CHEMISTRY REVISION WORKSHEET

April
CHEMICAL REACTIONS AND EQUATIONS
SECTION A
1
Based on the video solve the questions that follows:
a (i) A chemical equation represent the _______ that actually takes place.
(ii) 1molecule of H2SO4 contains 2 Hydrogen , 1 Sulphur and 4 Oxygen atoms What does 1 molecule of Ca(OH)2 contain ?
(iii) Complete the following sentences:
 Chemical equation are balanced to satisfy the law of ________
 The number and type of all _______must be the same on both sides of the reaction arrow.
(iv) Write the following statement in the form of a balanced chemical equation :
One atom of sodium combines with one molecule of oxygen to give one molecule of sodium oxide.
(v) Construct chemical equation from the following:

2

(vi) Balance the following chemical equation:
 ____ N2 + ____ H2 → ____ NH3
 ____ KClO3 → ____ KCl + ____ O2
 ____ Pb(OH)2 + ____ HCl → ____ H2O + ____ PbCl2
 ____ AlBr3 + ____ K2SO4 → ____ KBr + ____ Al2(SO4)3
 ____ CH4 + ____ O2 → ____ CO2 + ____ H2O
 ____ Na + ____ H2O → ____ NaOH + ____H2
b
(i) In a chemical reaction ,one reactant breaks up to give two or more products.Name the reaction.
(ii) Identify the type of reaction and name the cations and anions.
P+T- + S+N- → P+N- + S+T-
(iii) You are provided with two ionic compounds-Sodium sulphate( Na2SO4) and barium chloride(BaCl2).
 Identify the positive ion(cations)and negative ions(anions) in each.
 Identify the type of reaction that will occur ,if you combine the above two reactants.
 write chemical equation for the chemical reaction taking place.
(iv) What do you mean by’ activity series of metals’
(v) What type of chemical reactions are represented by the following equations?
 A + BC → AC + B
 A + B → C
 X → Y + Z
 A2O3 + 2B → B2O3 + 2A
3
(vi)The following equations are based on synthesis or direct combination.
Complete and balance them
 Fe + Cl2 
 P2O5 + H2O 
 Fe + O2 
 N2 + H2 
 Al + N2 
 K2O + H2O 
 SO2 + H2O 
c A magnesium ribbon is burnt in oxygen to give a white compound ‘X’ accompanied by
emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it
continues to burn and form a compound ‘Y’
 Write the chemical formula of ‘X’ and ‘Y’.
 Write a balanced chemical equation, when ‘X’ is dissolved in water.
(i) Below are given two chemical reactions:
 H2 (g) + Cl2(g) → 2HCl (g)
 2AgCl(s) → 2Ag (s) + Cl2(g)
Which is a decomposition reaction and which is a combination reaction.
(ii) Calcium carbonate when heated gives rise to calcium oxide and carbon
dioxide.What type of reaction is this?What are the reactants and what
are the products?
(iii) Group the ions in the following reaction to depict a decomposition reaction.
 Na2SO4 (aq) + BaCl2 (aq) →
(iv) Complete the following double displacement reaction .
 KI + Pb(NO3)2 →
 Is there any precipitate formed?
 If any precipitate is formed , write the colour of the precipitate.
(v)Identify the reaction type from the following pictorial representation. How is this
different from double displacement reaction?

