Question

Calculate the moles of the following-
(a) 200g of sodium hydroxide
(b) 650g grams of hydrochloric acid​

Answer 1

$Number\:of\:moles = \frac{Mass\:of\:substance}{Mass\:of\:one\:mole}$

(a) Mass of NaOH = 200g (given)

Mass of one mole of NaOH =  Molar Mass of sodium + oxygen + hydrogen

= 23 + 16 + 1

= 40 g/mol

$Number\:of\:mole = \frac{200}{40}$

= 5 mol

(b) Mass of HCl = 650g (given)

Mass of one mole of HCl = Molar mass of hydrogen + Chlorine

= 1 + 34

= 35 g/mol

$Number\:of\:mole = \frac{650}{35}$

= 18.57 mol

Answer 2

Number\:of\:moles = \frac{Mass\:of\:substance}{Mass\:of\:one\:mole}Numberofmoles=

Massofonemole

Massofsubstance

(a) Mass of NaOH = 200g (given)

Mass of one mole of NaOH = Molar Mass of sodium + oxygen + hydrogen

= 23 + 16 + 1

= 40 g/mol

Number\:of\:mole = \frac{200}{40}Numberofmole=

40

200

= 5 mol

(b) Mass of HCl = 650g (given)

Mass of one mole of HCl = Molar mass of hydrogen + Chlorine

= 1 + 34

= 35 g/mol

Number\:of\:mole = \frac{650}{35}Numberofmole=

35

650

= 18.57 mol