Mg + 2hcl --> mgcl2 + h2 if 4.8 moles of hcl reacts with excess magnesium, how many moles of magnesium chloride will be produced?

Taking stoichiometry in to consideration, take 1/2 of moles of HCl for moles of MgCl2. Use the equation n=m/M where

n = moles

m = mass

M = molar mass

[please do give the molar masses with the question. So if CONSIDERING molar mass of Mg = 24gmol^-1 and CL = 35.5gmol^-1]

M(MgCl2) = 95gmol^-1

m= n×M

m = 2.4 × 95 =228gmol^-1

the ratio of the conjugate base to the acid required to attain the desired ph.