Chemistry Matter, its Properties, their Measurement and Uncertainty in Measurement

Topics covered :

This lecture covers the following topics :

`●` Introduction
`●` Nature of Matter
`●` Classification of Matter
`●` Properties of Matter and their Measurement
`●` System of Measurement
`●` The International System of Units (SI)
`●` Quantities used Frequently in Chemistry

Chemistry :

Science can be viewed as a continuing human effort to systematize knowledge for describing and understanding nature.

`=>` Science is sub-divided into various disciplines like chemistry, physics, biology, geology etc. for the sake of convenience.

Definition of Chemistry : It is the branch of science that studies the composition, properties and interaction of matter. The aspects of matter can be best described and understood in terms of basic constituents of matter i.e. atoms and molecules.

`text(Note)` : (i) Cis-platin and taxol are effective in cancer therapy.
(ii) AZT (Azidothymidine) used for helping AIDS victims.


`=>` Dry ice along with ether is used as refrigerant. Drugs given to make a patient unconscious before operation are called anesthetics, and drugs used as pain killers are called sedatives.

`=>` Anaemic patients are deficient in iron.

`=>` Fertilisers contain `N`, `P` with `H` as essential constituent. Thus, chlorine is not generally present in fertilizers.

`=>` Bones are considered as reservoir of `Ca`, `Mg` and `PO_4^(3-)` ions. Thus, the main constituent of bones is calcium phosphate.

`=>` The substance present in abundant amounts in sea-water is common salt (`NaCl`) with significant amount of `Mg^(2+)` ions also.

`=>` Many life saving drugs have been isolated from plant and animal sources or prepared by synthetic methods.

`=>` Production of superconducting ceramics, conducting polymers, optical fibres and large scale miniaturization of solid state devices is possible. With a better understanding of chemical principle it has now become possible to design and synthesize new materials having specific magnetic, electric and optical properties.

`=>` CFCs (chlorofluorocarbons) is the environmentally hazardous refrigerants which is responsible for ozone depletion in the stratosphere.

`=>` A gas that cannot be collected over water is `SO_2`.

`=>` The purity of gold is generally expressed as carats. The pure gold is known as 24 carats.

`=>` Vitamin `B_(12)` cyanocobalamine contains cobalt.

`=>` Phenolpthalein gives colour when the solution is alkaline.

`=>` `Ca^(2+)`, `Mg^(2+)` sets of ions associated with hard water.

`=>` Carbogen is a mixture `O_2` and `CO_2`.

`=>` Rubber is made hard and strong by adding sulphur.

`=>` The major constituent of the atmosphere is nitrogen. Our atmosphere contains about `79%` nitrogen.

`=>` Iodine is most soluble in `KI`(aq). `KI +I_2 → KI_3`. In fact `KI` is one of those important compounds which can absorb as well as gives off `I_2` on heating.

`=>` Sodium thiosulphate is used in photography because of its complex forming behaviour. It is used for the removal of undecomposed silver bromide from the film. A complex is formed in this process `[Ag (S_2O_3)_2]^(3-)`.

`=>` Gases exert pressure due to collision of their molecules with the wall of container. The dimensions of pressure are same as that of energy per unit volume.

Nature of Matter :

Matter : Anything which has mass and occupies space is called matter.

e.g. Book, pen, water, air, etc.

Physical States of Matter : (i) Solid State
(ii) Liquid State
(iii) Gaseous State

Different States differ in freedom of movement and closeness of particles
Properties of Solids : (i) The particles are held very close to each other in an orderly fashion.
(ii) Freedom of movement is very low.
(iii) They have definite volume and definite shape.

Properties of Liquids : (i) The particles are close to each other.
(ii) They have more freedom of movement as compared to solids.
(iii) They have definite volume but not the definite shape.

Properties of Gases : (i) The particles are very far apart from one another.
(ii) They have very high speed of movement.
(iii) These have neither definite volume nor definite shape.

`text(Solid) undersettext(cool) oversettext(heat) ⇌ text(Liquid) undersettext(cool) oversettext(heat)⇌ text(Gas)`

Classification of Matter :

This classification of matter is based on the whether the ratio of substances is fixed or not.



See Fig

Mixture :

Mixture : A mixture is a substance which has two or more substances mixed in any ratio.


Types of Mixture : There are two types of mixture. classified on the basis whether the composition is uniform or not.

(a) Homogeneous Mixture : In this, all the components mix completely with each other and its composition is uniform throughout. e.g. sugar solution, air etc.

