Answer: The enthalpy change of the reaction is 49305.02 J/mol
Explanation:
To calculate mass of a substance, we use the equation:
\(\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}\)
We are given:
Density of solution = 1.00 g/mL
Volume of solution = (70.0 + 70.0) mL = 140.0 mL
Putting values in above equation, we get:
\(1g/mL=\frac{\text{Mass of solution}}{140.0mL}\\\\\text{Mass of solution}=(1g/mL\times 140.0mL)=140.0g\)
- To calculate the heat absorbed, we use the equation:
\(q=mc\Delta T\)
where,
q = heat absorbed
m = mass of solution = 140.0 g
c = specific heat capacity of water = 4.184 J/g.°C
\(\Delta T\) = change in temperature = \([24.25-23.16]^oC=1.09^oC\)
Putting values in above equation, we get:
\(q=140.0g\times 4.184J/g.^oC\times 1.09^oC\\\\q=638.5J\)
- To calculate the number of moles for given molarity, we use the equation:
\(\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (in mL)}}\)
Molarity of HCl solution = 0.185 M
Volume of solution = 70.0 mL
Putting values in above equation, we get:
\(0.185=\frac{\text{Moles of HCl}\times 1000}{70.0}\\\\\text{Moles of HCl}=\frac{0.185\times 70.0}{1000}=0.01295mol\)
- To calculate the enthalpy change of the reaction, we use the equation:
\(\Delta H_{rxn}=\frac{q}{n}\)
where,
\(q\) = amount of heat absorbed = 638.5 J
n = number of moles = 0.01295 moles
\(\Delta H_{rxn}\) = enthalpy change of the reaction
Putting values in above equation, we get:
\(\Delta H_{rxn}=\frac{638.5J}{0.01295mol}=49305.02J/mol\)
Hence, the enthalpy change of the reaction is 49305.02 J/mol
