What is the mass % of oxygen in a 50.0 g sample of water?

Explanation:

The percent composition of a compound is the percent of total mass made up by a ... data for a reaction of iron and oxygen which produces an iron oxide compound. ... 80.0 g sample of a compound that was 20.0 g element X and 60.0 g element y then the ... How can I calculate the percent composition of water in a hydrate?

answer; i believe the correct answer is (solid gold);

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%