Three measuring cylinders have scale divisions of 1 mL, 2 mL and 5 mL. Water density is supplied as 1.00 g/mL for this classroom comparison. Available equipment and procedure options: Pour each nominal dose into a tared cup on a 0.1 g balance; volume in mL equals water mass in g under the supplied density assumption. Design an investigation of how the cylinder scale-division size affects the difference between a nominal 15 mL dose and its mass-derived volume. Include a reasoned hypothesis, an appropriate range, controls, repeat measurements, a results table or graph, and one specific limitation and safety measure. Do not invent experimental results.

Question

Accepted Answer

Vary the cylinder scale-division size; measure the difference between a nominal 15 mL dose and its mass-derived volume. Predict The cylinder with finer divisions should usually allow a smaller spread around the target volume. Keep target volume, water temperature, operator and drain time constant, repeat each setting, and use the evidence to test the prediction. State a testable research question linking the cylinder scale-division size to the difference between a nominal 15 mL dose and its mass-derived volume, rather than asking vaguely which arrangement is best. A suitable prediction is: The cylinder with finer divisions should usually allow a smaller spread around the target volume. Justify that prediction scientifically: A meniscus can be located within a smaller absolute interval on a finer scale, although pouring technique also matters. This is a hypothesis to test, not a result that the experiment must produce. Use the available 1 mL, 2 mL and 5 mL divisions as the planned independent-variable settings. Measure the response using the supplied equipment: Pour each nominal dose into a tared cup on a 0.1 g balance; volume in mL equals water mass in g under the supplied density assumption. Record quantities with units before calculating any derived result. Keep target volume, water temperature, operator and drain time constant. This isolates the proposed cause; changing these conditions at the same time would allow competing explanations for any difference. Take at least three independent trials at each setting, resetting the apparatus each time. Tabulate the setting, individual responses and mean; plot the mean response against the changed quantity and show the range of repeated values. Evaluate this specific limitation: Water left on cylinder walls changes delivered volume; standardise draining rather than assuming the initial reading equals delivery. More repeats alone do not necessarily correct a biased method. Protect participants and equipment by this precaution: Use plastic cylinders and dry the balance area.

Choosing a cylinder for a small dose

What a complete response should do

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