posted by Alex on .
If 0.0900 g of a metal, M, reacts with excess hydrochloric acid to form 5.00*10(exp.)-3 moles of hydrogen gas and a solution of MCl(subscript)3. Calculate the molar mass of metal, M and identify it. The unbalanced equation is: M(s)+ HCl(aq) =>MCl(sub.)3 + H(sub)2.
Now that the SUBJECT has been stated, one of our chem teachers may notice it and respond
Balance the equation.
2M + 6HCl ==> 2MCl3 + 3H2
Convert moles H2 to moles M using the coefficients in the balanced equation.
0.0053 moles H2 x (2 moles M/3 moles H2) = 0.0053*(2/3) = 0.003333
moles = grams/molar mass and rearrange to
molar mass = grams/moles. You have grams in the problerm (0.0900 g) and moles from the calculation; solve for molar mass, then look on the periodic table to find a metal with that atomic mass.