Answer to Question #74340 in General Chemistry for Chloe Lozano

Question

When 45.0 mL of 4.8 M HCl reacts with an excess of Mg(OH)2, how many grams of Magnesium Chloride (MgCl2) are produced, given the unbalanced equation HCl + Mg (OH)2 → H2O + MgCl2?

A. 0.11 moles
B. 0.11 g
C. 0.22 moles
D. 0.22 g
E. None of the Above

Answer 1

2HCl +Mg(OH)2 = 2H2O + MgCl2
1. Find chemical amount of HCl in 45mL of solution:
1000mL of solution contain 4.8 mol of HCl,
45.0 mL of solution contain x mol of HCl;
We have a propotion 1000/45.0 = 4.8/x;
1000x =45.04.8;
x= 0.22;
n(HCl) = 0.22 mol.
2. Find chemical amount of MgCl2:
According to equation 2 moles of HCl give 1 mol of MgCl2,
We have: 0.22 moles of HCl give y moles of MgCl2;

2/0.216 = 1/y;
y = 0.11;
n(MgCl2) = 0.11 mol.
3. Find mass of MgCl2:
m = Mn;
M(MgCl2) = 24 + 35.52 = 95 (g/mol);
m( MgCl2) = 950.11 =10.45 (g).

There is no such value of mass in the answers proposed. Then the answer is E. None of the above.