Question

PLEASE ANSWER, I WILL GIVE BRAINLIEST AND THANKS!

Answer 1

Answer:

Mass  = 8 g

Explanation:

Given data:

Mass of MgO formed  = 20 g

Mass of oxygen needed = ?

Solution:

Chemical equation:

2Mg + O₂     →    2MgO

Number of moles of MgO:

Number of moles = mass/molar mass

Number of moles = 20 g/ 40 g/mol

Number of moles = 0.5 mol

Now we will compare the moles of MgO and O₂ from balance chemical equation:

                     MgO         :            O₂

                        2            :            1

                      0.5          :        1/2×0.5 = 0.25 mol

Mass of oxygen required:

Mass = number of moles × molar mass

Molar mass of O₂  is 32 g/mol

Mass = 0.25 mol × 32 g/mol

Mass = 8 g