Question

Sodium carbonate hydrate has a molar mass of 286 g/mol. Given that the molar mass of anhydrous sodium carbonate is 106.0 g/mol and

the molar mass of water is 18.0 g/mol, which formula below is the formula for this hydrate?

Answer 1

Answer: To find the formula for the hydrate of sodium carbonate, we need to determine the number of water molecules (H2O) associated with one mole of anhydrous sodium carbonate (Na2CO3). We know that the molar mass of the hydrate is 286 g/mol and that of anhydrous sodium carbonate is 106.0 g/mol, and water is 18.0 g/mol.

Let's assume that there are "x" moles of water (H2O) associated with one mole of anhydrous sodium carbonate (Na2CO3).

Molar mass of the hydrate (Na2CO3·xH2O) = 286 g/mol

Molar mass of anhydrous sodium carbonate (Na2CO3) = 106.0 g/mol

Molar mass of water (H2O) = 18.0 g/mol

The molar mass of the hydrate (Na2CO3·xH2O) can be expressed as the sum of the molar masses of anhydrous sodium carbonate and "x" moles of water:

Molar mass of hydrate = Molar mass of Na2CO3 + x * Molar mass of H2O

286 g/mol = 106.0 g/mol + x * 18.0 g/mol

Now, let's solve for "x":

x * 18.0 g/mol = 286 g/mol - 106.0 g/mol

x * 18.0 g/mol = 180 g/mol

x = 180 g/mol / 18.0 g/mol

x = 10

So, there are 10 moles of water (H2O) associated with one mole of anhydrous sodium carbonate (Na2CO3). The formula for the hydrate is Na2CO3·10H2O.