1.
CHEMISTRY 1 EXAMINATIONS -NOV 2017 PERIODIC TABLE OF THE ELEMENTS 10
A 100.0 mlL. sample of 0.300 M NaOH at 25 °C is mixed with a 100 ml solutionrks of 0.300
M HNOs solution at the same temperature in a calorimeter. The temperature of the resulting
solution is 27 C. What is the enthalpy of the reaction tag) THE REMAINDER OF THIS PAGE
IS FOR ROUGH WORKING ONLY.
Solution
Total volume of the reaction mixture = 200 mL
since, density of the solution is 1.00 g/mL, mass of the reaction mixture = 200 g
Specific heat of the reaction mixture is equal to the specific heat of the water = 4.184 J/g. 0
C
temperature change during the reaction = dT = 27 - 25 = 2 0 C
Heat of the reaction ( q ) = m x S x dT = 200 x 4.184 x 2 = 1673.6 J = 1.674 kJ
moles of the acid = moles of the base = 0.100 L x 0.300 mol/L = 0.03 mol
Now, Enthalpy of the reaction dH rxn = - q / n
=> dH rxn = - 1.674 kJ / 0.03 mol
=> dH rxn = -55.8 kJ/mol <<<<<---------(ANSWER)