(b) Heterogeneous Mixture : Its composition is not uniform throughout. Sometimes different components of mixture can be seen. e.g. mixture of salt and sugar, mixture of grains and pulse.


`text(Note)` : Both types of mixture can be separated into their components by mechanical and physical methods.

Pure Substances :

They have fixed composition. e.g. Glucose contains `C`, `H` and `O` in a fixed ratio and gold, silver etc.

`text(Note)` : Constituents of pure substances can't be separated by simple physical methods.

Classification of pure substance :

This classification is based on whether substance consists of only one type of particles or more than one type of particles.

(a) Elements : It consists of only one type of particles. i.e. one type of atoms or molecules. e.g. `Na`, `Cu`, `Ag`, `H`, `O` etc.

`text(Note)` : (i) Elements contain only one type of atom held together as their constituent particles. e.g. `Na` etc.

(ii) In some elements two or more atoms combine to give molecules of the element. e.g. `H_2`, `O_2` etc.

See Fig.1.3.

(b) Compounds : These are obtained by combining two or more atoms of different elements. e.g. water (`H_2O`) ammonia (`NH_3`) etc. See Fig.1.4.

`text(Note)` : (i) In a compound different elements are present in a fixed ratio.

(ii) Properties of compounds are different from its constituent elements.

e.g. Preparations of water from hydrogen and oxygen.

(iii) The constituents of a compound can not be separated into simple substances by physical methods. But can be separated by chemical methods.
Q 2614867750

Observe the pictures carefully and label A, B and C appropriately

(A)

A → molecule, B → atom, C → compound

(B)

A→ compound, B → molecule, C → atom

(C)

A → atom, B → compound, C → molecule

(D)

A → compound , B → atom, C → molecule

Solution:

Picture A is of oxygen molecule B is of sodium atom. It can also be considered as mono atomic molecule. C is of water compound.

Some elements such as sodium or copper contain single atoms held together as their constiuent particles whereas in some others two or more atoms combine to give molecules of the element . Thus hydrogen nitrogen atoms combine to give their respective molecules. When two or more atoms of different element combine, the molecule of a compound is obtained. The examples of some compounds are water, ammonia, carbon dioxide and sugar etc.
Correct Answer is `=>` (D) A → compound , B → atom, C → molecule

Properties of Matter and their Measurement :

Every substance has unique properties. Each substance has two types of properties :

(a) Physical Properties

(b) Chemical properties



Physical Properties :

These are the properties in which identity or composition of the substance remain same. e.g. colour, odour, melting point, boiling point, density etc.

Chemical Properties :

These are the properties in which there is a change in identity or composition of the substance. e.g. acidity or basicity, combustibility etc.

Measurement of Properties :

Many properties of matter are quantitative in nature. e.g. length, area, volume etc.

Representation of Quantitative Measurement : It is represented by a number followed by units in which it is measured.

e.g. If length of a room = `6` `m`

Here `6` = number and `m` = unit in which length is measured.

6 is meaningless unless its unit is given.

System of Measurement :

(i) English System

(ii) Metric System


`text(Note)` : (a) Metric system was originated in France.

(b) Metric system is more convenient because it is based on decimal system.

Since both the systems are based on different concepts, therefore need of a common standard system was felt. So, a system was established (1960) known as the international system of units (SI).

(c) Kilogram is defined as mass of platinum-iridium (Pt-Ir) cylinder that is stored in an airtight jar at International Bureau of Weights and Measures in Sevres, France. Pt- Ir was chosen as a reference standard because it is highly resistant to chemical attack and its mass will not change for an extremely long time.

(d) The metre was redefined in 1983 by CGPM as the length of path travelled by light in vacuum during a time interval of 1/299792458 of a second.
Q 2674167956

What is the expansion of CGPM ?

(A)

Conference Generale des Poids et Measmes

(B)

Conference Generale des Po ids et Measurement

(C)

Community Generale des Poids et Measures

(D)

Convention General des Poids et Measurement

Solution:

CGPM-Conference Generale des Poids et Measures
Correct Answer is `=>` (A) Conference Generale des Poids et Measmes
Q 2624178051

Observe the relationship on LHS and RHS of : : carefully : NMI : National Metrology Institute : : NPL : ? ? refers to

(A)

National Picture Lamination

(B)

National Physical Laboratory

(C)

Number pictogram label

(D)

Numerological picture of Laboratory

Solution:

NPL→ National Physical Laboratory.
Correct Answer is `=>` (B) National Physical Laboratory

The International System of Units (SI) :

(i) It was established by the `11^(th)` general conference on weights and measures.

