Friday, February 3, 2012

Practice Questions of Stiochiometry


Practice Questions

XI-AKUEB
Topics: (Stiochiometry
Q.1
1        When 142 g  of calcium fluoride are reacted with an excess of sodium
bromide, calculate the mass of calcium bromide formed.
2.         How many  grams of sodium aluminate can be  obtained from 7.71  g of
aluminum chloride according to the reaction:  
AlCl3(aq)  +  4NaOH(aq) = ¼  NaAlO2(aq)  +  3NaCl(aq)  +  2H2O(l)
3).  How many  grams of carbon dioxide  are obtained when 2.96  g of
cerium(III) oxalate are formed according to the reaction:
2Ce(IO3)4(aq) + 24H2C2O4(aq)= ¼ Ce2(C2O4)3(aq) + 4I2(aq) + 42CO2(g) + 24H2O(l)
4).  Calculate the mass of sodium permanganate that can be prepared from
1.27 g of sodium bismuthate according to the reaction:
2Mn(NO3)2 + 5NaBiO3 + 14HNO3 = ¼ 2NaMnO4 + 5Bi(NO3)3 + 3 NaNO3 + 7H2O
5).  If excess sulfuric acid is reacted with sodium hydroxide, 15.0 g of water
is formed.  What mass of sodium hydroxide was used?
6). 50.0 g of calcium carbonate was added to excess phosphoric acid.  What
mass of calcium phosphate was formed?
7).  Calculate the  mass of barium nitrate that must decompose in order to
produce 112 g of oxygen.
8). Calculate the mass of potassium chloride  that  is produced when  17.0 g of
potassium carbonate reacts with hydrochloric acid.

9).  When “x” grams of calcium chloride  was reacted with an excess of
bromine, 14.0 kg of a gas was formed.  Calculate “x”.
10). How many grams of zinc oxide are formed when 10.0 g of zinc reacts with
oxygen?
11. Sodium nitrate decomposes to give 3.00 g of oxygen.  Calculate the mass
of sodium nitrate used.
12. Potassium  metal reacts with 70.0  g of chlorine.  Calculate the mass of
product.
13. Calculate  the  mass  of magnesium oxide that must be decomposed in
order to produce 48.0 g of oxygen.
14).    Sodium chloride was reacted with an excess of sulfuric acid to  give
hydrochloric acid and 142 g of a second product.  What is the product,
and how much sodium chloride was reacted?
15. What mass of copper(I) sulfide can be produced from 9.90 g of copper(I)
chloride reacting with an excess of hydrogen sulfide gas?
16. How many grams of calcium hydroxide will be needed to react completely
with 10.0 g of phosphoric acid?
17. How many grams of hydrogen can be produced from the reaction of 72.0
g of sodium with an excess of water?
18. An excess of nitrogen reacts with 6.57 g of hydrogen.  How many grams
of ammonia are produced?
19. How many grams of oxygen are required to burn completely 84.9 g of
carbon?  C(s)  +  O2(g) = ¼  CO2(g)
20. In the decomposition of potassium chlorate, 82.6 g of oxygen are formed.
How many grams of potassium chloride are produced?
21. The action of carbon monoxide can be expressed by the equation,
Fe2O3(cr)  +  3CO(g) = ¼ 2Fe(s)  +  3CO2(g)
What would be the minimum amount of carbon monoxide used if 80.3 g of
iron were produced?
22. How many  grams of  hydrochloric acid are required to react completely
with 44.7 g of calcium hydroxide?
23. How many grams of hydrogen are produced when 4.77 g of aluminum react
with excess hydrochloric acid?
24. Calculate the mass of lithium carbonate that must decompose to produce
78.0 g of carbon dioxide.
25. How many grams of oxygen gas are formed when 100.0 g of magnesium
chlorate are decomposed?
26. Hydrochloric acid was reacted with  zinc to produce 137 g of hydrogen
gas.  What mass of zinc did you begin with?
Q.2
Stoichiometry - Limiting Reactants
1.  Hydrogen gas can be produced in the laboratory by the reaction of magnesium metal
with hydrochloric acid.
a)  How many grams of hydrogen can be produced when 4.00 g of hydrochloric acid
are added to 3.00 g of magnesium?
b)  What is the volume of this hydrogen at standard conditions?
2.  Potassium  nitrate  is widely used as a fertilizer because it provides two essential
elements, potassium and nitrogen.  It is made by mixing potassium chloride and nitric
acid in the presence of oxygen according to the equation:
4KCl  +  4HNO3  +  O2   =  4KNO3  +  2Cl2  +  2H2O

