How many moles of nitrogen are in 12 grams

Explanation:

The chemical formula of nitrogen is N2

A mol of Nitrogen atoms = 14 grams

So N2 will have a molar mass of 14 * 2 = 28 grams

number of moles of N2 = given mass / molar mass

number of moles of N2 = 12 / 28

number of moles of N2 = 0.4286 mols

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%