4
(vi) The process which involves gain of hydrogen or loss of oxygen is called ____________
(vii) What is reduction?
(viii) A ____________ is a substance which give hydrogen or gains oxygen.
2
Matter undergoes certain changes as a result of the application of energy. Glaciers melt in summer and rivers freeze in winter. Water from sea evaporates to form vapours , which forms clouds and then condenses to form rain.
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reaction can be either spontaneous, requiring no input of energy or non-spontaneous, often coming about only after the input of some type of energy i.e heat, light or electricity. Chemical reactions encompass changes that strictly involve the motion of electrons in the forming and breaking of chemical bonds, although the general concept o f a chemical reaction in particular the notion of a chemical equation, is applicable to transformation of elementary particles as well as nuclear reactions.
The substance/substances initially involve in a chemical reaction are called reactants. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants.
a
Fill in the blanks:
(i) Chemical reaction are the process in which ______ substances with new _____ are formed.
(ii) In chemical reaction the _____ obtained must have different properties from that of _____.
(iii) In a chemical reaction there must be either an _____ or an _____ of heat.
b
State true or false:
(i) In chemical reaction product obtained had same properties as that of a reactant.
(ii) In chemical reaction there is always a loss of matter.
c
What are chemical reactions?
d
What are reactants?
e
What do chemical reactions yield?
5
SECTION B
Choose the correct alternative:
1
Which amongst the following does not hold good for a balanced chemical equation?
a
Obeys law of conservation of mass
b
Has equal number of atoms of each element on both the sides of the equation
c
Mass of the reactants equal the mass of the product
d
Mass of the reactants is greater than mass of the products
2
Which amongst the following is used for white washing?
a
CaO mixed with water
b
CaSO4 mixed with water
c
Ca(OH)2 mixed with water
d
CaCO3mixed with water
3
White silver chloride changes to grey in sunlight because of the formation of silver metal along with the evolution of chlorine gas. Identify the chemical equation that gives a correct representation of the process.
a
2AgCl → 2Ag + Cl2
b
AgCl → Ag + Cl2
c
2Ag + Cl2 → 2AgCl
d
Ag + Cl2 → 2AgCl
4
In the following set up, the gas evolved turns lime water milky. Identify ‘X’.

a
dilute HCl
b
water
c
NaOH solution
d
calcium hydroxide
5
The given equation represents the reaction of sodium metal with water.
Sodium + Water→ Sodium hydroxide + Hydrogen
Which of the following chemical equations represents a complete balanced chemical
equation for the given word equation?
6
a
2Na(s) + H2O → 2 NaOH(aq) + H2(g)
b
Na(s) + 2H2O → NaOH(aq) +2H2(g)
c
2Na(s) + 2H3O → 2NaOH(aq) + 2H2(g)
d
2Na(s) + 2H2O → 2NaOH(aq) + H2(g)
6
Four students were asked to observe the effect of heat on lead nitrate crystals. The teacher provided them with test tube holders, test tubes and solid lead nitrate, The students then started heating lead nitrate as shown below. The teacher stopped three of them for using the wrong procedure.
The correct way of heating is

a
I
b
II
c
III
d
IV
7
Ritika noted the initial colour of the solutions in beakers I, II , III and IV. After inserting zinc rods in each solution and leaving undisturbed for two hours, she noted the color of each solution again. Mark the beaker in which colour change is observed?

a
I and II
b
II and III
c
III and IV
d
I and IV
8
Steps taken for performing the reaction between copper sulphate and iron are:
(i)prepare copper sulphate solution by dissolving a few crystals of copper sulphate in water.
(ii) put some iron nails in it.
(iii)leave it for five minutes.
(iv)observe the change in the colour of the solution
(v)take out the iron nails and observe for any deposit on it.
The result of the above experiment is not as expected. Identify the step that has been missed out.
a
heat copper sulphate solution before putting iron nails.
b
cool copper sulphate solution before putting iron nails.
c
rub the iron nails with sand paper.
d
close the test tube with a cork.
9
Study the following chemical equations:
Pb2+ + 2e-
Pb 2Br- - 2e-
Br2
(i) Lead ions gain electrons to form lead atoms
(ii) Bromide ions lose electrons to form bromine atoms.
(iii)The bromine atoms combine to form molecules of bromine gas.
(iv) Lead ions lose electrons to form lead atoms.
The correct statements for electrolysis of lead bromide is:
a
(i) , (ii) and (iii)
b
(i) , (ii) and (iv)
c
(i) , (iii) and (iv)
d
(ii) , (iii) and (iv)
10
Students were asked to study reaction between barium chloride and sodium sulphate.Four different reports of the experiment are given below. Choose the correct one.
S.No.
Procedure
Observation
A
Mixed powder of barium chloride and sodium sulphate
The colour of the mixture changes to yellow
B
Mixed solutions of barium chloride and sodium sulphate
Thick white precipitate is formed
C
Add solution of barium chloride to sodium sulphate powder
Solution becomes turbid
D
Add solution of barium chloride to sodium sulphate solution
No change is observed
Which one is correctly matched among the following?
a
B
b
C
c
D
d
A
8
11
Complete the following statement by choosing correct type of reaction for X and Y.
Statement 1: The heating of lead nitrate is an example of 'x' reaction
Statement 2: The burning of magnesium is an example of 'y' reaction.”
a
X
Y
combination
decomposition
b
X
Y
decomposition
combination
c
X
Y
combination
displacement
d
X
Y
displacement
decomposition
12
In the given figure, the red brown gas evolved is _______ .

