Question

Iron(III) oxide is formed when iron combines with oxygen in the air. How many grams of Fe2O3 are formed when 33.4 g of Fe reacts completely with oxygen?
Molar Mass information: Iron = 55.8 g/mol, Oxygen= 15.9 g/mol

Answer 1

    The grams of  Fe₂O₃   that are formed is  47.68 g

calculation

Step 1: write   the equation for reaction

4 Fe +3O₂ → 2 Fe₂O₃

Step 2: find  the  moles  of Fe

moles = mass÷  molar mass

 = 33.4 g÷55.8 g/mol =0.5986 moles

Step 3 : use the mole ratio to determine the moles of Fe₂O₃

That is  from  equation above Fe:Fe₂O₃  is 4:2 therefore the moles of Fe₂O₃ is  =  0.5986 moles x 2/4 =0.2993 moles

Step 4 : find the mass  of Fe₂O₃

mass = mass x molar mass

The molar mass of Fe₂O₃  = (55.8 x 2 +(15.9 x3) = 159.3 g/mol

mass is therefore =  0.2993 moles x 159.3 g/mol =47.68 g

Answer 2

Answer:

47.8 g

Explanation: