when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 Ā°c, the temperature increased to 22.1 Ā°c. the heat capacity of the calorimeter is 279 j/Ā°c.
the equation for the reaction is:
naoh + hcl ā nacl + hāo
moles of hcl = 0.0250 l hcl Ć
0.700
mol hcl
1 l hcl = 0.0175 mol hcl
volume of solution = (25.0 + 25.0) ml = 50.0 ml
mass of solution = 50.0 ml soln Ć
1.00
ml soln
= 50.0 g soln
Ī“t=t2-t1
= (22.1 ā 20.0) Ā°c = 2.1 Ā°c
the heats involved are
heat from neutralization + heat to warm solution + heat to warm calorimeter = 0
q1+q2+q3=0
nĪ“h+mcĪ“t+cĪ“t=0
0.0175 mol Ć
Ī“h
+ 50.0 g Ć 4.184 jĀ·gā»Ā¹Ā°cā»Ā¹ Ć 2.1 Ā°c + 279 jĀ°cā»Ā¹ Ć 2.1 Ā°c = 0
0.0175 mol Ć
Ī“h
+ 439.32 j + 585.9 j = 0
0.0175 mol Ć
Ī“h
= -1025.22 j
Ī“h=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol