Mass Ratio Puns

Dog’s urine contains a compound of potassium and phosphorus. The compound is being analyzed as below:

Mass of an empty test–tube = 10.183 grams

Mass of test–tube + compound = 10.947 grams

Mass of test–tube + potassium after compound is thermally decomposed and phosphorus is evaporated away = 10.885 grams.

Calculate the empirical formula of this compound (Ar: P = 31, K = 39).

Answer

>!Mass of compound = 0.764 grams, mass of phosphorus = 0.062 grams, mass of potassium = 0.702 grams!<

>!Converting the elemental masses into moles: mole of P = 0.062/31 = 0.002 and mole of K = 0.702/39 = 0.018!<

>!Divide 0.018 by 0.002 gives a mole ratio of P : K = 1 : 9!<

>!Therefore the formula of the compound is canine pee (K9P).!<