HeLP! MOLeS ASSIGNMeNT! ASAP!?

1. Determine the molar mass of


(i) potassium


(ii) hydrogen gas


(iii) ammonium sulfate (NH4)2SO4.





2. Calculate the number of moles of nitrogen atoms in 46.00 g of nitrogen.





3. Determine the mass of 0.075 moles of sodium sulfate, Na2SO4.





4. In 126.036 g of nitric acid, HNO3, calculate the number of moles of:


(i) nitric acid molecules


(ii) hydrogen atoms


(ii) oxygen atoms





5. An alcohol molecule consists of 37.5% carbon, 12.6 % of hydrogen and 49.9% oxygen.


(i)Calculate the empirical formula of the alcohol.


(ii)If the molar mass of the alcohol is 32.042 gmol-1, determine its molecular formula.





6. Calculate the percentage, by mass, of chlorine in sodium hypochlorite NaOCl.





7.Octane undergoes complete combustion according to the equation:


2C8H18(l) + 25O2(g) = 16CO2(g)

HeLP! MOLeS ASSIGNMeNT! ASAP!?
1.


K = 39.1


H2 = 2.02


(NH4)2SO4 = 132





2. 46 / 14 = 3.28





3. Molar mass = 142 g/mol


0.075 mol x 142 g/mol = 10.65 g





4.


Moles HNO3 = 126.036 / 63 = 2.00


Moles H = moles N = 2.00


Moles O = 3 x 2 = 6.00





5.


37.5 / 12.011 = 3.12 ( C)


12.6 / 1.00794 = 12.5 (H)


49.9 / 15.9994 = 3.12


divide by the smallest number


CH4O empirical formula( mass = 32.042) =%26gt; molecular formula CH4O





6. Molar mass = 74.44 g/mol


22.9898 x 100 / 74.44 = 30.88 % Na


15.9994 x 100 / 74.44 = 21.49 % O


35.453 x 100 / 74.44 = 46.63 %