Question

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

Answer 1

Answer:

We need 11.35 grams of MgO

Explanation:

Step 1: Data given

Mass of Fe2O3 = 15.0 grams

Molar mass Fe2O3 = 159.69 g/mol

Step 2: The balanced equation

3MgO(s) +  2Fe(s) →  Fe2O3(s) + 3Mg(s)

Step 3: Calculate moles Fe2O3

Moles Fe2O3 = mass Fe2O3 / molar mass Fe2O3

Moles Fe2O3 = 15.0 grams / 159.69 g/mol

Moles Fe2O3 = 0.0939 moles

Step 4: Calculate moles MgO

For 3 moles MgO we need 2 moles Fe to produce 1 mol Fe2O3 and 3 moles Mg

For 0.0939 moles Fe2O3 we need 3* 0.0939 = 0.2817 moles MgO

Step 5: Calculate mass MgO

Mass MgO = moles MgO * molar mass MgO

Mass MgO = 0.2817 moles * 40.30 g/mol

Mass MgO = 11.35 grams

We need 11.35 grams of MgO

Answer 2

Answer:

Balanced reaction:

3MgO + 2Fe -> 3Mg + Fe2O3

11.3 g of MgO are needed to produce 15 g of Fe2O3

Explanation:

The balanced reaction is:

3MgO + 2Fe -> 3Mg + Fe2O3

Ratio is 1:3. First of all we determine the moles of produced oxide.

15 g . 1mol / 159.7 g = 0.0939 moles.

Now, the rule of three:

1 mol of oxide was produced by 3 moles of MgO

Then, 0.0939 moles of oxide were produced by 0.282 moles.

If we convert the moles to mass, we will get the answer 0.282 mol . 40.3g / 1mol = 11.3 g