Step-by-step explanation:
First, let's write the balanced equation of formation of MgCl2 from Mg and Cl2:
Mg + Cl2 → MgCl2
Now let's transform 10.0g of Mg into moles, using the following formula: moles = mass/molar mass
molar mass of Mg = 24.3 g/mol
moles = 10/24.3
moles = 0.412 moles
Now we use the equation ratio between Mg and MgCl2 to find the quantity of MgCl2 in moles.
1 mole of Mg produces 1 mole of MgCl2.
So 0.412 moles of Mg produces 0.412 moles of MgCl2.
Now we transform 0.412 moles of MgCl2 into mass using the following formula: mass = moles x molar mass
Molar mass of MgCl2: 24.3 + (2*35.45) = 95.21 g/mol
Mass = 0.412 * 95.21
Mass = 39.2 g
Answer: The theoretical yield of MgCl2 is 39.2 g.