Using a gas syringe

Question 1

what are the potential errors when using a gas syringe

Answer 1

1) gas escapes before bung inserted
2) syringe sticks
3) some gases (e.g carbon dioxide or sulphur dioxide) are
soluble in water so the true amount of gas is not measured.

Question 2

Method for using a gas syringe to calculate the Mr

Answer 2

1. Extract 0.20 cm3 of substance into a hypodermic syringe and then measure the mass of this syringe
2. using hand protection, remove a gas syringe from the oven and note the volume of air already in the barrel – about 5 cm3.
3. Inject the substance through the self-seal cap into the barrel. The plunger will move straight away.
4. Put the gas syringe back into the oven.
5. Measure the mass of the empty hypodermic syringe immediately.
6. After a few minutes measure the volume of the gas in the gas syringe, record the temperature of the oven
   shelf and the pressure of the room.