Question

want to know how they calculated the amount of Na2CO3 to use for the stoichiometry. thanks

Answer 1

Solution.

The amount of substance (n) can be found from its mass (m) and molar mass (M).

The molar mass of any substance can be calculated from the atomic masses of the constituent elements, multiplied by the corresponding indexes.

M(Na₂CO₃) = 2M(Na)+M(C) + 3M(O) = 2*23+12+3*16 = 106 g/mol.

Therefore, the amount of Na₂CO₃ to use for the stoichiometry is

the units of the amount of substance are moles.

The reaction is

Na₂CO₃+CaCl₂*2H₂O = CaCO₃(s) + 2NaCl + 2H₂O.

The reaction stoichiometry says that 1 mole of Na₂CO₃ reacts with 1 mole of CaCl₂*2H₂O to produce 1 mole of CaCO₃(s), 2 moles of NaCl and 2 moles of H₂O.