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Chem Question!!!

Hi! I'm so confused please help me

I was given this question in my mock but I still don't really understand it:

0.72 g of magnesium is added to 100 cm of hydrochloric acid.

The hydrochloric acid is in excess.

Calculate the concentration of the magnesium chloride (MCl2) solution produced in g/dm'.

Relative atomic mass (A): Mg = 24

Relative formula mass (M): MgCl = 95

Wouldnt I just do mass of solute ÷ volume of solvent in dm3? so 0.72 ÷ 0.1? but then why have they given me the relative atomic and formula mass?

PLEASE HELP!!

Reply 1

Z_K

I’m guessing for this you would find the moles of MgCl₂by finding the moles of Mg first and using 1:1 ratio from the equation below. And from there find the mass of MgCl₂ and divide by the volume to get the concentration in g dm^-3.

Mg + 2HCl —> MgCl₂ + H₂

Hope this helps, I attached my working out. Let me know if you need any more help :smile: