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chemistry Flashcards

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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
Q

why are chlorine bromine and iodine placed in the same group of the periodic table?

A

They all have 7 electron in their valence shell

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26
Q

which element of the halogen family exists in the liquid state and solid state?

A

Bromine is the liquid
Iodine is the solid

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27
Q

what is the difference between CL and CL2

A

CL-
-its chlorine atom
-its an ion
-it does not exist naturally

CL2
- it’s a chlorine gas
-its a molecule
- it exists naturally

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28
Q

how is Halide ion formed from halogen atom

A

the halogen atom gains electron to form halide atom

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29
Q

which element of halogen does not exist naturally

A

ASTATINE and TENNESSINE

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30
Q

which halogen is radioactive

A

ASTATINE

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31
Q

why concentrated sulphuric acid causes severe burn

A

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.

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32
Q

name the acid used in the flame test?

A

HCL because its more volatile in the nature

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33
Q

why is the platinum wire preferred over copper wire to do the flame test?

A

platinum wire is heat resistant, we can also use heat resistant glass rod.

34
Q

how is platinum wire cleaned before performing the flame test for each salt

A

put HCL on the platinum wire and heat it, if flame is colorless, it is cleaned

35
Q

how does the use of concentrated HCL acid helps in the detection of different radicals through the flame test

A

HCL facilitates displacement reaction

36
Q

what is the purpose of using blue glass in the flame test

A

it is used as a confirmatory test

37
Q

what are damaging effects of vapour of concentrated HCL?

A

HCL is corrosive if we inhale the vapours of HCL it will damage our organs

38
Q

do ketones give positive test with Fehlings and Tollens reagent?

A

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
Q

can you use 2,4DNPH regents to test sugar in the urine of a diabetic patient?

A

yes it can be used to test for the presence of reducing sugar such as glucose.

40
Q

give a few characteristic properties of 2,4 dinitrophenyl hydrazine

A

yellow or orange in color, insoluble in water, soluble in organic solvent such as ethanol,polar compound , organic compound

41
Q

what is the formula for 2,4 dinitrophenyl hydrazine

A

C6H6N4O4

42
Q

what is the formula for fructose

A

C6H12O6

43
Q

a fructose is aldehyde or ketone

A

fructose is ketone

44
Q

what is the color of precipitate when fructose reacts with 2,4 dinitrophenyl hydrazine

A

orange or yellow precipitate is formed

45
Q

what is functional group

A

a functional group is a specific group of data that are responsible for characteristics chemical and physical properties of compound

46
Q

what functional group present in pentanol

A

alcohol

47
Q

name the chemicals used in tollens reagent

A

solution of silver nitrate (AgNO3) and ammonia (NH3)

48
Q

what is the composition of the fehlings solution

A

Fehling A=solution of copper sulphate
Fehling B= solution of NaO and rouchelle salt KNaC4H4O6 . H20

49
Q

what is the function of Rochelle salt in fehling solution

A

Rochelle salt stabilizes and dissolve copper ion , prevents the formation of of cupric hydroxide and allows for accurate detection for reducing sugar

50
Q

what is more reactive aldehyde or ketones

A

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
Q

define lime water test

A

we use lime water test to detect the pressure of CO2 gas

52
Q

what is the general formula for oxalic acid

A

H2C204

53
Q

which carboxylic acid is responsible for odour and taste of vinegar

A

vinegar is dilute solution of acetic acid. Its odour and taste is due to the acetic taste in it

54
Q

what are the products when carboxylic acid reacts with bicarbonates

A

metal carboxylate , carbon dioxide gas and water. When the sodium bicarbonates reacts with acetic acid, sodium acetate, CO2 and water is formed .

55
Q

where does carbon dioxide comes from

A

from bicarbonates

56
Q

which to functional group are joined together to give carboxylic acid group.

A

1) carboxyl group
2) hydroxyl group

57
Q

name some commonly used carboxylic acid

A

1) acetic acid
2)oxalic acid
3)succinic acid

58
Q

while the preparing the cakes and cookies, Why the flour swells up with the addition of baking soda in it

A

it swells up due to evolution of carbon dioxide gas

59
Q

write down the observation of the reaction of the carboxylic acid with ferric chloride and sulphuric acid

A

2FeCl3 + 2H2C2O4 + 2H2SO4——————–>2FeO4S + 6HCL + 2CO2

60
Q

why does phenol gives ferric chloride test

A

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
Q

what is resonance

A

it is a way of describing delocalized electron with contain formula where bonds cant be represented by lewis formula

62
Q

why is phenol aromatic in nature

A

because it contains benzene ring

63
Q

what is other name of phenol

A

phenolic

64
Q

which functional group is present in ethanoic acid

A

carboxylic acid

65
Q

name at least two chemical test other than potassium permanganate test, used for detection of unsaturation in organic compound

A

bromine water test
iodine test

66
Q

which functional group is present in propylene

A

ALKENE

67
Q

why desi ghee is formed in semi solid form

A

because it saturated hydrocarbon (saturated are solid in room temprature)

68
Q

what’s the difference between saturated and unsaturated hydrocarbon

A

SATURATED
-solid in shape at room temp
-only single bond
UNSATURATED
-liquid in shape at room temp
-have double or triple bond

69
Q

how hydrogenation of liquid oil takes place

A

H2 is added reacted with veg oil under 180 degree temp produces margarine

70
Q

is burning of sugar chemical change

A

yes due to the formation of CO2 and H2O

71
Q

define the composition reaction. Name the product obtained by decomposition reaction

A

a simple compound breaks into more simpler substances.

72
Q

what is caramel and where it is used

A

caramel is the result of heating sugar at high temp, used in food and beverage for topping

73
Q

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

A

steam reforming of natural gas

CH4 + H20————–» CO + 3H2

74
Q

define hard water

A

water will bicarbonate of Mg ,Ca and chloride and sulfate

75
Q

what is the reason for the permanent hardness water

A

due to the presence of chloride and sulfate of Mg and Ca

76
Q

describe the disadvantages of hard water

A

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
Q

is hard water good for drinking

A

No hard water is not good for drinking

78
Q

name reagent used to remove permanent hardness of water

A

NaCO3————–»Sodium carbonate

79
Q

how will you remove temporary hardness of water

A

by boiling so that bicarbonate can decompose using Clarks method

80
Q

a sample of water was found to contain calcium bicarbonate , what kind of carbonate it have

A

permanent hardness

81
Q

can we remove permanent hardness of water by distillation

A

yes

82
Q

write the main source of water pollution

A

industrial waste, sewage

temporary hardness is due to presence of bicarbonates

Chemistry Practical (1 decks)

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