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Chemistry Aakash > some basic concepts of chemistry > Flashcards

some basic concepts of chemistry Flashcards

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1
Q

define science

A

a continuing human effort to systemize knowledge for describing and understanding nature

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2
Q

define chemistry

A

branch of science that deals with composition, properties and interaction of matter

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3
Q

chemicals that cause acid rain

A

oxides of sulphur and nitrogen

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4
Q

greenhouse gases cause?

A

extreme weather events like drought, flooding, high wind and storm

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5
Q

what chemical compound in the brain acts as a messenger compound in the transmission of brain waves and in immune system slows down growth of tumor cells

A

nitric oxide

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6
Q

examples of chemical fertilisers that help in production of crops

A

urea, ammonium sulphate

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7
Q

____ , ____ , ____ & ____ are important in synthesis of various chemical compounds and products of commercial value

A

Alkalis, acids, salts and dyes

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8
Q

used for better preservation of food and check its wastage

A

sodium benzoate, and sodium metabisulphate

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9
Q

helpful for crop protection and storage of food grains

A

insecticides and pesticides like DDT , gammexane etc

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10
Q

outcomes of chemical synthesis

A

products of domestic consumptions like soaps, cosmetics, oils , perfumes etc

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11
Q

air conditioner uses

A

liquid ammonia or liquid sulphur dioxide

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12
Q

used in cancer therapy

A

cisplatin and taxol

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13
Q

used for helping AIDS victim

A

AZT - azidothymidine

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14
Q

with advancement in chemistry it is now possible to make new materials with specific _____,_____, and ____ properties
give examples

A

magnetic, electric and optical

  1. superconducting ceramics
  2. conducting polymers
  3. optical fibres
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15
Q

the ceramics used to make superconductors are a class of materials called

A

perovskites

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16
Q

conducting polymers

A

organic polymers that conduct electricity

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17
Q

properties of optical fibre

A
  • flexible,
  • transparent
  • made of pure glass
  • not much wider than human hair
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18
Q

pure glass is

A

silica

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19
Q

cause of environmental degradation like the ozone depletion

A

CFCs ( chlorofluorocarbon)

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20
Q

what is CFC

A

a refrigerant responsible for ozone depletion in the stratosphere

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21
Q

replacing cfcs??

A

newly synthesized blend of various compounds like R-410A and natural refrigerants like

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22
Q

natural refrigerants eg

A

ammonia, carbon dioxide and nonhalogenated hydrocarbons

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23
Q

non halogenated hydrocarbons….

A

preserve ozone layer and have no ammonia or only a low carbon dioxide, hydrocarbon

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24
Q

green house gases eg

A

methane, carbon dioxide

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25
Q

chemical reactions in living organisms are called

A

biochemical processes

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26
Q

what is matter?

A

anything that occupies space , has mass and can be felt with one or more of our senses

27
Q

two major classification of matter

A

physical and chemical properties

28
Q

physical states of matter can be classifies into

A

solid, liquid and gas

29
Q

solid

A
  1. tightly packed; not much freedom to move
  2. regular pattern, in a lattice
  3. not easily compressed
  4. fixed volume and shape
30
Q

liquid

A
  1. constituent particles are close together
  2. no regular arrangement
  3. takes shape of container
  4. particles can move; flow easily
  5. not easily compressed
  6. definite volume but not definite shape
31
Q

gas

A
  1. far apart
  2. no regular arrangement
  3. occupies shape and volume of its container
  4. move around ; flow easily
  5. compressible
  6. no definite shape and volume
32
Q

solid, liquid and gaseous states of matter are interconvertible by changing ?

A

temperature and pressure

33
Q

on applying pressure at a particular temperature gases can be liquefied for example

A

compress natural gas and petroleum gas which are used as CNG & LPG

34
Q

chemical classification

A

mixtures and pure substances

35
Q

what are mixtures?

- composition?

A

made up of two or more substances (its components)

- possess variable composition

36
Q

mixtures are divided into two

A

homogenous and heterogenous

37
Q

homogenous mixtures are

  • also called?
  • examples
A

mixtures which have the same composition throughout
- also called solutions
sugar solution, salt solution, air gasoline, brass etc

38
Q

heterogenous mixtures are

  • observed by
  • why
A

mixtures that do not have a uniform composition throughout

  • the different composition can be observed with the naked eye or with help of microscope
  • do not evenly mix and can be seen as separate entities
39
Q

examples of heterogenous mixtures?

A

salt and sugar mixture, grains and pulses + stone pieces, MILK, sand + iron fillings, sand + water etc

40
Q

components of a mixture can be separated by ____

like

A

physical methods
filtration, crystallisation, sublimation, extraction, distillation, chromatography , magnetic separation, simple hand picking etc

41
Q

what are pure substances ?

- properties

A

have a fixed composition and their constituents cannot be separated by simple physical methods
- properties do not vary

42
Q

pure substances are classified into

A

compounds and elements

43
Q

what is an element?

eg

A

pure substance that is made up of one kind of particle called atoms of molecules
silver, copper, sodium etc

44
Q

atoms of different elements are different in nature due to different number of ____, ____ & ____
lead to _______

A

protons electrons and neutrons

different properties

45
Q

some elements are _____ while others are _____ or _____

A

monoatomic

diatomic or polyatomic

46
Q

egs of diatomic molecules

A

H2, O2, N2, F2, Cl2 etc

47
Q

what is a compound?

A

when two or more atoms of different elements combine in a fixed proportion by mass , then a molecule of a compound is formed

48
Q

example of H2O chemically combined in a fixed proportion of

A

1:8 by mass

49
Q

example of compound CO2 chemically combined in a fixed proportion of

A

3:8 by mass

50
Q

general characteristic of a particular compound

A

fixed and definite ratio

51
Q

what happens to the properties of constituent elements in a compound

A

constituent elements lose their properties

and the compound’s properties are different from its constituent elements

52
Q

properties of hydrogen and oxygen different from its compound ( H2O)

A

hydrogen is combustible and burns with a pop sound
oxygen is a supporter of combustion
but water is neither of those and it is rather used as a fire extinguisher
- H2 & O2 are gases whereas H2O is a liquid

53
Q

how can elements in a compound be separated

A

chemical methods or by electrolysis (passing of electricity)

54
Q

what is iron pyrite

A

iron disulphide (FeS2)

55
Q

alcohol and water is a homo or hetero mixtrure

A

homogenous mixture

56
Q

what are physical properties?

A

those properties which can be observed and measured without changing the identity or the composition of the substance

57
Q

what are chemical properties?

A

those that can be measured only by a chemical reaction and cannot be determined by touching or viewing the substance

58
Q

what does chemical properties show?

examples ?

A

the kind of reaction in which a substance can take place

acidity or basicity, combustibility, reactivity etc

59
Q

what is physical quantity?

A

a property of a material or system that can be quantified by measurement

60
Q

physical quantity is measured in 2 parts

A

a numerical coefficient and a unit

61
Q

what is a unit?

A

a standard of reference chosen to measure or express any physical quantity

62
Q

what is SI ?

A

International system of units

63
Q

what does SI have?

A

has seven base units pertaining to seven fundamental scientific quantities

64
Q

what are derived units

A

physical quantities derived using SI base units in combinations

Chemistry Aakash (1 decks)

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