(ii) The SI system has seven base units. See Table 1.1.

These units pertain to the seven fundamental scientific quantities. Other physical quantities can be derived from these quantities.

Definitions of SI base units are given in Table 1.2.

The SI system also allows use of prefixes. Prefixes are used to indicate the multiples or sub multiples of a unit. See Table 1.3.

Q 1983678547

What is the SI unit of mass? How is it defined?
Class 11 Exercise 1 Q.No. 14
Solution:

S.I. unit of mass is kilogram (kg). It is equal to the
mass of the international prototype of the
kilogram. It is defined as the mass of platinumiridium
cylinder that is stored in air-tightjar at
International Bureau of Weights and Measures
in France

Quantities used frequently in Chemistry :

(i) Mass and Weight : Mass is the amount of matter present in the substance.

Weight is the force exerted by gravity on an object.

`text(Note)` : (a) the mass of a substance is constant.

(b) The weight of a substance change on going from one place to other due to gravity.

The mass of substance is determined using a Analytical balance. See Fig 1.5.

(ii) Volume : It has units of (`text(length)^3`) i.e. `m^3`.

A common unit litre (L) is used for measuring volume of liquid. It is not a SI unit.

`1L = 1000 mL = 1000 cm^3 = 1 d m^3`

See Fig.1.6 to visualise the interconversion of units.

In Laboratory, volume of liquids or solutions is measured by graduated cylinder, burette, pipette etc.

For preparing a known volume of a solution, volumetric flask is used. See Fig 1.7.

(iii) Density : It is defined as the mass of a substance per unit volume.

`d = m/V`

Where `d =` density

`m =` mass

`V =` volume

Its unit is `Kgm^(-3)`

(iv) Temperature : Temperature is measured using there common scales which are as follow :

(a) Degree Celsius (`text()^oC`)

(b) Degree Fahrenheit (`text()^oF`)

(c) Kelvin (`K`)

`text(Note)` : Kelvin (`K`) is the SI unit.

The celcius scale is calibrated from `0^o` to `100^o` and the Fehrenheit scale is represented between `32^o` to `212^o`.

Relation between `text()^oF` and `text()^oC` scale

`text()^oF = 9/5 (text()^oC) + 32`

Relation between `text()^oC` and `K` scale.

`text(Note)` : The negative value of temperature is possible in celsius scale but not in Kelvin scale.
Q 2614478350

What should be the volume of the milk (in `m^3`) which measures `5 L?`

(A)

`5xx10^(-3) m^3`

(B)

`5xx10^3 m^3`

(C)

`5xx10000 m^3`

(D)

`5xx10^6 m^3`

Solution:

Since, `1L = 10^(-3) m^3`

So, `5 L = 5xx10^(-3) m^3`
Correct Answer is `=>` (A) `5xx10^(-3) m^3`
Q 2664478355

The greatest length of the following values given is

(A)

`4.0 m`

(B)

`140` in

(C)

`12 ft`

(D)

`0.001 km`

Solution:

• `1` in `=2.54cm`
`therefore 140` in ` = 2.54xx140 = 355.6 cm`

or `140` in ` = 3.556 m` `( because 1 m = 100 cm)`

• `1 ft = 30.48cm.`

`therefore 12ft = 12 xx 30.48 = 365.76cm = 3.65m`

• `1 km = 1000 m`

`therefore 0.001 km = 1000 xx 0.001 =1m`

On comparing all the given values of lengths, `4m` is greatest
length.
Correct Answer is `=>` (A) `4.0 m`
Q 2614578459

Which of the following has the largest volume?

(A)

445 g of water at 4°C (density = 1 g / `cm^3` )

(B)

600 g of chloroform at 20°C ( density = 1.5 g / `cm^3` )

(C)

`155 cm^3` of steel

(D)

`0.50 L` milk

Solution:

The largest volume of the following group is `0.50 L` milk
• `445 g` of water at `4^0C = 445cm^3` of water at `4^0C`
• `600 g` of chloroform at `20^0C` (density `= 1.5 g//cm^3 `)

`because 1.5 g = 1 cm^3`

`600 g = 1/(1.5) xx 600 = 400 cm^3` of chloroform at `20^0 C`

• `155 cm^3` of steel

• `0.50 L` of milk `= 0.50 xx 10^6 cm^3 = 500000 cm^3`
Correct Answer is `=>` (D) `0.50 L` milk
Q 2634578452

The highest temperature of the following values given is

(A)

`217 K`

(B)

`273 K`

(C)

`217^0 F`

(D)

`105^0 C`

Solution:

The highest temperature is `105^0C`. Convert `217 K` into `text()^0C`

(i) `217 K = text()^0C + 273.15`

`text()^0C =217 K -273.15K = -56.15K`

Convert `273 K` into `text()^0C`

(ii) `273 K = text()^0C + 273.15`

`273K -273.15K = text()^0C => text()^0C =- 0.15K`

Convert `217^0F` into `text()^0C`.

