Question

Magnesium burns in air with a dazzling brilliance to produce magnesium oxide: 2Mg (s) + O2 (g) →→ 2MgO (s) When 4.50 g of magnesium burns, the theoretical yield of magnesium oxide is ________ g.

Answer 1

Answer:

Explanation:

2Mg (s) + O2 (g) →→ 2MgO (s)

The equation is already balance

Given that 4.5g of Mg yield Mg0

Then molar mass of each element

Mg=24g/mol

O2=16g/mol

2Mg= 2×24=48g/mol

2MgO=2(24+16)

2MgO=80g/mol

Then, the number of mol of Mg is

Molar mass=mass/mole

Mole=mass/molar mass

Mole=4.5/48

Mole=0.09375mole

Number of mole of magnesium is 0.09375mole

2 mole of Mg produce 2mole of MgO

Therefore they are in ration 1:1

Then 0.09375mole of Mg will produce 0.09375mole of MgO

Then the mass of MgO yield is

Mass=molar mass of 2MgO ×mole

Mass=80×0.09375

Mass=7.5g

Therefore, 7.5g of MgO will be yield

Answer 2

Answer:

7.46 g

Explanation:

From the balanced equation, 2 moles of Mg is required for 2 moles of MgO.

The mole ratio is 1:1

mole = mass/molar mass

mole of 4.50 g Mg = 4.50/24.3 = 0.185 mole

0.185 mole Mg will tiled 0.185 MgO

Hence, theoretical yield of MgO in g

mass = mole x molar mass

            0.185 x 40.3 = 7.46 g