Directions
How can we write a laboratory report?
How can we write a laboratory report?
Scientists do more than perform experiments - they communicate their findings clearly and accurately.
A laboratory report allows you to explain what you investigated, what evidence you collected, and what conclusions you reached based on that evidence.
A strong laboratory report demonstrates your ability to think like a scientist by making observations, analyzing data, and supporting conclusions with evidence.
Your laboratory report must include the following sections:
The title should clearly describe the investigation.
The Effect of Temperature on the Solubility of Potassium Nitrate
The aim states the purpose of the investigation.
What am I trying to determine?
What scientific concept am I investigating?
How does temperature affect the solubility of potassium nitrate in water?
A hypothesis is an educated prediction based on scientific reasoning.
If ____________, then ____________ because ____________.
If the temperature of water increases, then more potassium nitrate will dissolve because particles move faster and have more energy to interact.
✔ Make a prediction before conducting the experiment.
✔ Use scientific reasoning.
✔ Your hypothesis does NOT have to be correct.
List all equipment and chemicals used during the investigation.
100 mL beaker
Graduated cylinder
Thermometer
Potassium nitrate
Distilled water
Hot plate
Write the steps of the investigation in numbered order.
Use complete sentences.
Number each step.
Write clearly enough that another student could repeat the experiment.
Measure 50 mL of water using a graduated cylinder.
Pour the water into a beaker.
Heat the water to 40°C.
Add potassium nitrate while stirring.
Record all measurements and observations.
Data tables
Measurements with units
Qualitative observations
Quantitative observations
Describe what you see.
Examples:
Solution turned blue.
Gas bubbles formed.
White precipitate appeared.
Include numbers and units.
Examples:
Temperature = 25°C
Mass = 12.5 g
Volume = 50.0 mL
✔ Record data exactly as observed.
✔ Never change data to match expected results.
Show all work for calculations.
Formula used
Substitution
Mathematical work
Final answer with units
Density = Mass ÷ Volume
Density = 12.5 g ÷ 5.0 mL
Density = 2.5 g/mL
✔ Show every step.
✔ Include units throughout calculations.
✔ Circle or box final answers.
Graphs help scientists identify patterns and relationships.
✔ Title
✔ X-axis labeled
✔ Y-axis labeled
✔ Units included
✔ Appropriate scale
✔ Best-fit line if required
Effect of Temperature on Solubility
Answer all questions using complete sentences.
Scientific vocabulary
Evidence from the investigation
Explanations based on chemistry concepts
The solubility increased as temperature increased. At 20°C, 30 g dissolved, while at 60°C, 75 g dissolved.
This occurred because particles moved faster at higher temperatures.
Your conclusion should be written using Claim-Evidence-Reasoning (CER).
Answer the Aim.
Use specific data from your investigation.
Explain WHY the evidence supports your claim using scientific principles.
Claim
Temperature affects the solubility of potassium nitrate.
Evidence
At 20°C, only 30 g dissolved in 100 g of water. At 60°C, 75 g dissolved.
Reasoning
As temperature increases, particles gain kinetic energy and collide more frequently. This increases the ability of the solvent to dissolve the solute.
Identify factors that may have affected your results.
Measurement errors
Heat loss
Equipment limitations
Human error
Some heat was lost to the surrounding environment while transferring the solution, which may have affected the measured temperature.
Describe how the investigation could be improved.
Use more precise measuring equipment.
Increase the number of trials.
Use digital sensors for data collection.
Before submitting, make sure you have:
☐ Title
☐ Aim
☐ Hypothesis
☐ Materials
☐ Procedure
☐ Data Table
☐ Observations
☐ Calculations
☐ Graph (if required)
☐ Analysis Questions
☐ CER Conclusion
☐ Sources of Error
☐ Improvements
☐ Complete Sentences
☐ Scientific Vocabulary
☐ Proper Units
☐ Neat and Organized Work
An excellent laboratory report:
✔ Is complete and organized
✔ Uses scientific vocabulary correctly
✔ Includes accurate data and calculations
✔ Supports conclusions with evidence
✔ Explains results using chemistry concepts
✔ Demonstrates clear scientific thinking
Remember: The goal is not simply to get the "right answer." The goal is to think, communicate, and analyze like a scientist.