1. Lab Report Tutorial
Mrs.Warren
Science

2. Parts of a Lab Report and Point Structure
Introduction – 5 points
Materials and Methods – 10 points
Results – 25 points
Discussion – 50 points
Conclusion – 5 points
Format – 5 points
_________________________________________
Total – 100 points

3. Introduction – 5 points One paragraph 1st sentence: purpose of the lab
2nd sentence: hypothesis (what you predicted would happen in the lab and why; if__ then__ because__ format)
Body of the paragraph – Background information:
Explain the concepts of the lab that someone would need to know in order to understand your lab

4. Introduction – 5 points Background information for BSV lab:
What was the reaction equation in symbols and words?
What are the reactants? What are the products?
What is a chemical change?
How can you tell a change occurs? (Work in endo- and exothermic here)
What is a closed system? What is an open system? Why is it important to know for this lab?
What is the Law of Conservation of Matter? Why is it important to this lab?

5. Materials and Methods Section – 10 pts
2 paragraphs (minimum)
Paragraph 1 – Materials:
Identify materials used
Describe lab setup/apparatus
Identify important safety precautions
Paragraph 2+ – Methods:
Step-by-step detailed procedure

6. Materials and Methods Section – 10 pts
Language is very important!
Procedure in your lab packet is written in COMMAND FORM
Change the language to:
PAST TENSE (because it already happened)
PASSIVE VOICE (objective tone)

7. Materials and Methods Section – 10 pts
EXAMPLE: From your procedure in your lab packet: Measure the bag apparatus using the triple beam balance. In your lab report: The bag apparatus was measured using the triple beam balance.

8. Results Section – 25 points
Includes two parts:
Data table (s) – quantitative observations (record measurements accurately!)
Observations – A detailed paragraph (if there are observations to report)
DO NOT EXPLAIN in the results section. EVER. Just state what happened, NOT why.

9. Discussion Section – 50 points
2 Paragraphs
1st Paragraph – Analysis of Results:
Sentence 1 = Hypothesis (focuses your paragraph)
Sentence 2 = The hypothesis was/was not supported.
Body of the Paragraph = Evidence
For each claim in the “if” and “then” parts of your hypothesis, identify and explain at least one piece of evidence to support it or show that it did not happen in the lab.
The number of pieces of evidence depends on the lab.

10. How to use your hypothesis to identify what to analyze with evidence:
If baking soda and vinegar react in a closed system, then the mass will stay the same because the Law of Conservation of Mass states that the mass of the reactants and products should be equal.

11. How to use your hypothesis to identify what to analyze with evidence:
For each part underlined, identify at least one piece of evidence to show that the claim happened or did not happen.

12. How to use your hypothesis to identify what to analyze with evidence:
baking soda and vinegar react:
Evidence comes from your observations
Which observations?

13. baking soda and vinegar react:
Bag felt cold – endothermic reaction (absorbed heat)
Fizzing sound – production of a gas (CO2)
Bag expanded – production of a gas (CO2)
Odor changed – vinegar smell went away and was replaced by a milder smell

14. How to use your hypothesis to identify what to analyze with evidence:
closed system:
Evidence may come from observations or data
mass will stay the same
Evidence comes from data

15. How to use your hypothesis to identify what to analyze with evidence:
You may write about these together or separately
closed system:
Evidence may come from observations or data
mass will stay the same
Evidence comes from data

16. closed system: Did your bag pop? Did it stay sealed?
Did it inflate and then deflate?
Did you puncture the bag with the paperclips?
Did the mass stay the same or did it change?
ALL OF THESE CAN BE EVIDENCE FOR WHETHER THE SYSTEM STAYED CLOSED OR OPEN. NOT ALL WILL PERTAIN TO YOUR LAB.

17. Mass stayed the same: LOOK AT YOUR DATA!!
Compare mass of bag apparatus before the reaction and after the reaction
Did the mass stay the same or change? Why?

18. Discussion Continued…
2nd Paragraph – Sources of Error
Identify any place where error was introduced into the lab
Errors include a failure in the apparatus or material(s) or human error in execution of lab procedures
Error should NOT be “The measurements should have been done more carefully.” This tells the reader that you didn’t care enough about the lab to be careful. If you made a mistake, include the SPECIFIC mistake you made.

19. Discussion Continued…
For each error, explain:
How the error affected the results
What could be done to eliminate the error next time

20. Conclusion – 5 points One paragraph: Sentence 1: Restate hypothesis
Sentence 2: State whether or not the hypothesis was supported
Sentence 3-5: Briefly summarize the evidence for sentence 2
Identify a way the lab could be improved OR an idea for future research

21. Chemical Change Lab

22. Chemical Reaction products reactants
HC2H3O NaHCO NaC2H3O H2O + CO2
 acetic acid sodium hydrogen carbonate sodium acetate water carbon dioxide (vinegar) (baking soda)
products
reactants

23. To measure the baking soda, you must first measure the mass of a cup
To measure the baking soda, you must first measure the mass of a cup. What is the purpose of the cup?
The purpose of the cup is just to serve as a container to hold the baking soda.

24. What are the units for each of the following measurements in this lab?
mass: __________
volume: _____________
time: ___________
Grams (g)
Milliliters (mL)
Seconds (s)

25. Hypothesize: You will measure the mass of the bag apparatus BEFORE the reaction and AFTER the reaction. Will the mass of the bag apparatus increase, decrease, or stay the same as the reaction occurs? Why?
If a chemical change between vinegar and baking soda is observed, then the mass of the bag apparatus will _______________ because _________________________

26. Measurements Mass of Beaker Total Mass of Cup & Baking Soda
Mass of Baking Soda
Volume of Vinegar
Mass of Apparatus BEFORE Chemical Change
Reaction Time
Mass of Apparatus AFTER Chemical Change

27. Did the mass of your bag apparatus increase, decrease, or stay the same during the reaction?
The mass of the bag should have stayed the same. Note: It does NOT matter if yours does not as long as you explained possible reasons in the next question.

28. What was supposed to happen to the mass during the reaction? Why?
The mass of the reactants should have EQUALLED the mass of the products. Conservation of Mass

29. How do you explain the change (or lack of change) in the mass of the apparatus during the chemical reaction?
If there was NO change, the system was a closed system, if there was a change, it was most likely because there was an opening in the bag which meant it was not a closed system.

30. During the chemical reaction, the temperature of the bag decreased.
During the reaction, you should have observed a temperature change in the bag. How did the temperature of the bag change?
During the chemical reaction, the temperature of the bag decreased.

31. Was this reaction endothermic or exothermic? Explain your answer.
The chemical reaction was an endothermic reaction because the temperature decreased.