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# Lab Reports

Everything You Didn’t Want to Know!. Lab Reports. Components of a Lab Report. Title Purpose Procedure Safety Data Calculations Conclusion. How to Write a Lab Report. Title: Placed at top center of page one Descriptive and appropriate. Density of Solids

## Lab Reports

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### Presentation Transcript

1. Everything You Didn’t Want to Know! Lab Reports

2. Components of a Lab Report • Title • Purpose • Procedure • Safety • Data • Calculations • Conclusion

3. How to Write a Lab Report • Title: • Placed at top center of page one • Descriptive and appropriate Density of Solids Purpose: TPOTLIT investigate the density of various solids. Procedure: The relationship between the mass of an object and its volume is called density. The mass and volume of various cubed shaped substances were determined. The density was calculated by dividing the mass of the cube by its volume. Safety: Beware of glass cutsWipe up any spills immediately • Purpose: • One sentence telling why the lab was performed • Procedure: • A paragraph summarizing how the lab was performed. • Include key concept(s), formula, and/or • physics equation • Safety: • Specify safety rules

4. Data Includes both qualitative and quantitative observations Quantitative data should be arranged in a data table format Always use units of measurements Always use Significant Figures Data: Cylinder Mass (g) Volume (ml) Density (g/ml) aluminum 5.40 1.8 3.0 copper 18.00 2.0 9.0brass 15.60 2.0 7.8lead 22.80 2.0 11.4iron 15.80 2.0 7.9

5. * Show a sample of how the calculation was performed. * Usually use first data set * Write Formula * Sub in #s with units * Answer with units rounded off to the correct # of sig figs Calculations: D = M V D = 5.40 g 2.0 ml D = 2.7 g/ml Calculations

6. It is the most important part of the lab report. It is where you tell me what you learned from the lab. It always relates back to the purpose of the lab. It should include a discussion of sources of error. It is written in the third person. It could suggest further investigations. Conclusion: Different materials seem to have different densities. The five cubes have the same volume but their masses are different and consequently they have different densities. Aluminum, copper and lead have densities that are very different from each other. Of these three aluminum has the smallest density and lead has the largest density. Brass and iron have similar densities. The density of the copper, brass, lead and iron cubes are exactly the same as the values reported in the CRC handbook of chemistry and physics. The density of aluminum should have been 2.7 g/ml. A source of error in this experiment is the measurement of the volume of the cubes using the water displacement method. When the cubes were dropped into the graduated cylinder water tended to splash out. This made the volume of the cube smaller than it really was and the density of the cube larger than the actual value. This would account for the measured density of aluminum being 3.0 g/ml. Another experiment might be to measure the density of aluminum cubes that have different volumes. If the densities of these cubes were the same, density would be a characteristic property. A characteristic property allows one to distinguish substances regardless of the size of sample tested. Conclusion

7. Conclusion Conclusion: Different materials seem to have different densities. The five cubes have the same volume but their masses are different and consequently they have different densities. Aluminum, copper and lead have densities that are very different from each other. Of these three aluminum has the smallest density and lead has the largest density. Brass and iron have similar densities. The density of the copper, brass, lead and iron cubes are exactly the same as the values reported in the CRC handbook of Chemistry and Physics. The density of aluminum should have been 2.7 g/ml. A source of error in this experiment is the measurement of the volume of the cubes using the water displacement method. When the cubes were dropped into the graduated cylinder water tended to splash out. This made the volume of the cube smaller than it really was and the density of the cube larger than the actual value. This would account for the measured density of aluminum being 3.0 g/ml. Another experiment might be to measure the density of aluminum cubes that have different volumes. If the densities of these cubes were the same, density would be a characteristic property. A characteristic property allows one to distinguish substances regardless of the size of the sample tested.