a
Oxygen
b
Carbon dioxide
c
Nitrogen dioxide
d
Carbon monoxide
13
Which of the following changes will result in a substance with new chemical properties?
a
baking a cake
b
melting of ice cream
c
chopping a bunch of spinach
d
cooling a bottle of water in the fridge
14
Consider the following processes.
(i) rusting of iron
(ii) anti biotics fighting an infection
(iii)digestion of food in the stomach
(iv)photosynthesis in plants
(v)rising of cake in an oven
Which of the above are chemical interactions?
a
1 only
b
1 and 5 only
c
1,3 and 5 only
d
All- 1,2,3,4 and 5
9
15
Robinson discussed the gas -filled packet with his science teacher, and came to know that when the chips are packed, the air in the packets is replaced with nitrogen. Why are the packets filled with nitrogen?
a
Our body needs nitrogen and the chips absorb it.
b
Nitrogen is not a very reactive gas, so the chips remain fresh.
c
Nitrogen is not an inflammable gas, so it is safer to handle the packets.
d
Nitrogen contains only one type of atoms and is more hygienic than air.
16
Which chemical change corresponds to a reduction?
a
Calcium hydroxide reacts with acid waste gases from an industrial metal extraction process to form a harmless salt and water.
b
changing copper oxide into copper in a smelter.
c
carbon monoxide reacts with iron oxide to form carbon dioxide.
d
Calcium carbonate forms calcium oxide and carbon dioxide in the blast furnace extraction of iron.
17
A compound P is taken in a flask flat bottomed flask as shown in figure. Dilute hydrochloric acid is added drop by drop. A gas Q is evolved which is then passed in a test tube containing R. A solid precipitates S is formed is frequently used in white washing. During white washing a layer of R is applied on the wall and it reacts with gas Q(present in air) to produce white shiny layer of S on the wall.P , Q , R and S respectively are _____.

