Volume Lab Answer Key
Part A: Answers will vary; however, my students usually end up with an average of 20 drops per milliliter. The biggest problem I encounter is that students count the number of drops to 11 ml. They should fill the cylinder to 10 ml (meniscus is on the 10 ml mark) and count the number of drops it takes to reach 11 ml.
Part B: Answers will vary. My students usually end up with a volume of 5-6 ml for three marbles.
Part C: Students should end up with measurements of 6.5 cm, 3 cm, and 1.5 cm if they measure to the nearest centimeter (two decimal places). The answer would be 6.5 x 3 x 1.5 = 29.25 cm3.
Part D: Students should end up with final measurements of 10 ml in each test tube if they measured carefully for each step. I allow ±0.5 ml for error. The final colors should be A – red, B – orange, C yellow, D – blue, E – green, and F – purple.
TIP: When mixing the main colors, make all of them dark. It is a good idea to test the colors before the lab to make sure the final results are close to the colors listed above. The purple often ends up as a very dark purple. It does help to hold the test tubes up to a light to determine the final colors.
Safety Rules: After the lab, ask students if anyone has colored hands or papers and relate to lab safety rules. If the water samples were chemicals, colored hands or papers would indicate that the person came in contact with the “chemicals.”