CHEMISTRY PRACTICAL
CLASS – X
1.Finding the pH of the following samples by using pH paper/universal
indicator :
Objective:
Finding the pH of the following samples by using pH paper / universal indicator
a.) Dilute Hydrochloric Acid
b.) Dilute NaOH solution.
c.) Dilute Ethanoic Acid Solution
d.) Lemon Juice
e.) Water
f.) Dilute Sodium Hydrogen Carbonate solution.
Fundamentals:
*pH of a solution is defined as the negative logarithm of the hydrogen ion
concentration in moles per litre
pH = - Log 10 [ H+]
since H+ ion is associated with H2O molecules and therefore we normally write H+
as H3O and pH is written as
pH= - log 10 [H3O+]
Apparatus Required:
Test tube, test tube stand, dropper, pH paper strips, and given samples whose pH
is to be determined.
Observation:
S.No. Given Sample Observe pH Nature of the
d Colour value given sample
on pH
paper
A Dilute hydrochloric Acid Acidic
B Dilute NaOH solution Alkaline
c. Dilute Ethanoic Acid solution Acidic
d. Lemon Water Acidic
e. Water Neutral
d. Dilute Sodium Hydrogen Carbonate Alkaline
Solution
Result:
pH values of the given samples are as shown in the table above.
pH value of water is 7, hence it is neutral.
pH values of the samples of dilute hydrochloric acid, dilute solution of
Ethanoic acid, and lemon juice are less than 7, hence they are acidic in
nature.
pH values of the samples of dilute NaOH solution and dilute sodium
hydrogen carbonate solution are greater than 7 hence they are alkaline in
nature.
Precautions:
*Test tube to be used in the experiment should be washed thproughly using
distilled water.
*Separate droppers should be used for each sample or the dropper should be
washed thoroughly with distilled water before being used for the next sample.
*pH paper used should be of standard quality.
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Experiment - 2
Objective:
Studying the properties of Acids and Bases by their reaction with:
a.)Litmus solution
b.) Zinc metal
c.)Solid sodium carbonate
Fundamentals :
Acids are substance that produce hydrogen ions (H+) when mixed with water
.For example, HCl when dissolved in water gives out H+ ions and Cl- ions.
HCl (aq) →H+ (aq) + Cl- (aq)
Bases are substances that produce hydroxyl ions (OH -) when mixed with
water. For example NaOH when dissolved in water gives out OH - ions and
Na+
Sodium hydroxide does not react with sodium carbonate.
Apparatus / Materials required:
Test tubes, Iron stand, distilled water, Hydrochloric acid , Sodium hydroxide
solution, Zinc metal pieces , sodium carbonate, litmus solutions, lime water, match
stick, splinter, a cork fitted with a delivery tube etc.
Precaution:
All the apparatus employed in the experiment such as glass test tube, beakers, glass
rods etc should be washed with distilled water before starting the experiment.
Experiment :3 A
Objectives:
Performing and observing the following reactions and classifying them into:
a.) Combination reaction
b.) Decomposition reaction
c.) Displacement reaction
d.) Double displacement reaction
i) Action of water on quick lime
ii) Action of heat on ferrous sulphate crystals
iii) Iron nails kept in copper sulphate solution.
iv) Reaction between sodium sulphate and barium chloride solutions.
Fundamentals:
i) Action of water on quick lime
*Quick lime or Calcium Oxide is a white amorphous and porous solid
which is highly stable.
*When heated strongly it emits an intensive white light called lime light.
*it reacts vigorously with water to produce slaked lime releasing a large
amount of heat. Thus the reaction of quick lime with water is highly
exothermic.
Cao + H2O → Ca(OH)2 + heat
*This reaction is a combination reaction.
ii.) Action of heat on ferrous sulphate crystals
Ferrous sulphate is green crystalline salt.
When heated in a test tube, it decomposes to give ferric oxide, sulphur
dioxide and sulphur trioxide with a characteristic odour of burning sulphur.
2FeSO4 → Fe2O3 + SO2↑ + SO3↑
iii) Iron nails kept in copper sulphate solution:
Fe + Cu2+So2- →Fe2+So2- + Cu
iv) Reaction between sodium sulphate and Barium chloride solution.
Na2SO4 + BaCl2 → BaSO4 + 2Nacl
This reaction is a double displacement reaction.
PART-I
Apparatus / material required:
Quick lime, Ferrous sulphate, Iron nails , Copper sulphate solution , sodium
sulphate solution, barium chloride solution, test tube, beakers , Iron stand, glass
rod, burner, water etc.
Observation and conclusion:
* When water is added to solid quick lime steam comes out with a hissing
sound and the solid swells up and finally crumbles to a powder.
* A large amount of heat is released during the reaction, thereby increasing the
temperature of the beaker significantly.
