Calculations involving masses

Lithium, sodium and potassium are highly reactive metals in Group 1 of the periodic table.

When a freshly cut piece of potassium metal is exposed to air, it reacts rapidly with oxygen to form a dull layer of potassium oxide on its surface.

In a sample of this oxide, 0.78 g of potassium is combined with 0.16 g of oxygen.

Calculate the empirical formula of this potassium oxide. Relative atomic masses ( $A_r$ ): $O=16\text{O} = 16$ , $K=39\text{K} = 39$

You must show your working.

[3]

Calculations involving masses Questions

Lithium, sodium and potassium are highly reactive metals in Group 1 of the periodic table.

When a freshly cut piece of potassium metal is exposed to air, it reacts rapidly with oxygen to form a dull layer of potassium oxide on its surface.

In a sample of this oxide, 0.78 g of potassium is combined with 0.16 g of oxygen.

Calculate the empirical formula of this potassium oxide. Relative atomic masses ( $A_r$ ): $O=16\text{O} = 16$ , $K=39\text{K} = 39$

You must show your working.

[3]