All matter has physical and chemical properties. Extensive properties are those properties of a substance which depend on the amount of substance. They vary with the amount of the substance. Examples: Mass, weight, and volume. Intensive properties are those properties of a substance which do not depend on the amount of substance. Examples: colour, melting point, boiling point, electrical conductivity, and physical state at a given temperature.

Physical Properties of Substance:

Physical properties are characteristics that can be measured or observed without changing the composition of the substance under study. All samples of a pure substance have the same chemical and physical properties. Physical properties can be extensive or intensive. 

Mass

A mass is the amount of matter that is found in a substance. Mass is expressed in terms of kilograms (kg).

Density

Density is the measurement of mass with respect to and in a relationship with volume. The mass of a substance per its unit volume is called density. Density is expressed in kilograms per cubic metre (kg/m³). Mathematically

Density = Mass / Volume

The density depends on the temperature and pressure of the substance. The effect is prominent in cases of gases. The application of increasing temperature decreases its density because its volume increases with increasing temperatures, and the application of increasing pressure increases density because the volume decreases with increasing pressure.

Volume

Volume is the measurement of the quantity or amount of matter in a three dimensional space. It is the space occupied by the substance. Volume is expressed in cubic metres (m³).

Boiling Point:

The temperature at which a liquid changes its state to a gas at atmospheric pressure is called the boiling point of that liquid.  It is defined as the temperature at which the vapour pressure of the liquid becomes equal to the atmospheric pressure. This is the point at which both liquid and gaseous phase exists at equilibrium. The boiling point of the substance also varies with pressure and is specified at standard pressure.

The boiling point of a liquid is a characteristic property and can be treated as a criterion for the purity of liquid.  It increases with the increase in external pressure. Liquids having greater intermolecular forces have high boiling points.

Melting Point:

The temperature at which a solid changes its state to a liquid at atmospheric pressure is called the melting point of that solid. This is the point at which both liquid and solid phase exists at equilibrium. The melting point of the substance also varies with pressure and is specified at standard pressure.

The melting point of a liquid is a characteristic property and can be treated as a criterion for the purity of a solid.  It increases with the increase in external pressure. Solids having greater intermolecular forces have high melting points.

Conductivity

Conductivity is the measure of a substance’s ability, or lack of ability, to conduct electricity or heat. Some matter has a high level of conductivity and other matter has a high level of resistance to the conduction of electricity.

Heat Capacity

Simply stated, heat capacity is the amount of heat that must be added or taken away from a substance to achieve a certain temperature. Heat capacity is also referred to as thermal capacity and the amount of heat that is added or taken away is measured in terms of joules per kelvin.

Deliquescence:

Deliquescence refers to the property of a substance to absorb water from the air to dissolve itself and form an aqueous solution. Materials showing deliquescence are termed deliquescent. In order to be deliquescent, a substance must both absorb a large amount of water and be sufficiently soluble to dissolve in it. Examples: Sodium hydroxide, potassium hydroxide, anhydrous potassium chloride, anhydrous magnesium chloride, anhydrous ferric chloride show deliquescence.

Hygroscopicity:

Hygroscopicity is the tendency of a solid substance to absorb moisture from the surrounding atmosphere and are converted into hydroxides or hydrates. Anhydrous copper sulphate, quick lime (CaO), anhydrous sodium carbonate, etc. are hygroscopic in nature.

Efflorescence:

Efflorescence is a spontaneous loss of water by a hydrated salt, which occurs when the aqueous vapor pressure of the hydrate is greater than the partial pressure of the water vapour in the air. Washing soda (Na₂CO₃·10H₂O), Glauber’s salt or sodium sulphate (Na₂SO₄·10H₂O), Ferrous sulphate (FeSO₄·7H₂O), potash alum (K₂SO₄· Al₂(SO₄)₃.24H₂O) show efflorescence.