a
P= Na2SO4 : Q= SO2 : R= Ca(OH)2 : S= CaSO4
b
P= Na2SO3 : Q= O2 : R= Ca(OH)2 : S= CaO
c
P= Na2CO3 : Q= O2 : R= Ca(OH)2 : S= CaCO3
d
P= Na2CO3 : Q= CO2 : R= Ca(OH)2 : S= CaCO3
18
Complete the following statement by substituting X and Y with correct options
“Corrosion and rancidity are the result of ‘x’ reaction of iron articles and oils/fats
respectively. Galvanization is done to prevent corrosion of iron articles and ‘y’ are
used to prevent rancidity of oils or fats.”
10
a
X
Y
displacement
oxidants
b
X
Y
oxidation
anti -oxidants
c
X
Y
displacement
anti -oxidants
d
X
Y
combination
anti -oxidants
19.
Complete the following statement by choosing correct type of reaction for X and Y.
Statement 1: Heating of potassium chlorate in the presence of manganese dioxide as a catalyst is an example of X reaction.
Statemenr2: Burning of natural gas is an example of Y reaction.
a
X
Y
displacement
endothermic
b
X
Y
combination
decomposition
c
X
Y
displacement
endothermic
d
X
Y
decomposition
exothermic
SECTION C
1.
What is meant by skeletal equation?.Write one example of decomposition reaction in the form of balanced equation. (sample paper 2010)
2.
You are provided with two containers made up of copper and aluminium. You are also provided with solutions of zinc chloride and HNO3.In which of the above containers these solutions can be kept.
11
3.
Why does magnesium powder react much more rapidly than magnesium ribbon with dilute sulphuric acid?
4.
On adding dilute hydrochloric acid to copper oxide powder, the solution formed is blue
green. Predict the new compound formed which imparts a blue green color to the solution.
5.
Balance and identify the type of reaction in the following chemical equation:
(OD 2008)(Sample paper 2011-12)
a
Fe (s) + H2O (g) → Fe3O4 (s) + H2 (g)
b
heat
CaCO3 (s) → CaO (s) + CO2 (g)
c
Zn (s) + H2SO4 → ZnSO4 (aq) H2 (g)
d
Na2SO4 (aq) + BaCl2 (aq) → BaSO4 (s) + NaCl (aq)
e
Fe (s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s)
f
H2 (g) + O2 (g) → H2O (l)
g
HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
h
Al (s) + CuCl2 (aq) → AlCl3 (aq) + Cu(s)
6.
A student dropped few pieces of marble in dilute hydrochloric acid, contained in a test tube. The evolved gas was then passed through lime water. What change would be observed in lime water? What will happen if excess of gas is passed through lime water? Write balanced chemical equations for all the changes observed
7.
A grey coloured metal ‘X’ is used for coating iron to prevent it from rusting.’X’ when dipped in iron sulphate solution , the solution changes to colourless and a greyish black metal ‘Y’ is formed .Identify ‘X’ and ‘Y’ and the type of reaction.
8.
What change in color is observed when white silver chloride is left exposed to sunlight? State the type of chemical reaction in this change.
12
OR
Why do we store silver chloride in dark coloured bottles?
9.
A substance ‘X’ is pale green coloured solid. It gets oxidised to reddish brown coloured solid, if kept in air for long time. On heating it forms reddish brown solid ‘Y’ along with two pungent smelling gases ‘A’ and ‘B’. ’A’ is anhydride of sulphurous acid and ‘B’ when dissolved in water forms sulphuric acid. Identify ‘X’, ‘Y’, ‘A’ and ‘B’.Name the type of reaction.
10.
A light sensitive compound ‘X’ of silver is used in black and white photography. On exposure to sunlight its colour changes to gray :
a
Identify ‘X’.
b
Write a chemical equation to express the above change .
c
Identify the type of chemical reaction.
11.
What is an oxidation reaction? Identify in the following reaction:
(a) the substance oxidized and (b) the substance reduced
.(Delhi 2008)(sample paper 2011-12)
ZnO + C → Zn + CO
CuO + H2 → Cu + H2O
12.
A silver article generally turns black when kept in open for a few days. The article when rubbed with tooth paste again starts shining.
a
Why do silver articles turn black when kept in open for few days? Name the phenomenon involved.
13
b
Name the black substance formed and give its chemical formula.
13.
a
When the powder of a common metal is heated in an open china dish, its colour turns black. However, when hydrogen is passed over the hot black substance so formed, it regains its original colour. Based on the above information answer the following questions: (OD 2010)
What type of chemical reaction takes place in each of the two given steps?
b
Name the metal initially taken in the powder form. Write balanced chemical equations for both reactions.
OR
A brown substance 'X' on heating in air forms a substance 'Y'. When hydrogen gas is passed over heated 'Y', it again changes back into 'X'
a Name the substance X and Y.
b Name the chemical processes occurring during both the changes. Write the chemical equations
14.
Observe the given figure and answer the following questions(OD 2005)

a Write the complete balanced reaction for the above.
b
Type of reaction involved.
c Is there any precipitate formed?
d If any precipitate formed, write the colour of the precipitate.

