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ΔH=-q

ΔH R1=-1.875kJ

ΔH R2=-4.678kJ

ΔH R3=-2.865kJ

 

mol R1=2.00/(22.99+16.00+1.008)=0.05 mol

mol R2=2.00/(22.99+16.00+1.008)=0.05 mol

mol R3=1.0*50.1000=0.05 mol

 

ΔH/mol R1=-1.875/0.05=-37.5 kJ/mol

ΔH/mol R2=-4.678/0.05=-93.6 kJ/mol

ΔH/mol R3=-2.865/0.05=-57.3 kJ/mol

 

-ΔH1  ΔH2  ΔH3

-37.5+-57.3=-94.8 kJ/mol

37.5+-93.6=-56.1 kJ/mol

|-94.8+93.6| / |-93.6| *100=1.28% error

Conclusion:

The purpose of the lab was to practice applying Hess's Law and verifying that the heat of a reaction is equal to the sum of the other reactions. We achieved this by using a coffee cup calorimeter to combine NaOH with water and HCl and using a thermal probe to measure the initial and final temperature, which was used along with the mass or volume of NaOH, to find the heat released, which was used to find ΔH. We then used the mass of NaOH to find the ΔH/mol. We then added two reactions and compared them against the third to verify the data/calculations.