Conversions involving Moles Constants I Periodic Table The

± Conversions involving Moles Constants I Periodic Table The mole is defined as the number of atoms in exactly 12 g of carbon-12. The mole equals 6022 × 1023 items of whatever you are counting. This number is also called Avogadro\'s number, after Amadeo Avogadro (1776-1856). Molar mass is the mass of 1 mol of atoms of an element, for compounds, molar mass is the mass of 1 mol of molecules or formula units. Molar mass can be used to convert mass to moles for any element or compound.

Solution

Part A

Weight of 4.2 mol of NaCl in grams:

1 mol of NaCl weighs 58.4 grams (definition of molar mass)

so 4.2 mol weighs = 4.2 mol x 58.4 g mol^-1 = 245.28 g

Part B

1 mol of water contains 6.022 x 10²³ molecules

1.75 mol of ice contains = 1.75 x 6.022 x 10²³ = 1.05 x 10²⁴ molecules