* The reaction which takes place is
CaO + H20 → Ca(OH)2 + heat
* This is a combination reaction. Here Calcium oxide and water combine to
form a single product, calcium hydroxide.
PART – II
Observation and conclusion:
The reaction which takes place is
2 FeSo4 ∆→ Fe2O3 + So2 ↑ + So3↑
*This is a decomposition reaction. Ferrous sulphate decomposes to form ferric
oxide along with evolution of sulphur dioxide and sulphur trioxide gases.
*On heating the green colour of ferrous sulphate crystals changes and then on
decomposition thus fom a reddish brown coloured powder of ferric oxide.
PART – III
Observation and Conclusion:
The reaction which takes place is :
Fe + CuSO4 → FeSO4 + Cu
This is a displacement reaction .Iron being more reactive then copper
displaces copper from copper sulphate solution.
Thus, Iron nails turn from grey to brown in colour and the copper sulphate
solution changes colour from blue to light green.
PART – IV:
Observation and Conclusion:
The reaction which takes place is
Na2SO4 +BaCl2 → BaSO4 +2NaCl
This is a double displacement reaction. Here SO4 ions displace Cl- ions and Cl-ions
displaces SO4 ions
Thus a white precipitate of barium sulphate is formed which settles down at the
bottom of the beaker.
Precautions:
Test tube, beaker etc. should be clean and dry.
For heating purpose always hard glass test tubes should be used.
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Experiment :3B
Objective:
Observing the action of Zn,Fe,Cu and Al metals on the following salt solutions
a.)ZnSo4
b.)FeSo4
c.)CuSo4
d.)Al, (So4)3
Arranging Zn, Fe, Cu and Al in the decreasing order of reactivity based on the
above result.
Fundamentals:
All metals are not equally reactive. Some metals are more reactive than others.
The metals which can lose electrons more readily to form positive ions are more
reactive. The less reactive metals do not lose electrons easily.
Activity Series: Relative Reactivities of Metals
K Potassium Most Reactive
Na Sodium ”
Ca Calcium ”
Mg Magnesium ”
Al Aluminium ”
Zn Zinc ”
Fe Iron ”
Pb Lead Reactivity
decreases
H Hydrogen ”
Cu Copper ”
Hg Mercury ”
Ag Silver ”
Au Gold Least Reactive
Apparatus Required:
Thin and clean strips of Zinc, Iron, copper and Aluminium metals, aqueous
solutions of ZnSo4, FeSo4, CuSo4 and Al2(So4)3, a set of about 20 clean test tubes,
distilled water, filter paper, etc.
Result:
* Observe from experiments at S.No 7, 8 and 9 that copper is less reactive
than zinc as well as iron and aluminium. So we may conclude that among the
given 4 metals, Copper is least reactive.
* Observe from experiments at S.no10, 11 and 12 that aluminium is more
reactive than zinc as well as iron and copper. So we may conclude that among the
given 4 metals,
Aluminium is most reactive.
Observe from experiment at S.No.1, 2, and 3 that zinc is less reactive than
aluminium, but more reactive than iron and copper.
Observe from experiment at S.No. 4, 5, 6 that iron is less reactive than aluminium
and zinc but more reactive than copper.
From the above, we can arrange Zn, Fe, Cu and Al metals in the decreasing order
of reactivity as follows:
Al> Zn > Fe> Cu.
Precautions:
* The glass test tubes employed in the experiment, should be washed with
distilled water before starting the experiment.
*The test tubes should be suspended with the help of iron stand or in a test tube
stand.
*8-10 aqueous solutions of metal salts should be employed for performing the
chemical reactions.
Experiment: 4
Objective:
Study of the comparative cleaning capacity of a sample of a sample of soap in soft
and hard water.
Fundamentals:
*Natural water is said to be hard when it does not readily form lather with soap.
*Hard water contains dissolved calcium and magnesium salts.
*Water is said to be soft ,if it readily forms lather with soap, soft water is free
from dissolved calcium and magnesium salts.
Apparatus/ materials required:
Soap sample, sample of hard and soft water, distilled water, a glass beaker, test
tubes, corks ,wire gauge, tripod stand, glass rod, burner and a stop watch.
Observation:
S.No. Test Tube Time taken for disappearance of foam
1. A
2. B
Observe that the amount of foam produced in test tube B is much more
than that produced in test tube A,and thus the time taken for disappearance
of foam in case of test tube B is more than the time taken in case of test
tube A.
Result :
From the above observation it can be concluded that the foaming capacity of the
given sample of soap in more than in hard water or we may say the cleaning
capacity of soap in soft water is more as compared to hard water.
Precaution:
*Both the test tubes should be shaken in a similar manner and for the number of
times.
*An equal amount of the sample of hard and soft water should be taken in test
tubes A and B.
*An equal amount of the prepared soap solution should be added to each of the test
tubes A and B.
*Time taken for disappearance of foam should be measured accurately.
