I'm not sure on how to set this equation up.

Question

Mixing 25.0 mL of 1.2 M HCl and 25.0 mL of 1.1 M NaOH were mixed. The temperature of the initial solution was 22.4 oC. Assuming a Heat of Neutralization of -55.8 KJ/mol, what would the final temperature be if the specific heat for this solution is 4.03 J/g oC?

Answer 1

Let’s begin with the balanced equation

HCl + NaOH ==> NaCl + H2O

moles HCl = 0.025L x 1.2 mol/L = 0.03 mol

moles NaOH = 0.025L x 1.1 mol/L = 0.0275 mol

NaOH is limiting so only 0.0275 moles are neutralized

Heat generated during neutralization = 0.0275 mols x 55.8 kJ/mole = 1.53 kJ = 1530 J

q = mCΔT

assuming density of 1 g/ml and a final volume of 25 ml + 25 ml = 50 ml = 50 g

1530 J = (50 g)(4.03 J/g^o)(ΔT)

ΔT = 7.59^o

Final temp = 23.4^o+ 7.6^o = 32.0^o