WorksheetsWhat's The Matter?
Total questions: 6
Worksheet time: 2hrs 30mins
Name
Class
Date
1.
Two naturally occurring isotopes of copper are 63Cu and 65Cu respectively. Given that the relative atomic mass of copper is 63.5. What is the percentage abundance of each isotope?
a)
63Cu = 75%
65Cu = 25%
65Cu = 25%
b)
63Cu = 35%
65Cu = 65%
65Cu = 65%
c)
63Cu = 50%
65Cu = 50%
65Cu = 50%
d)
63Cu = 80%
65Cu = 20%
65Cu = 20%
2.
Nitrogen is made up of two isotopes, N-14 and N-15. Respectively, the isotopic masses are 14.003074 and 15.000108. Given nitrogen's atomic weight of 14.007, what is the percent abundance of each isotope?
a)
N-14 = 0.7%
N-15 = 99.3%
b)
N-14 = 70.3%
N-15 = 29.7%
c)
N-14 = 99.3%
N-15 = 0.7%
d)
N-14 = 89.3%
N-15 = 1.7%
3.
Naturally occurring silicon consists of 3 isotopes, Si-28, Si-29 and Si-30, whose isotopic masses are 27.9769, 28.9765 and 29.9738 respectively. The most abundant isotope is Si-28 which accounts for 92.23% of naturally occurring silicon. Given that the observed atomic mass of silicon is 28.0855 calculate the percentages of Si-29 and Si-30 in nature.
a)
Si-29 = 66%
Si-30 = 34%
Si-30 = 34%
b)
Si-29 = 4.67%
Si-30 = 3.1%
Si-30 = 3.1%
c)
Si-29 = 25%
Si-30 = 75%
Si-30 = 75%
d)
Si-29 = 5%
Si-30 = 8%
Si-30 = 8%
4.
Dimethyl hydrazine, the fuel used in Apollo lunar module has a molar mass of 60.10g/mol. It is made up of carbon, hydrogen & nitrogen atoms. The combustion of 2.859g of the fuel in excess oxygen yields 4.190g of CO2 and 3.428g of H2O. What is the empirical formula for dimethyl hydrazine?
a)
CH4N
b)
CHN2
c)
CH3N
d)
C2H8N
5.
A 0.2500 g sample of a compound known to contain carbon, hydrogen and oxygen undergoes complete combustion to produce 0.3664 g of CO2 and 0.1500 g of H2O. What is the empirical formula of this compound?
a)
CH3O
b)
CH4O
c)
CHO
d)
CH2O
6.
Quinone, which is used in the dye industry and in photography, is an organic compound containing only C, H, and O. What is the empirical formula of the compound if you find that 0.105 g of the compound gives 0.257 g of CO2 and 0.0350 g of H2O when burned completely? Given a molecular weight of approximately 108 g/mol, what is its molecular formula?
a)
C6H2O4
b)
C6H4O2
c)
C4H6O2
d)
C8H8O8
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