Question

define the formula unit mass and calculate the formula unit mass of N a 2 CO 3 10 H2O and Cll 4

Answer 1

The molar mass of Na2 CO3 • 10H2 O is 286.1412 g/mol.

We have to multiply the molar masses of each element by the quantity of each respective element in the compound. We'll deal with the 10 water molecules later.

Two sodium atoms

(2)(22.989769 g/mol) = 45.9795 g/mol Na

One carbon atom

(1)(12.0107 g/mol) = 12.0107 g/mol

Three oxygen atoms

(3)(15.9994 g/mol) = 47.9982 g/mol

This gives us a total of 105.9884 g/mol

The molar mass of 10 water molecules is:

20 hydrogen atoms

(20)(1.00794 g/mol) = 20.1588 g/mol

10 oxygen atoms

(10)(15.9994 g/mol) = 159.994 g/mol

This gives us a total of 180.1528 g/mol

Now we total the molar mass of sodium carbonate and the ten water molecules giving us:

105.9884 g/mol + 180.1528 g/mol = 286.1412 g/mol