Answer:
2.8 moles
Step-by-step explanation:
Data obtained from the question include:
Percentage composition of N2 in air = 78%
Molar mass of N2 = 28g/mol
Mass of air = 100g
Number of mole of N2 =..?
Next, we shall determine the mass of N2 in air. This can be obtain as follow:
Mass composition of N2 in air = 78% of 100
= 78/100 x 100 = 78g
Therefore, the mass of the N2 in air is 78g
Finally, we shall determine the number of mole of N2 as follow:
Molar mass of N2 = 28g/mol
Mass of N2 = 78g
Number of mole of N2 =.?
Mole = mass /Molar mass
Number of mole of N2 = 78/28
Number of mole of N2 = 2.8 moles.
Therefore, 100g of air contains 2.8 moles of N2