Question

What mass of magnesium oxide is formed when 48.62g of magnesium is reacted with excess oxygen?

a) 80.62g
b) 40.31g
c) 38.90g
d) 20.00g
e) 48.62g

Answer 1

Answer: -

81.03 g magnesium oxide is formed when 48.62g of magnesium is reacted with excess oxygen

Explanation: -

Atomic mass of Mg = 24 g

Molar mass of MgO = 24 x 1 + 16 x 1

= 40 g

The balanced chemical equation for this reaction is

2 Mg + O₂ → 2MgO

From the balanced chemical equation we see

2 mol of Mg gives 2 mol of MgO.

2 x 24 g of Mg gives 2 x 40g of MgO.

48.62 g of Mg gives
`(2 x 40 g MgO)/(2 x 24 g Mg)` x Mg

= 81.03g of MgO