(iii) `217^0 F = 9/5 text()^0C+32`

`(217-32) = 9/5 text()^0C`

`(185xx5)/9`

`1^0C = 102.7^0F`
Correct Answer is `=>` (D) `105^0 C`
Q 2664678555

Of the following substances, the greatest density is of

(A)

`1000g` of water at `4^0 C`

(B)

`100.0 cm^3` of chloroform weighing `198.9 g`

(C)

a `10.0 cm^3` piece of wood weighing `7.72 g`

(D)

an ethly alchohol - water mixture of density `0.83 g//cm^3`

Solution:

(i) `1000 g` of water at `4^0 C` (density/`g//cm^3`)

`(1000 g)/(1000 cm^3) = 1 g// cm^3`


(ii) `100.0 cm^3` of chloroform weighing `198.9g`

` = 1.989 g//cm^3`

(iii) a `10.0 cm^3` piece of wood weighing `7. 72 g`

` = 0.772 g// cm^3`

(iv) an ethyl alcohol-water mixture of density `0.83 g//cm^3`.

The greatest density is of `100.0 cm^3` of chloroform weighing `198.9 g.`
Correct Answer is `=>` (B) `100.0 cm^3` of chloroform weighing `198.9 g`
Q 2654778654

Which of the following represents the largest unit?

(A)

Decilitre

(B)

Crecalitre

(C)

Kilolitre

(D)

Megalitre

Solution:

The largest unit is megalitre.
Correct Answer is `=>` (D) Megalitre
Q 2614878750

Which measurement represents the largest quantity?

(A)

`47.3 mg`

(B)

`4730 ng`

(C)

`4.73xx10^(-4) g`

(D)

`4.73 xx 10^3 mug`

Solution:

`47.3` mg represents the largest quantity

(i) `47.3 mg = 47.3 xx10^(-3) g`

(ii) `4320ng = 4730xx10^(-9) g`

(iii) `4.73xx10^(-4)` g

(iv) `4.73xx10^3 mu g = 4.73xx10^3xx10^(-6)`

` = 4.73xx10^(-3) g`

Here, n stands for nano
Correct Answer is `=>` (A) `47.3 mg`
Q 2644878753

Which measurement represents the smallest quantity?

(A)

`2950 ng`

(B)

`2.95xx10^(-4) g`

(C)

`2.95xx10^3 kg`

(D)

`2.95xx10^(-6) kg`

Solution:

`2950 ng` represents tile smallest quantity.

` = 2950xx10^(-9) g`

` = 2.950xx10^(-6) kg`
Correct Answer is `=>` (A) `2950 ng`
Q 2604878758

What is the value of temperature `75^0F` on the Kelvin scale?

(A)

`24 K`

(B)

`318K`

(C)

`297K`

(D)

`215K`

Solution:

`75 = 9/5 text()^0C+32 = (43xx5)/9 text()^0 C = 23.9^0 C`


`K = 23.9+273`

`K = 296.9 approx 297K`
Correct Answer is `=>` (C) `297K`
Q 2634078852

How many seconds are there in 3 days?

(A)

`259200 s`

(B)

`172800 s`

(C)

`24800 s`

(D)

`72000 s`

Solution:

Seconds in 3 days can be calculated as

`3 text(days) xx24h xx 60 text(min) xx 60 sec = 3 xx24 xx 60 xx 60`


` = 259200 sec`
Correct Answer is `=>` (A) `259200 s`
Q 1973878746

Match the following prefixes with their
multiples:








Column IColumn II
Prefixes Multiples
(i) micro `10^6`
(ii) deca `10^9`
(iii) mega `10^(-6)`
(iv) giga `10^(-15)`
(v) femto `10`

Class 11 Exercise 1 Q.No. 15
Solution:

micro `= 10^(-6)`, deca `= 1 0`, mega `= 10^6`, giga `= 10^9`,
femto `= 10^(-15)`

 
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