Mole and
Avogadro Number:
1. The atomic weight of Gold is 197.2 a.m.u. What is the
weight of one Gold atom?How many gram atoms are in 7.58g of Au?
2. A sample of chlorine gas at S.T.P. has a volume of
800cm3
calculate;
a)The number of moles
chlorine
b)The mass of the sample
c) The number of
chlorine molecules in the sample
3.
How many atoms of carbon are present in 10g of coke
4.
10g of Na contain as many no. of atoms an in 10g of K
5. The atomic mass of Zn is 65.4 a.m.u.
a)The number of moles and also the number of atoms in
10.9g of Zn
b)The mass of 1.204 x 1024 atoms of Zn
6.
The molecular
weight of NaOH is 40; find
a)Its gram molecular weight.
b)Weight of 3 molecules in a.m.u.
c)Weight of 60200 molecules in gram
d) Weight of 6 Gram mole
7. Atomic mass of Na = 23 a.m.u.; Calculate
(i)
Number of mole in
460g of Na
(ii)
Mass of 3.01* 1023
atoms of Na
(iii)
Number of atoms
in 4.6g of Na
8.
Calculate the
number of moles and the number of molecules present in 9.0 gm of C6H12O6
9.
Calculate the
number of moles, the number of molecules and
the volume in cm3 of 0.32gm of a ) CH4 b) SO2 gases at S.T.P.
10.The
atomic mass of sodium (Na) = 23 a.m.u.
a) Calculate
the mass of 2.408 x 1023 atoms of Na
b) Calculate the number
of moles of Na in 4.6gm.
11.
What is the mass of 3.01 x 1022 molecules of N2?
Empirical and Molecular Fromula:
1. The empirical formula of a compound is CH2O.
If the molecular weight of the compound is 180; calculate the molecular formula
2. Calculate the Empirical formula from the given
percentage composition 68.8% carbon 5.0% Hydrogen 26.2% Oxygen
3. A given compound contain C = 60%, H = 13%, O = 27%
Calculate
its Empirical formula.
4. 1g of a sample of an organic substance was burnt in
excess of oxygen yield 3.03g of CO2 and 1.55g of H2O. if
the molecular mass of the compound is 58 a.m.u.; find the molecular formula.
5.
A given compound
contain 75.2% carbon 10.75% hydrogen and 14.05% oxygen; calculate the empirical
formula of the compound.
6.
Adipic acid used
in the manufacture of Nylon the acid contain 49.3% carbon, 6.9% hydrogen and
43.8% oxygen by mass, the molecular mass 146 a.m.u. find the molecular formula
of Adipic acid.
7.
A compound
contain 40% carbon, 6.66% hydrogen by mass. Its
molecular mass if double that of its empirical mass.
Find Molecular formula.
8.
An organic
compound contain 51.8% carbon, 13.12% hydrogen and 35.08% oxygen; determine the
empirical formula of the compound
(C = 12 a.m.u. , H = 1a.m.u., O = 16
a.m.u).
9.
A hydrocarbon ha
20% hydrogen and 80% carbon: find the
empirical and molecular formula o the compound if the molecular mass is 30.
10. Diethyl zinc is
a chemical used in the library to produce the books from the worms. Its
composition is 53% zinc, 38.9% carbon and 8.1% hydrogen; find the empirical
formula of the compound.
11. An organic
compound contains 67.7% of C and 7.41% of H, and 25.90% of N. the molecular
mass of the compound is 108. Determine the empirical and molecular formulae of
the compound.
12. The molecular
mass of a compound is 180 and its empirical formula is CH2O: find
the molecular formula.
Stoichiometry:
1. 30gm of lime stone (calcium carbonate CaCO3)
was heated,
a) Write the equation of
the reaction
b) Calculate the mass of
CO2 produced
c) Calculate the volume
of CO2 at S.T.P.
2. 73.5gm of KClO3 is decomposed on heating
as follows:
2KClO3 2KCl +
3O2
Calculate: a) The mass of KCl formed
b) The volume of O2 formed at S.T.P.
3.54 gram of Dinitrogen pentaoxide (N2 O5)
is decomposed in
heating as
2N2O5 4NO2 + O2
Find the volume of NO2
and O2 produce at S.T.P.
4.
Calculate the
volume of oxygen gas at N.T.P. required to burn 30g of CH4 gas as
shown in the following reaction.
CH4 + O2 CO2
+ 2H2O
5.
Calculate the
volume of nitrogen gas produce by heating 300g of ammonia gas at 21oC
and 823 torr pressure.
2NH3 N2 + 3H2
6. Calculate the volume of the oxygen at S.T.P. that may
be obtain by the decomposition of 51.3g of KClO3 of heating in
presence of catalyst.
2 KClO3 2KCl + 3O2
7.
Find the mass of
KCIO3, required to prepare 3.2 gm of O2.
2 KCIO3(s)
2KCl(s) + 3O2(g)
Limiting reactant:
1.
You are provided
with 6.0 gm of C and 100 gm of O2
Calculate the amount of CO2 prepared by
reacting them. Which of them is the limiting reactant?
2.
At high
temperature sulphur (S) combines with iron (Fe) to form brown black iron
sulphide (FeS)
Fe +
S FeS
In one experiment 76.2g of Fe are allowed to react
86.7g of sulphur; which of the two is limiting reactant; Calculate the amount
of FeS obtained.
3. Determine the mass of aluminum
acetate that can be made if You do this reaction with 125 g of acetic acid and
275 g of aluminum hydroxide
3CH3COOH
+Al(OH) 3 → Al(CH3COO) 3 +3H2O
What
is the limiting reactant in the above problem ? How much of Excess reagent will
be left over after the reaction is complete?
4
.Consider the following reaction:
3CaCO3 +2FePO4→
Ca3(PO4) 2
+Fe2 (CO3) 3
When 100 g of calcium carbonate anf 45 g of
iron(III)Phosphate .
What
is the limiting reactant in the above problem ? How much of Excess reagent will
be left over after the reaction is complete. What is the maximum amount of each
products that can be formed?
Theoretical and Actual
Yield
1. Calculate the theoretical yield of Calcium
Oxide if 24.8 g of Calcium carbonate decomposes. Calculate the percent yield if
we got 13.1 g in the laboratory .
CaCO3 →CaO + CO2
2. What is the percent yield if we experimentally produce 1.65g of copper
when 1.87g of Aluminum react with 9.65g of copper (II)sulphate .
2Al +CuSO4 → Cu + Al2(SO4)3
3. Find the theoretical yield of silicon carbide
if 50.0 g of silicon dioxide react with 79.1 g of Carbon .
SiO2 + C →
SiC +CO
4. What is the percent yield if 155 g of calcium carbonate is treated with
250g of hydrochloric acid 142g of calcium chloride is obtained .
CaCO3 + HCl →CaCl2 + CO2
+H2 O
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