Mechanical Properties of Substance:

Strength:

It is the property of a material which opposes the deformation or breakdown of material in presence of external forces or load. Engineering materials must have the suitable mechanical strength to be capable to work under different mechanical forces or loads. It is shown by solids.

Toughness:

Toughness is the ability of a material to absorb energy and gets plastically deformed without fracturing. For good toughness, materials should have good strength as well as ductility. To be tough, the material should be capable to withstand both high stress and strain. It is shown by solids.

Elasticity:

Within elastic limit, the solid completely regains its original shape, size or volume after removal of deforming force, then the property is called elasticity. Steel, copper, aluminium show elastic behaviour.

Plasticity:

If a body is stressed beyond elastic limit, and it does not regain original shape, size, and volume after removal of deforming force, then the property is called plasticity. These substances can be given required shape very easily. Example: Plaster of paris

Hardness:

It is the ability of a material to resist permanent shape change due to external stress. There are various measures of hardness – Scratch Hardness, Indentation Hardness, and Rebound Hardness. Scratch Hardness is the ability of materials to oppose the scratches to the outer surface layer due to external force. It is shown by solids.

It is measured on Mohs’ scale. The Mohs’ scale of mineral hardness is a qualitative ordinal scale that characterizes the scratch resistance of different minerals through the ability of a harder material to scratch a softer material. It was created by the German geologist and mineralogist Friedrich Mohs in 1812.

On Moh’s scale hardness of a diamond is maximum (10) and that of talk is minimum (1). If a material can scratch topaz but can’t scratch corundum, then it possesses hardness equal to 8.

Brittleness:

The brittleness of a material indicates that how easily it gets fractured when it is subjected to a force or load. The solids of non-metal are generally brittle in nature. The brittleness of the material is temperature-dependent. Some metals which are ductile at normal temperature become brittle at low temperature. Hardness and brittleness are inverse properties. The harder the substance, the more brittle it is. It is shown by solids.

Malleability:

Malleability is a property of solid materials which indicates that how easily a material gets deformed under compressive stress. Malleability is often categorized by the ability of the material to be formed in the form of a thin sheet by hammering or rolling. This mechanical property is an aspect of the plasticity of the material. The malleability of material is temperature-dependent. With the rise in temperature, the malleability of material increases. This is the characteristic property of metals. Copper, aluminium, gold, silver show malleability. Gold is the most malleable metal.

Ductility:

Ductility is a property of a solid material indicates that how easily a material gets deformed under tensile stress. Ductility is often categorized by the ability of a material to get stretched into a wire by pulling or drawing. This mechanical property is also an aspect of the plasticity of material and is temperature-dependent. With the rise in temperature, the ductility of material increases. This is a characteristic property of metals. Copper, aluminium, gold, silver show ductility. Platinum is the most ductile metal.

Creep:

Creep is the property of a material that indicates the tendency of a material to move slowly and deform permanently under the influence of external mechanical stress. It results due to long time exposure to large external mechanical stress within the limit of yielding. Creep is more severe in materials that are subjected to heat for a long time.

Resilience:

Resilience is the ability of material to absorb the energy when it is deformed elastically by applying stress and release the energy when stress is removed. Proof resilience is defined as the maximum energy that can be absorbed without permanent deformation. The modulus of resilience is defined as the maximum energy that can be absorbed per unit volume without permanent deformation.

Fatigue:

Fatigue is the weakening of a material caused by the repeated loading of the material. When a material is subjected to cyclic loading, and loading greater than a certain threshold value but much below the strength of the material (ultimate tensile strength limit or yield stress limit), microscopic cracks begin to form at grain boundaries and interfaces. Eventually, the crack reaches a critical size. This crack propagates suddenly and the structure gets fractured.

Chemical Properties of Substance:

Chemical properties are characteristics that can only be measured or observed as matter transforms into a particular type of matter. The tendency of matter to react chemically with other substances is known as reactivity.

