Name:
Partners:
Lab Title: Heat of Reactions
Pre-lab Discussion
Define: Heat of reaction
Objective: Determine heats of reaction of three related exothermic reactions.
Equipment:
Materials:
Procedure:
Data Table:
Part A
Mass of 100mL of H2O
Mass of NaOH pellets
Temperature Original
Temperature Final
Delta T
Part B
50 mL NaOH + 50mL HCl
Temperature Original
Temperature Final
Delta T
Part C
Mass of 100mL of HCl
Mass of NaOH pellets
Temperature Original
Temperature Final
Delta T
100g
2g
100g
100g
2g
Calculations for part A
1. Find the number of joules absorbed by the water
q = mC∆T
2. Find the number of joules released per gram of NaOH
J/g of NaOH = joules(from 2)/2 g of NaOH
3. Find Delta H in kJ/mole NaOH
∆H = J/g NaOH x 40 g NaOH/ 1000
Part B
4. Find the number of joules produced by the reaction of NaOH and HCl:
q = mC∆T
5. Find ∆H in kJ/mole of NaOH
∆H = joules (from 4)/.5 mole
Convert into kilojoules
Part C
6. Find the number of joules absorbed by the HCl solution
q = mC∆T
7. Find the number if joules released per g of NaOH
J/g NaOH = joules(from 6)/2.00 g NaOH
8. Find ∆H in kj/mole NaOH:
∆H = J/g NaOH x 40 g/mole NaOH
Convert to kilojoules
Analysis questions
1. Write the ionic equations form the three reactions observed in this experiment.
2. Find the product of Part A and Part B. How does the value compare to the ∆H of part C?
3. Calculate the percent error from question 2.
4.
What are some sources of error in this experiment?
5.
How does this experiment illustrate the law of conservation of energy?