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1
Q

What is pH?

A

power of hydrogen is a measure of concentration ion in a solution.

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2
Q

what is Kw?

A

Kw (ionization constant) is the measure of strength of acid or base

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3
Q

If a pH of a solution is 5.5. What will be its POH

A

pH+POH=14 ______POH=14 - 5.5________POH=8.5

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4
Q

why are antacids used in acidity of a stomach?

A

they neutralize the acid in the stomach to relieve indigestion

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5
Q

what is the advantage of finding pH of a soil?

A

having an optimum pH is important for plants to grow and for energy

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6
Q

what is the pH of a human blood?

A

it ranges between 7.35—7.45

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7
Q

name some natural substances that behave like bases ?

A

NaOH, CaCO3, KOH, Ca(OH2), Mg(OH2), LiOH

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8
Q

what are indicators

A

substances whose solution color changes when pH is changed eg. phenolphthalein

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9
Q

what is a standard solution

A

solution whose concentration is precisely known

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10
Q

some strings are basic e.g. nettle strings and wasp strings. They contain basic substance histamine. How will you treat a person beaten by a wasp

A

First we will wash the infected region by the soap and then we will treat with a week dilute acid sucha s vinegar

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11
Q

why sodium hydroxide solution cannot be used as a primary standard.

A

NaOH being a strong base, reacts with atmosphere CO2 to form NaCO3 this disturbs its purity {NaOH is not stable}

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12
Q

what color does phenolphthalein give at the end of chemical reaction

A

pink——-»> purple

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13
Q

write a balanced chemical equation for the reaction that takes place during the standardization of sodium hydroxide

A

NaOH + HCL———-> NaCL + H2O

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14
Q

what does strength of a solution means?

A

amount of solute (in g) dissolved per litre of a solution

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15
Q

what is primary solution? Give some examples of primary standards?

A

reagent that is extremely pure and stable, no water of hydration and have high molecular weight e.g. NaCL, Zinc, KBrO3

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16
Q

why should the lower meniscus of the colorless liquid noted while taking reading?

A

the reading is accurate when we observe reading from lower meniscus

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17
Q

why sodium hydroxide has corrosive action on the skin?

A

NaOH is a strong alkaline and can burn skin as skin is very delicate, thin and light

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18
Q

how many molecules are present as the water of crystallization in oxalic acid?

A

2

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19
Q

differentiate between strong acid and weak acid

A

STRONG ACID
-ionizes completely in aqueous solution
-strongly corrosive

WEAK ACID
-ionizes partially in aqueous solution
-less corrosive

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20
Q

why is an indicator used in titration?

A

to find out the point of equivalence when a particular solution have reached the point of neutralization

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21
Q

what is meant by titration?

A

a technique where standard solution of known concentration is used to determine the concentration of unknown solution

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22
Q

what is common name of sodium hydroxide?

A

caustic soda

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23
Q

write a balanced chemical equation for the reaction that takes place during standardization of oxalic acid?

A

C2H204 + 2NaOH——-> Na2C2O4+ 2H20

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24
Q

a mixture is prepared by adding MnO2 and concentrated H2SO4 to the salt solution. Why do we heat the mixture after adding concentrated H2SO4 to it?

A

heating the mixture would increase the rate of reaction of oxidation, heat also causes the H2SO4 to become more concentrated through evaporation of water.

