Question

A 5.00 x 10^2 mL sample of 2.00 M HCl soloution is treated with 4.47g of magnesium metal.

A) show the balanced chemical equation for the reaction that occurs

B) calculate the concentration of the acid solution after all metal has reacted. Assume volume is a constant.

Answer 1

a)

Mg(s) + 2HCl(aq) --> MgCl2(aq) + 2H+(aq)

b)

concentration of acid after reaction

M = mol/V

mol left = Hfinal - H initial

V = 500 ml or 0.5 L

mol of HCl initial = M*V = (0.5) * 2 = 1 M

change Mg to mol

mol = mass/MW = 4.47/24.3 = 0.18395 mol

V = 5*10^2 = 500 ml = 0.5 L

then M = 0.18395 /(5*10^-1 ) = 0.3679

ratio is

1:2 therefore

0.3679 need 0.3679*2 = 0.7358 M of HCl which we do not have so HCl is limiting

final concnetration of H+ must be = to that of initial

[H+] = 2M