Answer to Question #262794 in General Chemistry for Sunshine Jimenez

Question

the chemical formula of washing soda is Na₂CO₃

a. what is the formula mass of washing soda?

b. what is the mass of 3.5 mol of washing soda?

c. how many formula units are there in 350g of washing soda?

Answer 1

Formula unit mass of Na₂

​CO₃

​

= 2×atomic mass of Na+1×atomic mass of C+3×atomic mass of O

=2×22.98+1×12.01+3×16

=105.97u

Formula unit mass of 10H₂ ​O

=10×atomic mass of H₂​O

=10×18.02

=180.02u

Formula unit mass of Na₂​CO₃​.10H₂​O

=105.97+180.02 

=285.99u

b)The molar mass of a compound defines the mass of 1 mole of that particular substance and the number of grams per mole of a compound. In other words, the molar mass is the total mass of all the atoms in grams that make a mole of a particular molecule

=3.5 x 285.99

=1004.4 g

c)Since sodium carbonate contains two atoms of sodium, one atom of carbon and three atoms of oxygen.

Na : 2 x 23.0 = 46

C : 1 x 12.0 = 12

O : 3 x 16 = 48

When we add up the total values i.e., 46 + 12 + 48 = 106

Therefore, the molar mass of Na₂CO₃ is 106 g/mole.