2 3 of 6 - SCH4U
Date: Name(s):
4. HCl is a corrosive colourless gas that dissolves readily in water.
Aqueous HCl reacts with NaOH to form water and NaCl. In a simple
calorimeter, a 100.00 mL sample of 0.415 mol/L HCl(aq) is mixed
with 50.00 mL of excess NaOH(aq). During the reaction, there is a
rise in temperature by 4.83 °C. Calculate the molar enthalpy change
(in kJ/mol) for the above reaction. SHOW ALL YOUR WORK.

The molar enthalpy change is 73.04 kJ/mol

Explanation:

moles of HCl=

As NaOH is in excess 0.0415 moles of HCl reacts with 0.0415 moles of NaOH.

volume of water = 100.0 ml + 50.0 ml = 150.0 ml

density of water = 1.0 g/ml

mass of water =

q = heat released

m = mass  = 150.0 g

c = specific heat =

= change in temperature =

Thus 0.0415 mol of HCl produces heat = 3031.3 J

1 mol of HCL produces heat =

Thus molar enthalpy change is 73.04 kJ/mol