We need help on a Gen Chem 1 Calorimetry and Enthalpy lab and the TA for the cla

Question

We need help on a Gen Chem 1 Calorimetry and Enthalpy lab and the TA for the class wasn't much help at all.

1) Did the reaction absorb or release heat. Using the value of q you calculated, calculate del H of the reaction in kJ/mol of reactant. (start by calculation q for the reaction; don't forget the role of the calorimeter.) (our answer is -1.8kJ, but we know this must be incorrect since the TA got approx -51 kJ and then wouldn't show us what we did wrong.)

2)Write a balanced thermochemical equation for this reaction, including the value of del H

Reactant 1 (NaOH)
mass: 52.00g
volume: 50.0mL.
moles: 1.3 mol

Reactant 2 (HCl; density=1.017g/mL)
mass: 50.85g
volume: 50.00mL
moles: 1.4 mol

Solution:
mass: 102.85g
volume: 100 mL
Tinitial: 24.1C
Tfinal: 29.0C
delT: 4.9C
c for Sol: 3.97 J/g*C
q= 2000J (calculated using q=mc(del)T

Explanation / Answer

In this neutralization reaction heat is released as sign of q is -ve.

The only mistake you are doing is : you are not considering the heat absorbed by the calorimeter. To do that you have to calculate the calorimeter constant (this value will be mentioned in you lab manual/ procedure). Multiply this number with the temperature difference to get the amount of heat absorbed by the calorimeter.

Total amount of heat will come up to -51kJ.

Now you are using 1.3 mol NaOH so, to calculate delta H value

delta H = -51kJ/1.3 mol = -39.23kJ/mol

Between NaOH and HCL , NaOH is the limitinf agent. As its amount is less. So, you have to consider moles of naOH for enthalpy calculation . not moles of HCl which is present in excess.

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