SECTION D
1
The diagram shows three calcium compounds.
Step 3
CaO CaCO3
Step I Step 2
Ca(OH)2
a Which compound is present in lime water?
b What is added to calcium oxide to carry out step 1.
c Which step occurs during the test for carbon dioxide?
2 After ten minutes of keeping the set up as shown in the figure, the colour of the iron
nail changes, what does this indicate?

a. Name the type of chemical reaction that takes
place between copper sulphate and iron nail.
_______________________________________
b. Which of the two metals involved in the given
process is more reactive?
_______________________________________
c. What change do you expect in the reaction
mixture if a copper wire is kept immersed
in an iron sulphate solution?
_______________________________________
_______________________________________
3 Observe the test tube ‘A’ and ‘B’ in the diagram given below and answer the following
questions

a. In which test tube will the reaction take place?
________________________________________
b. Name the type of reaction and write a balanced
equation for the reaction.
________________________________________
________________________________________
________________________________________
15
3
Study the following set up and answer the following:

a.Write the name and the chemical formula of the product formed.
___________________________________________
___________________________________________
b. State the two observations made in the experiment.
___________________________________________
___________________________________________
___________________________________________
4
Study the following activity and identify the following:

a. Type of reaction.
__________________________________________
b. Name the gas evolved in the above reaction.
__________________________________________
c. Do you observe any colour change in the above reaction? If yes, mention the colour change.
__________________________________________
__________________________________________
d. Name the colored substance formed.
__________________________________________
__________________________________________
5
The given set up shows the electrolysis of water taking place.

a
Identify the gases evolved at cathode and anode.
16
b
Why is the gas collected in one of the test tubes double the amount in the other? Name this gas.
c
Test these gases one by one by bringing a burning candle close to the mouth of the test tubes. What happens in each case?
6
Observe the following picture and do as directed:

