalpy change of the reaction ΔH_rxn in J/mol. (Assume the volume of the solution doesn't change, density of the solution is 1.00 g/mL, and the specific heat capacity of the solution is 4.184 J/g°C.)

Answer 1

To calculate the enthalpy change of the reaction (ΔH_rxn) in J/mol, we need to use the formula: ΔH_rxn = q / n. In the given problem, we are given the heat produced (3.14 kJ) and the mass of zinc (1.34 g). We need to convert the mass of zinc to moles using its molar mass.

Step-by-step explanation:

To calculate the enthalpy change of the reaction (ΔH_rxn) in J/mol, we need to use the formula:

ΔH_rxn = q / n

Where:

• q is the heat produced or absorbed by the reaction, in joules
• n is the number of moles of zinc reacting

In the given problem, we are given the heat produced (3.14 kJ = 3.14 x 10^3 J) and the mass of zinc (1.34 g). We need to convert the mass of zinc to moles using its molar mass.

The molar mass of zinc (Zn) is 65.38 g/mol, so:

moles of Zn = mass of Zn / molar mass of Zn

moles of Zn = 1.34 g / 65.38 g/mol = 0.0205 mol

Now that we have the value of moles of zinc (n), we can calculate ΔH_rxn:

ΔH_rxn = q / n = (3.14 x 10^3 J) / (0.0205 mol)

ΔH_rxn = 153,170 J/mol