Reactivity:

The tendency of matter to combine chemically with other substances is known as reactivity. Certain materials like chlorine, potassium, sodium, etc. are highly reactive, whereas others like gold, platinum, etc. are extremely inactive.

Flammability:

The tendency of matter to burn is referred to as flammability. As matter burns, it reacts with oxygen and transforms into various substances. Example: wood, paper, etc. are flammable. Petrol, ethyl alcohol are highly flammable.

Toxicity:

Toxicity refers to the extent to which a chemical element or a combination of chemicals may harm an organism. Methyl alcohol, methyl isocyanate are highly toxic.

Reactivity with Acids and Bases:

A substance’s ability to react with an acid or a base is a chemical property.

Science > Chemistry > Introduction to Chemistry > Properties of Substance

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In previous articles, we have studied measurements of length, area, and volume by different methods. In this article, we shall study the measurement of mass and weight of a body.

Measurement of Mass of a Body:

Mass is a measure of matter contained in a body. More the substance more the mass. Mass is a measure of the inertia of the body. Thus more mass the body has, the more it resists any effort to move it. S.I. unit of mass is the kilogram (kg). Its c.g.s. unit is gram (g). Mass is a scalar quantity.

one kilogram is a mass of a cylindrical piece made up of platinum-iridium alloy kept in the International Bureau of Weights and Measures at Sevres near Paris in France.

Common balance or physical balance are mostly used devices for the measurement of mass. Spring balance, table balance, platform balance, roman steelyard, triple beam steelyard are a few of the other types of balance.

Measurement of Mass by Use of Beam Balance:

Working Principle:

A beam balance works on the principle of moments. According to the principle of moments at equilibrium, the anti-clockwise moment due to the weight of an object on the left pan of the beam is equal to the clockwise moment due to the standard weights on the right pan of the beam.

Construction:

The physical balance consists of a light and rigid beam of brass, a metallic pillar, a wooden base, two pans, a metallic pointer, and an ivory scale. The plumb-line indicates whether the balance is horizontal. In an ideal condition, the plumb-line is aligned with the end of the knob fixed to the pillar. When the beam is horizontal the pointer remains on zero mark on the ivory scale. The device is enclosed in a glass box to avoid the effect of wind. The whole box has leveling screws at the bottom to set it horizontal. A lever arrangement is provided at the baseboard for raising or lowering the beam by raising and lowering of the platform. A weight box containing standard weights comes with the balance.

Use of Beam Balance:

Common balance is used to find unknown mass by using known standard masses.

• By adjusting levelling screw the plumb line is brought just above the pointed projection on the balance.
• The beam is raised using the lever and checked that the pointer swings equally on either side of the zero mark.
• Now, beam is lowered and an unknown mass is kept in one pan of the common balance.
• Next known masses are put in the second pan such that the pointer lies at the centre (zero mark) or the scale swings equally on both sides of the zero mark.
• The total known mass in the other pan is calculated, which gives the mass of the object.

Measurement of Mass of a Liquid or a Gas:

• Use the beam balance to find the mass of empty beaker or closed container. Note the Mass M₁ kg.
• Fill the beaker with the liquid or the closed container with gas.
• Find the mass of the beaker with the liquid or the closed container with gas, Note this mass M₂ kg
• Then M₂ – M₁ gives the mass of the liquid or the gas.

Requisite of Good Balance:

• A balance is considered to be true if its beam remains horizontal when equal weights or no weights are placed on the two pans. It is possible when the arms of the two balances are of equal length, the weights of two pans should be equal. The centre of gravity of the pan beam should pass through the fulcrum when the beam is horizontal.
• The balance should be sensitive. It should show a large deflection for a small difference in weights present in the two pans. It can be achieved by increasing the length of the arms of the beam.
• A beam balance should be stable. It should return to equilibrium conditions after being disturbed. It can be achieved by making the beam heavy.
• The beam of the balance must be made up of metal which is rigid so that there is no deformation in it.
• It is to be noted that a balance cannot be sensitive and stable at the same time as the condition required for sensitivity is that the centre of gravity of the beam along with the pans etc. must be near to the fulcrum, while the condition for stability is that the centre of gravity of the beam along with pan should be below fulcrum and at large distance from it. These two conditions are opposite to each other hence compromise between the sensitivity and stability is made.