a
What are the two conversions explained by the research student? Show with the help of a chemical equation.
17
b
How can chemical industries reduce their carbon emission?
c
What are the values depicted by Bhaduri and Lidija Siller?
QUESTIONS BANK
1.
What are the endothermic reactions? (OD 2005 )
Give an example of an endothermic reaction.(sample paper 2010)
2.
Why do we apply paint on iron articles?
"Oxidation and reduction processes occur simultaneously." Justify this statement with the help of an example. .(sample paper 2010)
3.
(a)With the help of a suitable example, explain Oxidation and Reduction in terms of gain or loss of oxygen. (b)What is meant by rancidity ?(sample paper 2011-12)
4.
Which one is a chemical change - fermentation of fruit juice or diluting fruit juice ?
5. Write observation with reaction for the following: 2 granulated zinc reacts with dil. Sulphuric acid.
6.
What is the role of a catalyst in a chemical reaction? (OD 2007)
7.
What happens when sodium sulphate and barium chloride solutions are mixed?
(OD 2005)
8. “Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate”. (sample paper 2010)
(a) Translate the above statement into a chemical equation
(b) State two types in which this reaction can be classified.
9.
Complete the following reactions and balance them: (Delhi 2006 )
Zn + H2SO4 →
Fe (s) + H2O (g) →
C6H12O6 (aq) +O2 (aq) →
18
DRILL EXERCISE
1
Balance the following reactions and indicate which of the six types of chemical reaction are being represented:
a
____ NaBr + ____ Ca(OH)2  ___ CaBr2 + ____ NaOH
Type of reaction:
b
____ NH3+ ____ H2SO4  ____ (NH4)2SO4
Type of reaction:
c
____ CH4 + ____ O2  ____ CO2 + ____ H2O
Type of reaction:
d
____ Pb + ____ H3PO4  ____ H2 + ____ Pb3(PO4)2
Type of reaction:
e
____ Li3N + ____ NH4NO3  ___ LiNO3 + ___ (NH4)3N
Type of reaction:
f
____ HBr + ___ Al(OH)3  ___ H2O + ___ AlBr3
Type of reaction:
2
Balance the following equations. Also write word equations for the same.
a
K + H2O KOH + H2
Word equation
b
Ca(NO3)2 CaO + O2 + NO2
Word equation
c
Pb3O4 + HCI (conc.) PbCl2 + H2O + Cl2
Word equation
d
NaNO3 NaNO2 + O2
Word equation
e
NH3 + PbO Pb + N2 + H2O
Word equation
f.
NH3 + Cl2 NH4Cl + N2
Word equation
g
NH3 + O2 NO + H2O
19
Word equation
h
FeCl3 + NaOH Fe(OH)3 + NaCl
Word equation
i
FeO + O2 Fe2O3
Word equation
j
NO2 + O2 + H2O HNO3
Word equation
k
P2O5 + H2O H3PO4
Word equation
l
FeCl2 + Cl2 FeCl3
Word equation
m
CuO + CO Cu + CO2
Word equation
3
Write the word equations below as chemical equations and balance
a
Zinc and lead (II) nitrate react to form zinc nitrate and lead.
b
Aluminum bromide and chlorine gas react to form aluminum chloride and bromine gas.
c
Sodium phosphate and calcium chloride react to form calcium phosphate and sodium
chloride.
d
Potassium metal and chlorine gas combine to form potassium chloride.
e
Aluminum and hydrochloric acid react to form aluminum chloride and hydrogen gas.
f
Calcium hydroxide and phosphoric acid react to form calcium phosphate and water.
g
Copper and sulfuric acid react to form copper (II) sulfate and water and sulfur dioxide.
20
h Reaction between ammonium hydroxide and sulphuric acid producing ammonium
sulphate and water.
i The reaction of a metal carbonate with dilute sulphuric acid to produce carbon dioxide.
j Reaction of Magnesium with hydrochloric acid.
k Dissolution of calcium oxide in water.
l Formation of ammonia.
4 The following equations are based on synthesis or direct combination. Complete and
balance them
a Fe + Cl2 
b P2O5 + H2O 
c Fe + O2 
d N2 + H2 
e Cu + Cl2 
f Al + N2 
g K2O + H2O 
h SO2 + H2O 
i H2 + S 
j H2 + Cl2 
5
Give balanced equations for the action of heat on:
a Lead (II) nitrate :
______________________________________________________________________
b
Iron(II) sulphate
_____________________________________________________________________
21
c
Silver oxide
______________________________________________________________________
d
Magnesium carbonate
______________________________________________________________________
e
Lead iodide
______________________________________________________________________
f
Sodium nitrate
______________________________________________________________________
6
The following equations are based on displacement. Complete and balance the
following equations
a Zn + HCl 
b
KBr + Cl2 
c
Cu + AgNO3 
d
Mg + H2SO4 
e
CuSO4 + Fe 
f
Nal + Cl2 
g
KCl + F2 
h
K + H2O 
i
Zn + FeCl2 
j
K + Ca(NO3)2 
k
Pb + AgNO3 
22
l
Ca + HCl 
7 The following equations are based on double decomposition. Complete and balance the
flowing equations.
a
CuSO4 + NaO  ________ +
___________
b
Cu(OH)2 + ________  CuCl2 + ___________
c
________ + KOH  Fe(OH)2 + ___________
d
KOH + ________  KCl + ___________
e
CaCl2 + NaOH  _______ + __________
f
________ + ________  PbSO4 + __________
g
AgNO3 + HCl  _______ + _________
h
________ + _______  CaSO4 + H2O
i
ZnCl2 + _______  Zn(OH)2 + _________
LINKS:
 http://www.khanacademy.org/science/chemistry/v/balancing-chemical-equations
 http://www.youtube.com/watch?v=Ym1ln3LG46k&feature=relmfu
 http://www.youtube.com/watch?v=Teaexn1luBA&feature=relmfu
 http://www.youtube.com/watch?v=yuStJotow2I&NR=1&feature=fvwp
 https://docs.google.com/present/edit?id=0AcLTInP8Zbs6ZGRqY2dycTlfNzRkdDd3Z
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