Collecting Gas Overview

Hey!

Water displacement method

I learnt two different ways of collecting/measuring the volume of gas produced from reactions. One way is by the water displacement. In this method water is filled in a measuring cylinder which is clamped over a trough upside down. You have to make sure that the mouth of the measuring cylinder is still in the water so that no air can escape. Then gas is collected in the measuring cylinder through the delivery tube. This allows you to measure the volume of gas produced. 

Gas syringe method

The other way to measure the volume of gas is by using gas syringe. The syringe is connected by a tube to the flask that contains the gas. As the volume of gas increases the plunger moves out of the syringe, 

Allowing you to measure the volume of gas made. 

I prefer to collect gas using the gas syringe. This is because it is easier to use and read. It is also more accurate because when collecting gas by water displacement, more air is likely to escape resulting in obtaining anomalous results. Moreover the gas syringe is also more reliable than the water displacement method as air can escape from the measuring cylinder easily if taken out of the trough, where as in the gas syringe the plunge on the end of the syringe stops the gas from escaping or any gas in the air from entering. Furthermore, I find that the water displacement method is more fiddly and longer to carry out, compared to the gas syringe.

Let me know what you guys think...

Thanks :)