Precautions in Using a Beam Balance:

• The weights should be carried with forceps. They should not be carried with bare fingers to avoid the change in its weight due to the presence of moisture and dust particles.
• The weights and the body whose mass is to be measured should be dry.
• When the pointer is near zero mark, the weights should be tried in the descending order.
• The beam should be lowered each time before adding or removing weights from the pan.
• The weight should be kept back into the weight box after using it.
• The lever should be turned gently, in order to prevent the knife edges from breaking.

Weight of a body:

The gravitational force of attraction (pull) exerted by the Earth on a body is called the weight of the body. It is a vector quantity. S.I. unit of weight is newton (N). It is measured using a spring balance.

The weight of a body is given by

W = mg

Where, m = mass of a body g = acceleration due to gravity

As the acceleration due to gravity ‘g’ changes from place to place and from planet to planet, the weight of the body is not constant. On the Earth, the value of acceleration due to gravity ‘g’ is the least on the equator and the highest on the poles. Hence the weight of the body on the equator is a least while the weight of the same body on the poles is the highest. In our planet system, the acceleration due to gravity on Jupiter is the highest. Hence the weight of a body on Jupiter is the highest.

Measurement of Weight of a Body:

Weight of a body is measured using a spring balance. A spring balance has a spring inside. A hook is attached to this spring which hangs down the body of the spring balance. The object to be weighed is suspended from the hook and weight is indicated on the graduated scale.

The spring balance works on the principle which states that the weight of the body attached to the hook of the spring balance is directly proportional to the extension of the spring. Thus more the weight more the extension and less the weight, less is the extension. Due to this relation, the graduated scale of the spring balance is linear.

Note: When we use beam balance we compare the weight of the body with standard weights. In this case, actual measurement of weight is not done.

Check the Validity of Following Statements.

“An astronaut whose mass is 84 kg on the earth will have an approximate mass of 14 kg on the moon”

This statement is not correct because mass remains constant. It does not change with a place.

“An astronaut whose weight is 840 N on the earth will have an approximate weight of 140 N on the moon”

This statement is correct because of the weight changes with a place. It depends on the acceleration due to gravity at that place. The acceleration due to gravity on the surface of the moon is about that on the surface of the earth. Hence the weight of the astronaut on the moon should be about that on the surface of the Earth.  of 840 N is 140 N.

An object is weighed in the following places using a spring balance. At which place will it weigh the heaviest.

a) on the moon b) at the equator c) at the poles d) in space

• The acceleration on the surface of the moon is about that on the surface of the earth. Hence the weight of the astronaut on the moon should be about that on the surface of the Earth.
• On the earth itself, the acceleration is not the same everywhere. It is the highest at poles and the lowest at the equator. Thus on the surface of the earth, the weight of a body is more at poles than that at the equator.
• In space the acceleration due to gravity is negligible. Thus the weight of a body in the space is negligible i.e. almost zero. Thus the body will weigh the heaviest on the poles of the Earth.

Example – 01:

An object placed on an equal arm balance requires 12 kg to balance it. When placed on a spring scale, the scale reads 12 kg. Everything with measuring setup is transported to the Moon where free fall acts one-sixth that on the Earth. What will be the new readings of the equal-arm balance and the spring scale?

Explanation:

When we use beam balance we compare the weight of body with standard weights. Thus on the moon also the process is that of comparison. Hence the equal arm balance will show the same reading as that on the Earth i.e. 12 kg.

