Question

A student needs to determine the volume occupied by a gas in a 125 mL flask using the experimental setup described in the procedure. The student measures the volume of the flask to be 157 mL to the top of the flask. The student measures the volume of the flask with a stopper in it to be 140 mL. The student performs the experiment by reacting the strip of magnesium with 5 mL of HCl solution. What is the volume of the flask occupied by the hydrogen gas?

Answer 1

see explanation...

Step-by-step explanation:

Given 125ml standard flask

Measured volume to top = 157ml

Measured volume with stopper = 140ml

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Based on the wording of the question, the volume of the flask is ...

= 157ml without stopper*, or

= 140ml with stopper.

If interest is in volume occupied by H₂(g) above 5ml of rxn solution ...

=> Volume without stopper* = 157ml - 5ml = 152ml above rxn solution

=> Volume with stopper = 140ml - 5ml = 135ml (Assuming stopper doesn't pop out of container). :-)

*Assuming gas fills available volume without escaping container.

Answer 2

Volume of flask without stopper=157 mL-5mL=152 mL

Volume of flask with stopper=140-5=135 mL