Can someone me on this chemistry problem? i keep messing up the dimensional analysis.

331 grams of hcl



to do this question, we need to balance the equation.
if we put a coefficient of 2 over hcl, then we will get 2 h atoms on the left side and 2 cl atoms on the right side.
this checks out with the right side. that's all the balancing you need to do.

   

we have 4.54 mol of mg(s).

   

we need to convert to grams of hcl.
according to the balanced chemical equation, there is 1 mol mg per 2 mol hcl. 

for our conversion factor, we need to put mg in the denominator so that it cancels out with mg.

   

molar mass of hcl is  36.46  grams per mol. put mol in the denominator so it cancels out with mol in numerator, so multiply:

   

   

331 grams of hcl

Adozen is 1221/12 = 1.751.75 x 12 = 21therefore, 1.75 is the answer.