How many grams of Oxygen are there in 15 g of sodium bicarbonate?

Question

Sodium bicarbonate (NaHCO3) is commercially known as baking soda.         

(Molar mass of NaHCO3 = 84.01 g/mol) 

Answer 1

First you can divide the given weight by the molar mass in order to get the number of moles

15 g / (84.01 g/mol) = 0.1786 mol NaHCO₃

the subscript on Oxygen is 3 which means that there are 3 moles of Oxygen atoms for every 1 mole of sodium bicarbonate

0.1786 mol x 3 mol / 1 mol = 0.5358 mol O₂

finally then you want to multiply by the molar mass of oxygen to convert over into grams

0.5358 mol O x 16.00 g/mol = 8.57 g O

meaning that there are 8.57 g of oxygen in 15 g of sodium bicarbonate

Answer 2

Find the molar mass of NaHCO₃

molar mass Na - 22.99 g

molar mass H - 1.01 g

molar mass C- 12.01 g

molar mass O - 16.00 g x 3 = 48 g

Total = 84.01 g , can round to 84 g

84 g NaHCO₃ = 48 g O (use this as conversion factor)

15 g NaHCO₃ x 48 g O = 8.57 g (rounded to 2 sig figs would be 8.6 g)

84 g NaHCO₃

Answer 3

Hello, Mimi,

We can calculate the percentage compositon of any of the elements in a compound by adding the atomic masses of each element and divide that mass by the total compiound mass to get a percentage. In this case. the three oxygen atoms account for 48 amu of the total 84 amu. That makes it 57.1% of the total.

15 grams*(0.5714) = 8.57 grams of O is 8.57 grams of oxygen atoms in 15 grams of NaHCO₃.

Bob