Assignment 2

1. Hydrocarbons are molecules that contain only carbon and hydrogen. List below is the carbon content per gram of substance for several common hydrocarbons;

Hydrocarbon Grams of Carbon per Gram of Hydrocarbon

A 0,828B 0,750C 0,800D 0,818

a). For hydrocarbons list in the table, calculate the mass of hydrogen that combines with 1 gram of carbon.b). Determine small-number ratios of hydrogen atoms per carbon atom for the hydrocarbons in the table.c). Write empirical formulas for the hydrocarbons in the table.

~Answer~a) Hydrocarbon A

massof carbonmassof hydrogen

=massof carbon referedmassof hydrogen refered

0,8280,172

=1x

0,828x = 0,172 x = 0,2 gram

Hydrocarbon B

massof carbonmassof hydrogen

=massof carbon referedmassof hydrogen refered

0,7500,250

=1x

0,750x = 0,250 x = 0,33 gram

Hydrocarbon C

massof carbonmassof hydrogen

=massof carbon referedmassof hydrogen refered

0,8000,200

=1x

0,800x = 0,200 x = 0,25 gram

HydrocarbonD

massof carbonmassof hydrogen

=massof carbon referedmassof hydrogen refered

0,8180,182

=1x

0,818x = 0,182 x = 0,22 gram

b). Hydrocarbon ACAr C

:HAr H

0,828

12:

0,1721

0,069 : 0,172 1 : 2,5

Hydrocarbon BCAr C

:HAr H

0,750

12:0 ,250

1

0,0625 : 0,25 1 : 4

Hydrocarbon CCAr C

:HAr H

0,800

12:

0 ,2001

0,067 : 0,2 1 : 3

Hydrocarbon DCAr C

:HAr H

0,81 8

12:0,18 2

1

0,068 : 0,182 1 : 3

c). Hydrocarbon AH2,5C1 x 2 = H5C2

Hydrocarbon BH4C = CH4

Hydrocarbon CH3C = CH3

Hydrocarbon DH3C = CH3

2. Aspirin contains C, H and O in the following mass percents; C 60%; H 4,48% and O 35,52%.a). Is aspirin likely to be an ionic compound or a molecular compound?

b). What is possible formula for Aspirin?

~Answer~a). Aspirin is a molecular compound.

b). C = 60% H = 4,48% O = 35,52%

nC = 6012

=5mol

nH = 4,48

1=4,48mol

nO = 35,52

16=2,22mol

>>> Smallest RatioC : H : O5 : 4,48 : 2,22____________: 2,222,25 : 2 : 1____________x 49 : 8 : 4 C9H8O4