When using a gas collection apparatus in a lab to collect gases such as CO₂, certain assumptions are typically made to ensure the accuracy of the experiment. Based on your options, the following assumptions can be selected:
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The reaction begins after the test tube is capped, so CO₂ is not lost to the atmosphere - This assumes that once the apparatus is sealed, all the gas produced is contained and collected without any losses to the surrounding environment.
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The pressure and temperature of the room remain constant - This assumption is important because variations in pressure and temperature can affect the gas volume and the overall measurements.
The statement about percent recovery accounting for all the CO₂ lost during water displacement may not be a valid assumption without proper measurement, so it should not be selected. The choice indicating "We make no assumptions in this lab" is also not accurate, as there are always assumptions made when conducting experiments.
So, the answers to select are:
- The reaction begins after the test tube is capped, so CO₂ is not lost to the atmosphere
- The pressure and temperature of the room remain constant