When we use spring balance we actually measure the weight of the body. The weight of a body at a place depends on the acceleration due to gravity at that place. On the Moon, the free fall acts one-sixth that on the Earth. i.e. the acceleration due to gravity on the surface of the moon is about that on the surface of the earth. Hence the weight of the body on the moon should be about that on the surface of the Earth.  of 12 kg is 2kg (force).

Previous Topic: Measurement of Areas and Volumes

Next Topic: Measurement of Density

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In this article, we shall study methods of the measurement of area and volume.

Measurement of Area:

Measurement of Area of Irregular Shape:

The area of an irregular object can be obtained by drawing an outline of the shape of the object on a graph paper of 1 square centimeter marked square.

• The number of complete squares is counted.
• Next squares more than half are also counted as a complete square.
• Squares less than half are left and not counted.
• The sum of all the squares counted gives the area of the shape in square centimetres.
• In the above figure, the area of the shape is 51 square units.

Measurement of Area of Regular Shapes:

• Area of a triangle = 1/2 x base x height
• Area of a square = side²
• Area of a rectangle – length x breadth
• Area of a circle = π(radius)² =  π/4 x (diameter)²
• Area of a parallelogram = base x height
• Area of a rhombus = 1/2 x product of diagonals
• Area of trapezium = 1/2 x sum of parallel sides x Distance between parallel lines

Units of Area:

S.I. unit of area is m² and read as a square metre. c.g.s unit of area is cm² and read as square centimeters. Land areas are bigger hence the area of land is measured in a hectare. 1 hectare = 10000 m²

Numerical Problems:

Example – 01:

An artist designed two postage stamps. One was square and measured 2 cm X 2 cm. The other was rectangular and measured 3 cm X 2 cm. Before the stamp was issued, it was decided to double the length of each side of a square stamp and triple the length of each side of a rectangular stamp. By how many times will the area of the paper required for each stamp increase.

Solution:

Square Stamp:

Initial area of square stamp = 2 cm x 2 cm   = 4 cm².

New area of square stamp   = (2 x 2) cm x (2 x 2) cm = 16 cm².

The area of the paper for square stamp will increase by (16 cm²/4 cm²) 2 times

Rectangular Stamp:

Initial area of rectangular stamp = 2 cm x 3 cm = 6 cm².

New area of rectangular stamp = (3 x 2) cm (3 x 3) cm = 54 cm².

The area of the paper for rectangular stamp will increase by (54 cm²./6 cm²) 9 times

Example – 02:

The length of a school compound is 500 m and the breadth is 120 m. Find the area of the school in hectares.

Solution:

Area = Length x Breadth = 500 x  120 =  60000 m²

Now 1 hectare = 10000 m²

The area of school = (60000 m² / 60000 m²) = 6 hectares,

Measurement of Volume:

Volume is the space occupied by an object. The S.I. unit of volume is m³. Its c.g.s. unit is c.c. i.e cm³. Other practical units are millilitre (ml), litre (l) etc. The volume of regular bodies can be obtained by measuring the necessary dimensions for the calculation of the volume.

Measurement of Volume of Regular Solids:

• Volume of rectangular parallelepiped = length x breadth x height
• Volume of cube = side³.
• Volume of cylinder = πr²h
• Volume of cone = 1/3 x πr²h

Volume of Liquids:

Measurement of volume of a liquid is done using the following apparatus

Measuring Jar:

It is a graduated glass jar marked in ml from bottom to top. It is used to measure required amount of liquid.

Measuring Flask:

It has one mark etched at the neck and the liquid of the only volume of its capacity can be measured.

Pipette:

It is filled by sucking the liquid into it. It is used to take a fixed amount of liquid.

Burette:

It is a tube similar to measuring jar, with a pitch cock provided at the bottom. It is used to take the desired amount of liquid.

Precaution: Read from the bottom of the curved surface of the liquid called meniscus.

