Answer to Question #211419 in General Chemistry for Jay

Question

Note:

1 mole of a compound is equivalent to its molecular mass

1 mole of a compound is equal to 6.02x10^23 molecules

The percentage is a direct equivalent to grams

Answers should be in 3 significant figures

No need to include the units and the compound in the answers

1. Determine the molecular formula of a compound with an empirical formula of NH2 and a formula mass of 32.06 u. 
2. A sample of a compound with a formula mass of 34.00 u is found to consist of 0.44 g H and 6.92 g O. Find its molecular formula. 

Answer 1

1.

NH₂ have emperical mass .

14 + 2 = 16 .

Given molecular mass = 32 .

n = 32 / 16 = 2 .

Molecular formula = 2 ( NH₂) = N₂H₄ .

2.

Given

moles of H = 0.44 / 1 = 0.44 mole .

moles of O = 6.92 / 16 = 0.44 mole .

molar ratio of H and O = 1: 1

So, emperical formula = HO .

Emperical mass = 1 + 16 = 17 .

Given molar mass = 34 .

n = 34 / 17 = 2 .

Molecular formula = 2 ( HO )

= H₂O₂ .