CHAPTER: 2
IS MATTER AROUND US PURE
Q. Which
separation technique will you apply for the separation of the separation of the
following?
a) Sodium
chloride from its solution in water
Answer. Evaporation
b) Ammonium chloride
from a mixture containing sodium chloride and ammonium chloride.
Answer. Sublimation
c) Small piece of
metal in the engine oil of a car.
Answer. Filtration
d) Different
pigment from an extract of flower petal.
Answer. Chromatography
e) Butter from
curd.
Answer. Centrifugation
f) Oil from
water.
Answer. Separation funnel
g) Tea leaves
from tea.
Answer. Filtration
h) Iron pins from
sand.
Answer. Magnetic separation
i) Wheat grains
from husk.
Answer. Sedimentation
j) Fine mud
particle suspended in water.
Answer. Filtration
Q2 .Write the
steps you use for making tea. Use the words solution, solvent, solute, dissolve,
soluble, insoluble, filtrate and residue.
Answer.1) Take a cup of
water in a container as solvent and heat it.
2) Add sugar in it which is
solute .Heat it till all sugar dissolves.
3) You get a solution of water and sugar.
4) Sugar is soluble in
water completely.
5) Add half a tea spoon of
tea leaves it is in soluble in water.
6) Boil the content and add
milk which is also soluble in water boil again.
7) Filter the tea with the
help of strainer, the tea collected, in cup is filtrate and the tea leaves are
collected on the strainer is residue.
Q3. Pragya tested
the solubility of three different substances at different temperature and
collected the data as given below ( results are given in the following table as
grams of substance dissolved in 100 g of water to form, a saturated solutions).
|
SUBSTANCE DISSOLVED
|
TEMPERATURE IN K AND SOLUBLITY
|
|||||
|
283
|
293
|
313
|
333
|
353
|
||
|
Potassium nitrate
|
21
|
32
|
62
|
106
|
167
|
|
|
Sodium chloride
|
36
|
36
|
36
|
37
|
37
|
|
|
Potassium chloride
|
35
|
35
|
40
|
46
|
54
|
|
|
Ammonium chloride
|
24
|
37
|
41
|
55
|
36
|
|
a) What
mass of potassium nitrate would be needed to produce a saturated solution of
potassium nitrate in 50g of water at 313 k?
b) Pragya
makes a saturated solution of potassium chloride in water at 353 k and leaves
the solution to cool at the room temperature
c) What
would she observes the solution cools? Explain.
d) Find
the solubility of each salt at 298 k which salt has the highest solubility at
this temperature
e) What is
the effect of change f temperature on the solubility of a salt?
Answer. A) Mass of
KNO3to produces a saturated solution of KNO3 in 100 g of water 313 k =62g
Therefore mass of
KNO3 in 50 g of water at 313k
= 62.0(50)
=31.0g
100
b) Crystals of
potassium chloride will be obtained on cooling the saturated solution.
c) Solubility of ach
salt at 293 k is
Potassium nitrate
-32g
Sodium chloride -36
g
Potassium chloride -
35g
Ammonium chloride –
37 g
d) On increasing the
temperature, solubility of a salt increases.
Q4.
Explain the following giving examples
a)
Saturated solution
b)
Pure
substance
c)
Colloid
d)
Suspension
Answer
a) Saturated solution:
In a given solvent when no more solute can dissolve further at the given temperature is called saturated
solution
b) Pure substance: A pure substance consists of a single
type of particle. E.g. gold and silver
c) Colloid: A colloid is a solution in which the size of
the solute particle are bigger than cannot be seen with our naked eyes they are
stabled. E.g. ink, blood
d) Suspension: It is a heterogeneous mixture in which the solute
particle is big enough to settle down. E.g. Chalk –Water, paints etc.
Q5. Classify each of the following
as a homogenous or heterogeneous mixture: Soda water, wood, air, soil, vinegar,
filtered tea
Answer:
Homogenous: Soda water, vinegar, filtered
tea
Heterogeneous: Wood, Air, and Soil
Q6. How would you confirm that a colourless
liquid given to you is pure water?
Answer: By finding the boiling point of a
given colourles liquid is the liquid boils at 100 c at atmospheric pressure, and
then it is pure water. This is because pure substance has fixed melting and
boiling point.
Q7. Which of the following
materials fall in the category of a pure substance?
a) Ice b)
milk
c) Iron
d) Hydrochloric acid
e) Calcium oxide f)
Mercury
G) Brick
h) Wood
i) Air
Answer. Pure substances are
Ice, Iron, Hydrologic acid, calcium oxide and mercury.
Q8.Identify the solutions
among the following mixtures
a)
Soil
b)
Air
c)
Water
d)
Coal
e)
Soda water
Answer. Solutions are:
sea water, soda water and Air
Q9. Which of the following will show tyndall effect”?
a)
Salt solution
b)
Milk
c)
copper
sulphate solution
d) Starch solution
Answer. Milk and
starch solution
Q10.
Classify the following into elements compound and mixture
a)
Sodium
b)
Soil
c)
Sugar solution
d)
Silver
e)
Calcium carbonate
f)
Tin
g)
Silicon
h)
Coal
i)
Air
j)
Soap
k)
Methane
l)
Carbon dioxide
m)
Blood
Answer.
Elements compound Mixture
Sodium Calcium carbonates Sugar solution
Silver methane Soil
Tin carbon dioxide Coal
Silicon Soap Air
Blood
Q11. Which of the following are
the chemical changes?
a)
Growth of
a plant
b)
Rusting of
iron
c)
Mixing f
iron trilling
d)
Cooking of
food
e)
Digestion of
food
f)
Freezing f
water
g)
Burning of
candle
Answer. Chemical changes are:
a) Growth of a plant
b) Rusting of iron
c) Coking of food
d) Digestion f food
e) Burning of candle
No comments:
Post a Comment
Note: only a member of this blog may post a comment.