Thomas has 235 grams of K2S in the chemistry lab. How many atoms of potassium (K) are in 235 grams of the compound?

The number of atoms of K that are in 235 g of the compound is

2.57 x10^24 atoms

calculation

Step 1: find the moles of K2S

= moles = mass/molar mass

= 235 g/110 g/mol = 2.136 moles

Step 2: multiply 2.136 moles by no. of K atoms in K2S

= 2.136 x2 = 4.272 moles

Step 3: use the Avogadro's law to determine number of K atoms

that is according to Avogadro's law 1 mole = 6.02 x 10^23 atoms

4.272 moles=? atoms

by cross multiplication

= (4.272 moles x 6.02 x10^23 atoms) / 1 mole = 2.57 x10^24 atoms