Question

How many grams of mgo are produced when 40.0 grams of o2 react completely with mg? 2 mg (s) + o2 (g) → 2 mgo (s)?

Answer 1

Answer: -

100 grams

Explanation: -

Mass of Oxygen = 40 g

Chemical formula of oxygen gas = O2

Molar mass of oxygen = 16 x 2 = 32 gram

Atomic mass of Mg = 24g

Molar mass of MgO = 24 x 1 + 16 x 1 =40 gram

The balanced chemical equation for the reaction is

2Mg + O2 -- > 2 MgO

So from the balanced equation we see that 1 O2 react to give 2 MgO

32 grams of O2 react to give 2 x 40 gram of MgO

40 grams of O2 react to give $\frac{2 x 40 gram x 40 gram}{32 gram}$

=100 gram of MgO