Question

20. The chemical equation for the reaction between hydrochloric acid and potassium hydroxide is HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)

When 25 mL of 1.0 M HCl (36.5 g/mol) is mixed with 25 mL of 1.0 M NaOH (40 g/mol), the temperature change of the mixture is 6.9 oC. The density of the mixture is 1.00 g/mL and the specific heat of the solution is 4.18 J/ g oC. What is the enthalpy change for this reaction?

Answer 1

HCl(aq) + NaOH(aq) ----------->NaCl(aq) + H2O(l)

no of moles of HCl   = molarity *volume in L

                                 = 1*0.025 = 0.025 moles

no of moles of NaOH   = molarity *volume in L

                                     = 1*0.025 = 0.025 moles

Total volume of solution        = 25 +25 = 50ml

mass of solution                  = volume * density

                                             = 50*1 = 50g

T   = 6.9⁰C

q   = mcT

       = 50*4.18*6.9

         = 1442J

H   = -1442J

            = -1442J/0.025mole

   = -57680J/mole

                  = -57.68KJ/mole >>>>answer

the enthalpy change for this reaction   = -57.68KJ/mole >>>>answer