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25
why are chlorine bromine and iodine placed in the same group of the periodic table?
They all have 7 electron in their valence shell
26
which element of the halogen family exists in the liquid state and solid state?
Bromine is the liquid Iodine is the solid
27
what is the difference between CL and CL2
CL- -its chlorine atom -its an ion -it does not exist naturally CL2 - it's a chlorine gas -its a molecule - it exists naturally
28
how is Halide ion formed from halogen atom
the halogen atom gains electron to form halide atom
29
which element of halogen does not exist naturally
ASTATINE and TENNESSINE
30
which halogen is radioactive
ASTATINE
31
why concentrated sulphuric acid causes severe burn
concentrated H2SO4 is an extremely strong acid when it comes in contact with our skin it cause chemical burns through process known as tissue destruction.
32
name the acid used in the flame test?
HCL because its more volatile in the nature
33
why is the platinum wire preferred over copper wire to do the flame test?
platinum wire is heat resistant, we can also use heat resistant glass rod.
34
how is platinum wire cleaned before performing the flame test for each salt
put HCL on the platinum wire and heat it, if flame is colorless, it is cleaned
35
how does the use of concentrated HCL acid helps in the detection of different radicals through the flame test
HCL facilitates displacement reaction
36
what is the purpose of using blue glass in the flame test
it is used as a confirmatory test
37
what are damaging effects of vapour of concentrated HCL?
HCL is corrosive if we inhale the vapours of HCL it will damage our organs
38
do ketones give positive test with Fehlings and Tollens reagent?
no because ketones don't have free aldehydes groups that can be oxidized to carboxylic acid which can be detected by change in color.
39
can you use 2,4DNPH regents to test sugar in the urine of a diabetic patient?
yes it can be used to test for the presence of reducing sugar such as glucose.
40
give a few characteristic properties of 2,4 dinitrophenyl hydrazine
yellow or orange in color, insoluble in water, soluble in organic solvent such as ethanol,polar compound , organic compound
41
what is the formula for 2,4 dinitrophenyl hydrazine
C6H6N4O4
42
what is the formula for fructose
C6H12O6
43
a fructose is aldehyde or ketone
fructose is ketone
44
what is the color of precipitate when fructose reacts with 2,4 dinitrophenyl hydrazine
orange or yellow precipitate is formed
45
what is functional group
a functional group is a specific group of data that are responsible for characteristics chemical and physical properties of compound
46
what functional group present in pentanol
alcohol
47
name the chemicals used in tollens reagent
solution of silver nitrate (AgNO3) and ammonia (NH3)
48
what is the composition of the fehlings solution
Fehling A=solution of copper sulphate Fehling B= solution of NaO and rouchelle salt KNaC4H4O6 . H20
49
what is the function of Rochelle salt in fehling solution
Rochelle salt stabilizes and dissolve copper ion , prevents the formation of of cupric hydroxide and allows for accurate detection for reducing sugar
50
what is more reactive aldehyde or ketones
aldehyde are generally more reactive due to the presence of hydrogen atom of carboxylic group which allows electron deficient compounds to make bond with it
51
define lime water test
we use lime water test to detect the pressure of CO2 gas
52
what is the general formula for oxalic acid
H2C204
53
which carboxylic acid is responsible for odour and taste of vinegar
vinegar is dilute solution of acetic acid. Its odour and taste is due to the acetic taste in it
54
what are the products when carboxylic acid reacts with bicarbonates
metal carboxylate , carbon dioxide gas and water. When the sodium bicarbonates reacts with acetic acid, sodium acetate, CO2 and water is formed .
55
where does carbon dioxide comes from
from bicarbonates
56
which to functional group are joined together to give carboxylic acid group.
1) carboxyl group 2) hydroxyl group
57
name some commonly used carboxylic acid
1) acetic acid 2)oxalic acid 3)succinic acid
58
while the preparing the cakes and cookies, Why the flour swells up with the addition of baking soda in it
it swells up due to evolution of carbon dioxide gas
59
write down the observation of the reaction of the carboxylic acid with ferric chloride and sulphuric acid
2FeCl3 + 2H2C2O4 + 2H2SO4-------------------->2FeO4S + 6HCL + 2CO2
60
why does phenol gives ferric chloride test
phenol reacts with FeCl2 to form a colored, complex, FERRIC PHENOXIDE. The OH of the phenol donate the electron pair to ferric ion in in FeCl3
61
what is resonance
it is a way of describing delocalized electron with contain formula where bonds cant be represented by lewis formula
62
why is phenol aromatic in nature
because it contains benzene ring
63
what is other name of phenol
phenolic
64
which functional group is present in ethanoic acid
carboxylic acid
65
name at least two chemical test other than potassium permanganate test, used for detection of unsaturation in organic compound
bromine water test iodine test
66
which functional group is present in propylene
ALKENE
67
why desi ghee is formed in semi solid form
because it saturated hydrocarbon (saturated are solid in room temprature)
68
what's the difference between saturated and unsaturated hydrocarbon
SATURATED -solid in shape at room temp -only single bond UNSATURATED -liquid in shape at room temp -have double or triple bond
69
how hydrogenation of liquid oil takes place
H2 is added reacted with veg oil under 180 degree temp produces margarine
70
is burning of sugar chemical change
yes due to the formation of CO2 and H2O
71
define the composition reaction. Name the product obtained by decomposition reaction
a simple compound breaks into more simpler substances.
72
what is caramel and where it is used
caramel is the result of heating sugar at high temp, used in food and beverage for topping
73
by heating natural gas at high temperature in the absence of the air. it breaks into carbon and hydrogen which is used either as fuel or the production of ammonia. What is chemical name for it and write down its balanced chemical equation
steam reforming of natural gas CH4 + H20-------------->> CO + 3H2
74
define hard water
water will bicarbonate of Mg ,Ca and chloride and sulfate
75
what is the reason for the permanent hardness water
due to the presence of chloride and sulfate of Mg and Ca
76
describe the disadvantages of hard water
it doesn't fulfill our thirst, if drink oftenly can cause kidney stones, it doesn't produce lather, so it can utilize more soap.
77
is hard water good for drinking
No hard water is not good for drinking
78
name reagent used to remove permanent hardness of water
NaCO3-------------->>Sodium carbonate
79
how will you remove temporary hardness of water
by boiling so that bicarbonate can decompose using Clarks method
80
a sample of water was found to contain calcium bicarbonate , what kind of carbonate it have
permanent hardness
81
can we remove permanent hardness of water by distillation
yes
82
write the main source of water pollution
industrial waste, sewage temporary hardness is due to presence of bicarbonates

Chemistry Practical (1 decks)

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