Class 7 Chemistry CBSE

Chemistry Concept Maps Class VII • General Chemistry • Sorting Materials In Groups • Physical and Chemical Change • Acids, Bases and Salts • Fibre To Fabric • Air • Separation of Substancs • Water A Precious Resources • Waste Water Story

Magnetic recording tapes , video cassettes curtains

1. Absorbs less water 2. Strong , light,elastic and resists wrinkles

Uses

Light, elastic and high tensile strength

Properties

Properties

Cotswool, polycot, terrywool

Blended

Umbrellas, parachutes, socks Uses

Polyester (terylene or mylar or dacron) Nylon

Wool

FIBRES

Natural

Acrylic (Orlon or Acrilan)

Synthetic

A thread or filament from which a cloth is made

Silk

Uses

Cotton

Semi synthetic Properties

Formation

Air and water proof

Rayon (Artificial silk) Shirt, ties, lining etc.

Uses

Properties 1. Absorbs moisture 2. Lustrous and resembles silk

Uses

Warm, soft and light

Sweaters, socks

Spandex (Lycra)

Koroseal

Viscose process

Properties

Uses Rain coat, bathroom curtains

Properties High elasticity and stretchable

Swimming costumes caps, T-Shirts

Liquid N2 boils off followed by liquid O2

Fractional distillation

Heavy impurities settle down

Sedimentation Filtration

SEPARATION OF GASES FROM AIR

CITY WATER SUPPLY

Suspended impurities separates

Chemical change

CHANGES

Example

Definition

Purification

Liquefaction

Physical change

Sterilization

Example

Definition Characteristics Removal of dust, gases & water vapour

Removal of harmful micro organism

Characteristics

Water

Alcohol

Solvent MgO

Al2O3

Adsorbent medium

Principle (Ability to sublime) Example (Sand/I2)

Method

Principle (Density)

Filter paper

Principle (Relative solubility & affinity of constituents)

Principle (Solubility)

Sublimation

Example (separation of cream from milk)

Centrifugation

Chromatography

Principle (Density)

Example (Ink/water)

Separating funnel

SEPARATION TECHNIQUES

Using Suitable Solvent Example (Sugar/Sand)

Example (Oil/Water)

Fractional distillation

Evaporation Distillation Principle (Boiling point)

Example (NaCl/Water)

Principle (Boiling point)

Principle (Boiling point)

Example (Alcohol/water)

NaCl + H2O + Heat

acid > H2O H2O

> acid

Dilute acid

Compounds which when dissolve in water gives H+/H3O+ ions e.g. HCl, H2SO4

Mineral acids

On the basis of Source

Definition

Acids

Solution conduct electricity

On the basis of strength Strong acids

Weak acids

Almost completely ionise (H2SO4 , HCl)

Partially ionise

HCOOH a

c

Olfactory Substances whose odour changes in acidic or basic solutions

Concentrated base

On the basis of concentration

Definition

+

Bases

Acids sour in taste bases bitter in taste

Classification

Soluble in water

Properties

Acids turns blue litmus to red base turns red litmus to blue

On the basis of strength

Strong base

Almost completely ionise (NaOH, KOH) Which indicates the nature of particular solution

i d

Indicator

base > H2O

> base

Dilute base

Classification

Organic acids (e.g. HCOOH, CH3COOH)

Neutralization

Concentrated acid

On the basis of concentration

e.g. (H2SO4, HCl)

HCl + NaOH

Compounds which when dissolve in water gives OH– ions e.g. NaOH, NH4OH H2O

Weak base Methyl orange

Partially ionise NH4OH, Ca(OH)2

Artificial

Phenolphthalein

Natural

• Shearing : The fleece of the sheep along with a thin layer of skin is removed from its body.

(saris, jeckets , gloves, carpets) Uses

Scouring :The sheared skin with hair is thoroughly washed

in tanks to remove grease, dust and dirt Sorting : Separation of hair of different textures is called sorting

(Shiny) Properties

Silk

Wool Plant and animal fibres

Cotton

Jute

FIBRE TO FABRIC

Synthetic or man made

A thread like part in animal and vegetable tissues

Modified natural fibres

Nylon

Semi Synthetic

Rayon (Artificial silk)

1. Absorbs moisture 2. Lustrous and resembles silk

Septic tanks, chemical toilets, combusting pits The excessive growth of algae and aquatic plants due to added nutrients

Sewage disposal

Eutrophication

Humans excreta is treated by earthworms

Vermi-processing toilet

Chemical Oxygen demand (COD)

Sanitation & disease

Poor sanitation and contaminated drinking water is the cause of a large number of dieseases

Index of the waste of water which can be oxidised by strong oxidising agents

WASTE WATER STORY e.g. • Pathogens such as bacteria virus, parastic worms • Soluble organic material such as urea, proteins • Gases such as H2S, CO2, CH4

Consitutent Cleaning of waste water

Biological Oxygen demand (BOD)

Major of the oxygen utilised by microorganisms during oxidation of organic materials

Waster water treatment plant WWTP Treatment of waste water using physical, chemicaland biological process

Solid e.g. ice Liquid e.g. H2O(l)

Gaseous e.g. water vapours

Forms of water Water management proper use of water

e.g. Oceans, rivers, lakes, ice caps

Availability of water

Increasing population

Element hydrogen & oxygen

Water a precious resources

Depletion water table

Composition of water Mass ratio hydrogen : oxygen 1 : 8

Increasing industries

Water cycle Chemical properties Action with litmus Inert

Physical properties

Density 1 gm/cc Action with metals 2K + 2H2O(l)

2KOH(aq) + H2O(g)

Melting point 0ºC

Boiling point 100ºC

Moving air

Sailing yachts

Wind mill Exosphere

Dispersal of seeds

Thermosphere

Birds , bats can fly

Uses

Mesosphere Other gases, carbon dioxide (0.03%) and water vapour

Argon (0.934%)

AIR

Stratosphere

Oxygen (20.946%)

Composition

Atmosphere Troposphere

The transparent, thick and invisible envelope of air surrounding us

Nitrogen (78.084%)

He, Ne, Ar, Kr, Xe

Inert gases

Dust

Components CO2

Water vapour Oxygen

Nitrogen

Change that alters the physical properties of matter without changing the chemical composition Copper sulphate solution Sand Sand bath Wire gauze

Iron vessel

Action of heat on iodine

Switching on an electric bulb

Defintion No new product is formed

Burner

No net gain or loss of energy

Tripod stand

(Pure soluble substance seprates out in the form of crystals)

Crystallisation

Example

Physical changes

Characterstics

Change is temporary and reversible

Dissolving of NaCl in water

No change in the weight of substance

CHANGES IN MATTER

Change in the weight of new substance Change is permanent and irreversible

Defintion

Characterstics New product is formed Net gain or loss of energy

Chemical changes

Change that alters the chemical properties of matter with changing the chemical composition

Air

Burning of Mg in air

Example

Corrosion

Air

Layer of oil

1. Presence of air Rusted nails 2. Presence of water

Dry Air

Non-rusted nails

Non-rusted nails

Anhydrous CaCl2

Conditions (A) (Air and Water)

Burning of LPG

Rusting Preventation

Defination (Iron surface gets covered with a brown flaky substance)

(B) (Boiled distilled water)

Equation 4Fe + xH2O + 3O2

2Fe2O3.xH2O

1. Iron surface coating with thin layer of paint, varnish 2. Iron surface coating with zinc (galvanization) 3. By alloying (Fe, Cr, Ni)

(C) (Only dry air)