Question

Balance the chemical equation given below, and determine the number of grams of MgO needed to produce 15.0 g of Fe2O3.
___ MgO(s) + ___ Fe(s) ? ___ Fe2O3(s) + ___ Mg(s)

Answer 1

Hello!

Our first step is to balance the reaction equation:

3 MgO + 2 Fe = Fe₂O₃ + 3 Mg

Next, we need to convert the 15.0 grams of Fe2O3 to moles using it's molar mass (159.69 grams/mole):

Next, we use the balanced reaction equation to determine how many moles of MgO are needed to make 0.094 moles of Fe2O3. We see from the equation that we need 3 moles of MgO to create 1 mole of Fe2O3:

Our last step is to convert the 0.282 moles of MgO to grams using its molar mass (40.30 grams/mole):

That's all there is to it!

I hope this helps! Please rate if it does : )

Answer 2

3MgO + 2Fe --> Fe2O3 + 3Mg

molar mass of Fe2O3 = 159.6 g/mol
# moles of Fe2O3 = 15g/ 159.6 g/mol = 9.4x10^-2 mol
molar ratio of Fe2O3 to MgO is 1 : 3
therefore, we multiply 9.4x10^-2 by 3
= 2.8x10-1 mols of MgO
molar mass of MgO = 40.3 g/mol
mass of MgO = 2.8x10^-1 mols x 40.3g/ mol
= 11.3 g of MgO