Question

Determine the number of potassium atoms in 1.803g of potassium carbonate

Answer 1

K2CO3 mass = 1.803 g

K2CO3 moles = Mass of K2CO3 / ( molar mass of K2CO3)

             = (1.803 g) / ( 138.2 g/mol) = 0.013046

Number of K moles = Number of moles of K2CO3 x 2         ( since 1K2CO3 gives 2K)

          = 0.013046 x 2 = 0.0260926

Number of K atoms = Number of moles of K x avagdro number

             = 0.0260926 mol x 6.023 x10^23         ( where avagadro number = 6.023 x 10^23)

             = 1.57 x 10^22