If 2.00 g of mg reacts completely with 50.0 ml of hcl solution, what is the molarity of the hcl solution? mg (s) + 2hcl (aq) → mgcl2 (aq) + h2 (g)

The molarity of HCl is calculated as below

find the moles of mg used

moles = mass / molar mass

= 2.00g/24 g/mol=0.083 moles

write the reacting equation

Mg (s) + 2HCl (aq) = MgCl2 (aq) + H2 (g)

by use of mole ratio between Mg to HCl which is 1 : 2 the moles of HCl is therefore

= 0.083 x2 = 0.166 moles

molarity of HCl = moles of HCl / volume in dm^3

that is 0.166/50 x1000 = 3.3 M of HCl

The balanced equation for the reaction between Mg and HCl is as follows;

Mg + 2HCl - - - > MgCl₂ + H₂

stoichiometry of Mg to HCl is 1:2

number of moles of Mg reacted - 2.00 x 10⁻³ g / 24 g/mol = 0.0833 x 10⁻³ mol

according to molar ratio

number of HCl moles reacted - 0.0833 x 10⁻³ x 2 mol = 0.167 x 10⁻³ mol

number of HCl moles in 50.0 mL - 0.167 x 10⁻³ mol

therefore number of HCl moles in 1000 mL - 0.167 x 10⁻³ mol / 0.0500 L

molarity of HCl - 0.00334 M