Measurement of volume using Measuring jar by the direct method:

Pour the liquid in the measuring jar carefully and fill the jar with liquid as per the required quantity by reading the meniscus of the liquid in the measuring jar.

Measurement of Volume of Irregular Solids:

Solid Insoluble in Water but Heavier Than Water:

• Take some water in the measuring jar. Note the volume V₁ cm³ of this water.
• Immerse the solid carefully and completely in water.
• Note the volume V₂ cm³ of water with solid in it.
• Calculate increase in volume = V₂ – V₁
• Then volume of solid = (V₂ – V₁) cm³.

Solid Insoluble in Water but Lighter Than Water:

• For this sinker (heavy body) has to be used.
• Take some water in the measuring jar. Note the volume V₁ cm³ of this water when the sinker is in water.
• Tie sinker to the solid and immerse the solid with the sinker carefully and completely in water.
• Note the volume V₂ cm³ of water with solid and sinker in it.
• Calculate increase in volume = V₂ – V₁
• Then volume of solid = (V₂ – V₁) cm³.

Note: For solids soluble in water a liquid other than water, in which the solid is insoluble is used.

To Find Average Volume of a Single Drop of water:

• Take clean burette with water. Clamp it upright. Remove any air bubbles formed.
• Now allow the water to trickle slowly drop by drop in measuring jar.
• Count the number of drops collected in the measuring jar.
• Measure the volume of water in the measuring jar and use the following formula to find the volume of a drop of water.
• Volume drop = Volume of water collected / No. of drops

To Find Average Volume of Lead Shot:

• Take some water in the measuring jar. Note the volume V₁ cm³ of this water.
• Drop ‘n’ numbers of lead shot in the measuring jar carefully.
• Note the volume V₂ cm³ of water with lead shots in it.
• Calculate the increase in volume = V2 – V1
• The volume of each drop = Increase in volume / No. of lead shots (n)

Numerical Problems:

Example – 03:

A stone X is immersed in water taken in a measuring jar. The water level rises from 60 cm³ to 78 cm³. If a second stone Y is immersed in water, the level rises from 60 cm³ to 86 cm³. What is the rise in the level of water when stone X and Y are immersed simultaneously? What is reading in the measuring jar?

Solution:

Volume of stone X = 78 cm³ – 60 cm³ = 18 cm³.

Volume of stone Y = 86 cm³ – 60 cm³ = 26 cm³.

Total Volume of stone X and stone Y = 18 cm³ + 26 cm³ = 44 cm³.

Rise in the level of water in measuring flask = 44 cm³.

The level of water in the measuring jar after immersing both the stones = 60 cm³ + 44 cm³ = 104 cm³.

Rise in the level of water in measuring flask = 44 cm³ and Reading of measuring jar = 104 cm³

Example – 04:

Two identical lead balls are immersed into a measuring jar containing water, the level of water raises from 16 cm³ to 26 cm³. If one of the above lead ball and another metallic ball are immersed simultaneously, then the level of water in measuring jar raises from 20 cm³ to 40 cm³. Find the volume of the lead ball and metallic ball.

Solution:

Volume of two lead balls = 26 cm³ – 16 cm³ = 10 cm³.

Thus, volume of each lead ball = 10 cm³/2 = 5 cm³.

Volume of one lead ball + Volume of metallic ball = 40 cm³ – 20 cm³ = 20 cm³.

Volume of metallic ball = 20 cm³ – Volume of one lead ball = 20 cm³ – 5 cm³ = 15 cm³

Hence the volume of lead ball is 5 cm3 and that of metallic ball is 15 cm³.

Example – 05:

When 20 drops of water are allowed to collect in a measuring jar containing water, the level of water raises from 26 cm³ to 28 cm³. Find the average volume of each drop.

Solution:

Volume of 20 water drops = 28 cm³ – 26 cm³ = 2 cm³.

Volume of each drop = Volume of 20 water drops / 20 = 2 cm³ / 20 = 0.1 cm³

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