How many kilograms of potassium nitrate will be produced from 50.0 kg of potassium
chloride  and 50.0 kg of nitric acid?  An important by-product is chlorine.  How many
kilograms of chlorine will be produced?
3.  Phosphorus forms a compound similar to ammonia.  The compound has the formula PH3
and is called phosphine.  It can be prepared by the reaction:
P4  +  3NaOH  +  3H2O  = ¼   PH3  +  3NaH2PO2
If 20.0 g of phosphorus and 50.0 g of sodium hydroxide are reacted with excess water,
how many grams of phosphine will be obtained?
4. Bromine can be prepared  by  adding  chlorine  to  an  aqueous  solution  of  sodium  bromide.
How many grams of bromine  are  formed  if 25.0 g of sodium bromide and 25.0 g of
chlorine are reacted?
5.  Silver  tarnishes  in the presence of hydrogen sulfide, a gas that originate from the
decay of food, because of the reaction:
4Ag  +  2H2S  +  O2 =  ¼   2Ag2S  +  2H2O
The black product, silver sulfide, is the  "tarnish".  If  25.00 g of silver, 5.00 g of
hydrogen sulfide, and 4.00 g of oxygen are present in a reaction mixture, which one is
the limiting reactant, and what mass of silver sulfide is produced?
6.  Sulfur dioxide  can be produced from the  reaction of hydrogen sulfide and oxygen as
shown by the following reaction:  2H2S  +  3O2 =  ¼   2SO2  +  2H2O
a)  How many grams of sulfur dioxide can be produced from 70.0 g of hydrogen
sulfide and 125 g of oxygen.
b)  How many grams of excess reactant are left over after the reaction is complete?
7.  What mass of carbon disulfide is produced when 17.5 g of carbon are reacted with 39.5
g of sulfur dioxide according to the equation:
5C(s)  +  2SO2(g) =  ¼  CS2(s)  +  4CO(g)
8.  What mass of P4  is  produced  when  41.5  g  of  Ca3(PO4)2, 26.5 g of SiO2 and 7.80 g of C
are reacted according to the equation:
2Ca3(PO4)2 + 6SiO2 + 10C= ¼ P4 + 6CaSiO3 + 10CO
9. What  volume  of  carbon  dioxide,  measured  at  STP,  can  be  produced  when  15.65  g  of
pentane is reacted with 40.0 L of oxygen, measured at STP, according to the equation:
C5H12(l) + 8O2(g) = ¼ 5CO2(g) + 6H2O(l)
10.  What mass of hydrogen chloride gas is produced when 4.50 g of hydrogen and 140.0 g
of chlorine are reacted.  Which reactant is in excess and how much remains unreacted?
11.  The roasting of siderite ore, FeCO3, produces ferric oxide:
4FeCO3(s) + O2(g) ¼ 2Fe2O3(s) + 4CO2(g)
What mass of ferric oxide is produced when 55.0 g of siderite is reacted with 40.0 L of
oxygen gas?  Which reactant is in excess and how much remains unreacted?
12.  A manufacturer of bicycles has 5050 wheels, 3013 frames, and 2455 handlebars.
a)  How many bicycles can be manufactured using these parts?
b)  How many parts of each kind are left over?
c)  Which part is like a limiting reactant in that it limits the production of bicycles?
13.  The fizz produced when an  Alka-Seltzer  tablet is dissolved in water is due to the
reaction between sodium bicarbonate and citric acid:
3NaHCO3(aq) + H3C6H5O7(aq) ¼ 3CO2(g) + 3H2O(l) + Na3C6H5O7(aq)
In  a  certain  experiment 1.00 g of sodium  bicarbonate and 1.00 g of citric acid are
allowed to react.
a)  What volume of carbon dioxide is formed?
b)  Which reactant is the limiting reactant?
c)  How much of the excess reactant remains after the limiting reactant is
completely consumed?
14.  One of the steps in the commercial process for converting ammonia  to  nitric acid
involves the conversion of ammonia to nitrogen monoxide:
2NH3(g) + 5O2(g) = ¼ 4NO(g) + 6H2O(g)
In a certain experiment 2.50 g of ammonia reacts with 2.85 g of oxygen.
a)  What mass of nitrogen monoxide is formed?
b)  Which reactant is the limiting reactant?
c)  How much of the excess reactant remains after the limiting reactant is
completely consumed?

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