Matter Around Us

373K is equivalent to 100°C in celsius scale which is the boiling point of water so water takes in the latent heat of vaporisation at 373K and converts itself to gas(vapour) state.

Common salt, carbon dioxide and Pure silver are pure substances while juice is mixture of water, sugar, fruits and other ingredients. Another way of identifying is that, mixture do not have any formula, here we see that juice does not have any fixed formula while others have.

Ink does not dissolve into water uniformly and mixture has different composition at different point.

The constituents of the mixture are also known as components of the mixture.

Apart from pure substances, others have different ratio of elements as we move across that thing so they have different properties at different position while pure substances have same composition everywhere.

.

.

.

.

.

False

Butter from milk can be separated by centrifugation.

True

True

False

Liquid – liquid colloids are called emulsions.

True

Alcohol can be separated from water by Fractional Distillation.

Sand is removed from naphthalene by a Sublimation method.

In petroleum refining, the method of separation used is Fractional distillation.

Chromatography is based on the principle of different solubility of the solute in the same solvent.

The solubility of solid in water increases with an increase in temperature.

Using the process of sublimation we can separate mixture of ammonium chloride and common salt since ammonium chloride sublimes on heating and changes to its vapour form while common salt does not.

Solute: Substance (solid, liquid and gas) which is dissolved in another substance is known as solute.

Solvent: The substance on which solute is dissolved is solvent.

E.g in the salt solution, salt is solute and water is solvent and together they make solution.

i) Iodine since it sublimes and changes to its vapour state on heating which then can be cooled to again get back the iodine.

ii) Ammonium chloride since it t sublimes and changes to its vapour state on heating which then can be cooled to again get back the Ammonium chloride.

Desalination of sea water implies taking out salt and other vital minerals from sea water.

Adsorbate: Substance which get adsorbed (atoms or ions of the substance get attached to other surface by adhesive force) on the adsorbent.

Adsorbent: Substance on whose surface substance gets adsorbed. Its concentration is high.

Rf is known as Retardation factor. It is helpful in chromatography.

Rf = Distance moved by the solute/Distance moved by the solvent.

Here distances are measured from the common origin.

i) For separating miscible liquids we use fractional distillation method in which we use fractionating column (long vertical glass tube) and distillation flask.

ii) For separating immiscible liquids we use separating funnel (funnel with stop cock at its top)

Mixture containing saw dust, napthalene and iron filling can be separated as follows :

a) We bring magnet near the mixture as a result iron filling get attracted to it and we are left with saw dust and napthalene.

b) Now we adopt the process of sublimation and heat the given mixture gently then napthalene sublimes which then can be collected by cooling and sand dust is left behind.

Common salt has polar nature (actually ionic) and water is a polar solvent whereas oil is non-polar so salt gets dissolved only with water. (Like dissolves like)

a) We know that oil and water are immiscible liquids and salt is dissolved only in water so we make use of separating funnel. Water along with dissolved salt is present in the lower layer while oil forms the upper layer. On opening the stop-cock, water runs out while oil remains which can then be removed.

b) Now, water boils at 100°C while common salt doesn’t so they can easily be separated with boiling or vaporisation technique.

Forensic science is the way of utilising science in catching the criminals in our society.

Application of chromatography in forensic science:

a) The blood samples that are recovered from the crime scene.

b) chromatography is used to analyze the explosive material.

c) It is helpful to analyze whether content written is using the same ink or different ink.

d) It is used to catch the suspect of stealing the money by mixing the money with the dye and then analyzing it using chromatography.

Two separating techniques used there are

a) Centrifugation : To obtain cream from raw milk. A rotating machine knowns as centrifuge is used.

b) Evaporation : After getting raw milk from farmers, it is evaporated so as to get its condensed form which is then mixed with small amount of sugar and packed in can.

Y is denser. One example for X is kerosene and one example for Y is water. Third liquid Z is alcohol (ethanol) which is soluble in water. We will observe two layers.

Now we will employ the process of fractional distillation since every liquid has different boiling point.

