Compute the number of molecules of water driven off when 12.05g of sodium acetate trihydrate is heated.
To compute the number of molecules of water driven off when 12.05g of sodium acetate trihydrate is heated, we need to first calculate the number of moles of sodium acetate trihydrate present.
Step 1: Determine the molar mass of sodium acetate trihydrate.
Sodium acetate trihydrate has the formula NaCH3COO·3H2O.
The atomic masses are:
Na (sodium) = 22.99 g/mol
C (carbon) = 12.01 g/mol
H (hydrogen) = 1.01 g/mol
O (oxygen) = 16.00 g/mol
Molar mass of sodium acetate trihydrate:
= (22.99 g/mol) + (12.01 g/mol) + (3 * (1.01 g/mol)) + (3 * (16.00 g/mol))
= 136.09 g/mol
Step 2: Calculate the number of moles of sodium acetate trihydrate.
Number of moles = mass / molar mass
= 12.05 g / 136.09 g/mol
≈ 0.0885 mol
Step 3: Since sodium acetate trihydrate has three water molecules (H2O) per formula unit, we can convert the number of moles of sodium acetate trihydrate to the number of moles of water molecules.
Number of moles of water molecules = 0.0885 mol * 3
= 0.2655 mol
Step 4: Finally, calculate the number of molecules of water.
Number of molecules = number of moles * Avogadro's number
= 0.2655 mol * 6.022 x 10^23 molecules/mol
≈ 1.6 x 10^23 molecules
Therefore, approximately 1.6 x 10^23 water molecules are driven off when 12.05g of sodium acetate trihydrate is heated.