Question

<b>My objective is to find the molar mass of a gas.

Is this the correct balanced equation for magnesium ribbon reacting with hydrochloric acid to form hydrogen gas?</b>

2Mg (s) + 2HCL (l) ----> H2 (g) + 2MgCl (aq)

<b>Also, I'm required to find the mass of the magnesium ribbon in grams and the moles of the hydrogen gas collected.</b>

Is it correct to multiply the mass per meter (1.702 g/m) by the m of ribbon in order to get the mass?

then once i have the grams do i change it to moles of Mg? how do i get moles of h2? use the mole ratio of the equation?

Answer 1

No. Correct the formula for MgCl2 and then rebalance.

Yes, mass is m/l * length

Yes, then change that mass to moles. You get moles of H2 from the balanced equation coefficents and the moles of Mg.

I will be happy to critique your thinking.

Answer 2

Thanks, sir.

This is what I did, could you tell me if its correct?

given value 1.072 g/meter

1.072 g/m X .02 m [the magnesium ribbon was 2.0 cm] = 0.02144 gMg

Then to find the moles of H2:

0.02144 g mg ( 1 mol Mg/24.31 g Mg) (2 mol H2/1 mol Mg) = 1.76 X 10^ -3