Chapter 5 Lab Reports – Not a formal lab write up.
Please use the following to help guide you on what sections of the lab I want to see and evaluate. I will
be using the rubric (already given to you) to do the actual evaluation. Please organize your “report” so
that it will be easy for me to follow what you have done. Please include all pertinent equations using full
format and units. If it is not well organized, I may ask you to redo it. Please take care and do it well the
first time.
Investigation 5-A Determining the Enthalpy of a Neutralization Reaction
Section
Prediction
Analysis
/Conclusion
Application
Notes to help you.
This is the essentially the hypothesis section of a lab report. Give your prediction (endo
vs exo) and then using background knowledge “formulate an explanation of why you
can say it is exo or endothermic” Does anything about the reaction help you make your
prediction. Note you should only be able to explain qualitatively.
The analysis section Questions 1,2,3, and 5 of the conclusion section “walks you
through” the math/calculations that you will need to perform (see sample problem on
page 237) to get the heat of neutralization for this reaction. You can answer as one or
separate questions.
Question 4 of the analysis section is a two part question
1. Use your knowledge of solutions to explain what happens during a
neutralization reaction. Hint - Use equations in your answer. “
2. Was heat released or absorbed during the neutralization reaction? Explain your
answer. What observations did you make during the lab and what information
did you calculate to allow you to answer this question.
Enrichment – If you want you can add the following to your “write up”.
Suppose that you had added solid sodium hydroxide pellets to hydrochloric acid,
instead of adding hydrochloric acid to sodium hydroxide solution?
(a) Do you think you would have obtained a different enthalpy change? (b) Would the
enthalpy change have been higher or lower? Explain your reasoning.
Investigation 5-B Hess’s Law and the enthalpy of Combustion of Magnesium
Section
Question
Prediction
Analysis
/Conclusion
Notes to help you.
Essentially an Hess’s Law question (see sample problem 245) . Show how equations 2 3
and 4 can “add up” to give you equation 1.
This is the essentially the hypothesis section of a lab report. Give your prediction (endo
vs exo) and then using background knowledge “formulate an explanation of why you
can say it is exo or endothermic”. Does anything about the reaction help you make your
prediction?
The analysis sections part 1,2,3 “walks you through” the math/calculations that you will
need to perform (see sample problem on page 245) to get the heat of neutralization for
each reaction. You can answer as one or separate questions.
4(a) Your teacher (see below) will tell you the accepted value of ΔH of the combustion
of the magnesium. Based on the accepted value, calculate your percentage error.
(b) Suggest some sources of error in the investigation. In what ways could you improve
Conclusion
the procedure? For each step in the procedure identify (if possible) any
technical/technician, equipment or materials error that may account for the actual
value to be greater or less than the prediction value. Your decision on how you want to
present this (chart etc.)
For equation (2), the literature value for H° is -146 kJ/mol MgO.
For equation (3), the literature value for H° is -462 kJ/mol Mg.
7. Explain how you used Hess’s law of heat summation to determine the ΔH of the
combustion of magnesium. State the result you obtained for the thermochemical
equation that corresponds to chemical equation (1). Basically now that you have your
calculated H°s determine the H° for reaction 1 based on your values.