Lab Report Rate of Effusion of a Gas

[adletaY]

Hello all. I'm planning a Chem Lab for Acids and Bases where I'm measuring the rate of reaction between HCl and Mg by measuring the rate of effusion of hydrogen gas. However, I'm not sure if it is feasible to measure the rate of effusion of a gas with a gas collection tube. I was wondering if this is in fact a good idea, or if I should change my experiment, because we have no other equipment available to measure the volume of gas given off.

[Keel]

Hello all. I'm planning a Chem Lab for Acids and Bases where I'm measuring the rate of reaction between HCl and Mg by measuring the rate of effusion of hydrogen gas. However, I'm not sure if it is feasible to measure the rate of effusion of a gas with a gas collection tube. I was wondering if this is in fact a good idea, or if I should change my experiment, because we have no other equipment available to measure the volume of gas given off.

Hi,

That is perfectly fine. There is simply one catch to the experiment. By 'rate of reaction' you should be aiming to find out the initial rate of reaction. Why? Say you waited one minute and read the volume of gas collected then, you would be working out the average rate of reaction for that one minute and that is not what you want. If you didn't get that, lets say you let the reaction go to completion then take the reading, all you readings would be the same simply because they are limited by the limiting reagent, all the experiments would give out the same volume of gas.

So what to do? Limit your gas reading time to something small (e.g. 10 seconds after the start) this can represent the inital rate of reaction closely and you will see a more definite increase in the rate when you increase the concentration of either reactant.