If 100.0 grams of na3n decompose to form sodium and nitrogen, how many moles of sodium are formed? write and balance equation before solving

3.62 moles

Explanation:

Sodium nitride (Na₃N) will decompose as shown in the balanced equation below

2Na₃N → 6Na + N₂

The molar mass of sodium nitride in the solution is

Mass of Na above is (2 ₓ 3 ₓ 23) = 138 g

Mass of N above is (2 ₓ 14) = 28 g

Mass of Na₃N = 138g + 28g = 166g

From the equation above, we can deduce that 166g of Na₃N will produce 6 moles of sodium. Hence 100g of Na₃N will produce X moles of sodium where X is unknown.

∴ 166g of Na₃N →  6 moles of Na

100g of Na₃N → X moles of Na

When the above is cross multiplied,

X =

X = 3.62 moles

3.62 moles of sodium (Na) will be formed when 100g of Na₃N decomposes

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%