Question

Calculate the number of grams of sodium in 8.3 gg of each of the following sodium-containing food additives.

NaClNaCl (table salt)

Na3PO4Na3PO4 (sodium phosphate)

NaC7H5O2NaC7H5O2 (sodium benzoate)

Na2C6H6O7Na2C6H6O7 (sodium hydrogen citrate)

.

Answer 1

Mass of sodium in 8.3 g of NaCl

Number of moles of NaCl = Given mass/molecular mass = 8.3/58 = 0.143

number of moles of NaCl = Number of moles of Na

Mass of sodium in 8.3 g of NaCl = Number of moles of sodium * molar mass of sodium = 0.143* 23 = 3.29g

Mass of sodium in 8.3 g of Na3PO4

Number of moles of Na3PO4 = Given mass/molecular mass = 8.3/164 = 0.05

Number of moles of Na = 3 * number of moles of Na3PO4 = 3*0.05 = 0.15

Mass of sodium in 8.3 g of Na3PO4 = Number of moles of sodium * molar mass of sodium = 0.15 * 23 = 3.45

Mass of sodium in 8.3 g of NaC7H5O2

Number of moles of NaC7H5O2 = Given mass/molecular mass = 8.3/144 = 0.057

number of moles of NaC7H5O2 = Number of moles of Na

Mass of sodium in 8.3 g of NaC7H5O2 = Number of moles of sodium * molar mass of sodium = 0.057* 23 = 1.32g

Mass of sodium in 8.3 g of Na2C6H6O7

Number of moles of Na2C6H6O7 = Given mass/molecular mass = 8.3/236 = 0.035

Number of moles of Na = 2 * number of moles of Na2C6H6O7 = 2*0.035 = 0.07

Mass of sodium in 8.3 g of Na2C6H6O7 = Number of moles of sodium * molar mass of sodium = 0.07 * 23 = 1.61g