Answer:
m = 190. g MgCl2
Step-by-step explanation:
Use a molar ratio to get the # of moles MgCl2 produced from 4.00 mol of HCl:
4.00 mol HCl × (1 mol MgCl2/2 mol HCl) = 2.00 mil MgCl2
So 2.00 moles of MgCl2 will be produced. To find the mass in grams, use the molar mass of MgCl2:
2.00 mol MgCl2 × (95.211 g MgCl2/1 mol MgCl2)
= 190. g MgCl2