When potassium is burned in air, one of the products is an orange-yellow solid, Y.
A sample of solid Y was found to contain 1.95 g1.95\text{ g}1.95 g of potassium and 0.80 g0.80\text{ g}0.80 g of oxygen. Show, by calculation, that the empirical formula of Y is KO\text{KO}KO. [Ar(K)=39A_r(\text{K}) = 39Ar(K)=39, Ar(O)=16A_r(\text{O}) = 16Ar(O)=16]
The relative formula mass of Y is 110110110. Deduce the formula of Y.
Solid Y reacts with water to form potassium hydroxide, KOH\text{KOH}KOH, and hydrogen peroxide, H2O2\text{H}_2\text{O}_2H2O2.
Write a chemical equation to represent the reaction between Y and water.
The solution formed in the reaction between Y and water turns red litmus blue. Identify the ion that causes this change.
The displayed formula for hydrogen peroxide is H−O−O−H\text{H}-\text{O}-\text{O}-\text{H}H−O−O−H. Complete the dot-and-cross diagram to show the arrangement of the outer shell (valence) electrons in a molecule of hydrogen peroxide.
