How to measure the amount of hydrogen gas by the amount of salt produce in the reaction of HCL and Mg in an experiment.

Question

i am doing an experiment about the percent yeild of hydrigen gas from a solution of magnesium and hydrochloric acid but i need to find the amount of hydrogen produced but not sure how to do it. Was going to do it using volume by a eduiometer tube but dont have access to one. so what other options can i do in the experiment to measure hydrogen gas. Can i find the proportion of salt produced to hydrogen gas and use that to calculate amount of gas produced.

Answer 1

You could do the salt produced to calculate gas produced, but not gas collected (you may not collect all of the gas, as some may escape). Also, the salt produced will be MgCl₂ which is soluble so it will be difficult to determine the amount produced. Mg(s) + 2HCl(aq) ==> MgCl₂(aq) + H₂(g)

So, how can you do this without a eudiometer? You can either make your own (see below), or use a different method (collect the gas into a balloon and determine volume of the balloon).

To make your own eudiometer:

Fill a graduated cylinder with water and place a rubber or metal plate over the top.

Place some water into a beaker and invert the graduated cylinder and transfer to the beaker

Slide a tube into the opening of the cylinder and connect the other end to a stopper that will fit tightly into the reaction vessel. As soon as you mix the HCl and Mg, stopper the vessel and the gas should be collected into the graduated cylinder and will displace the water. At the end, you will be able to read the volume of gas collected.