You are asked by your teacher to buy 10 mol of distilled water from a shop where small bottles each containing 20 g of such water are available . How many bottles will you buy ?

Explanation

Molecular mass of water `(H_(2)O) = 18 `.
`therefore` 10 mol of distilled water = `18 xx 10= 180` g .
Because 20 g distilled water is contained in 1 bottle ,
180 g of distilled water is contained in `(180)/(20)` bottles = 9 bottles .
`therefore` number of bottles to be bought = 9 .