Upon taking them in fractionating column, first the liquid with least boiling point will evaporate and will be collected as pure compound and then the next one and in this we can separate all three liquids.

C

In the process of filtration we separate solids from the liquids in which they are insoluble. So the components that is unable to pass funnel is residue while one that has successfully passed is filtrate.

(a) False

Gases expand more than liquid on heating since they have more intermolecular space as compared to liquid so on heating the molecules in gases gets more space to increase in size as compared to molecules in liquid.

(b) False

Compound breaks down into simpler substance during chemical change such as when heat is supplied to calcium carbonate which is compound breaks down into simpler substances which are the constituents of it.

(c) False

The boiling point of water depends upon the surrounding pressure since at boiling point, vapour pressure of the gas coming out of the liquid equals the pressure on it because of environment. So as we move up, pressure drops as a result boiling point decreases similar is the case with melting point.

(d) True

Butter and milk are immiscible into one another and a layer of butter can be seen clearly at the top.

(e) False

Aspirin is composed of 60% Carbon, 4.5% Hydrogen and 35.5% Oxygen by mass. Aspirin is a compound.

Aspirin has fixed proportion of carbon, hydrogen and oxygen combined in the ratio of their mass. So it has fixed formula and hence it cannot be mixture as mixture has no formula.

i) Element –Pure substance

ii) Compound - Made up of atoms

iii) colloid – made up of molecules

iv) Suspensions - Settles down on standing

v) Mixture - Impure substance

Evaporation is always accompanied by decrease in temperature.

150°C = 423K

A Homogeneous mixture has no distinguishable boundary between its components.

An example of a substance that sublimes is camphor.

Latent heat is the energy used for changing state of the substance.

It is possible to row a boat in water as it has some spaces between its molecules so when we place boat over water, it displaces some amount of water and water displaced provides it necessary buoyant force.

Wooden fence is solid in state and has no space so it is impossible to pass through it.

We know that gases have large amount of intermolecular spaces and they move freely in random direction so when we fill any container with gas then the gas molecules collides with the wall of the container and apply some force on the wall of the container and in this way gases exert pressure on the container.

Sublimation is the process in which solid directly changes to its gaseous state upon heating without passing through its liquid state.

Gaseous/Vapour state has the highest kinetic energy since in this state the intermolecular space is more and molecules have lots of space to move and since kinetic energy is due to the movement/motion of the particles, hence it has highest kinetic energy.

Turbid means Cloudiness. Dettol and water are immiscible with one another and form emulsion so when we mix them dettol particles get suspended in water and scatter white light . Therefore it appears turbid.

Gases are easily compressible since they have lot of spaces between its molecules (intermolecular space) so when we apply pressure during compressing, the molecules gets room to move from its original position while in case of solids, molecules are very close to each other and have almost no intermolecular space to move when we apply pressure on them.

Yes, we can compress it. We know that smiley ball is solid in state yet it can be compressed since it has tiny pores in it, in which air resides so when we squeeze it, air is driven out and in this way we are able to compress it.

Hydrochloric acid, mercury, Ice, Iron and Water are pure substances since they are made up of one or more than one atom of its kind. Also they have their fixed formula while in case of milk (mixture of butter, milk and other ingredients) and brick (mixture of clay, sand etc), they are made by mixing ingredients whose ratio is not fixed. Also they do not have fixed chemical formula.

An element has fixed symbol and is made up of only one atom of its kind. Since Oxygen has fixed symbol (O₂) and is made up of only one atom of its kind (2 O merge together to form oxygen) it is an example of element.

It is an impure substance since the purity of gold is measured in terms of carat. 24 carat is the pure form of gold so 22 carat gold = (22/24) ×100 = is 91.66 % pure only. It is actually alloy of gold, silver and nickel.

Tyndall effect : It is the effect in which the light is scattered due to colloidal particles in its path as a result path of light becomes visible.

In the figure shown above, the first solution is plain water which does not exhibit Tyndall effect while the second one is a colloidal solution which shows Tyndall effect as the path inside it becomes visible due to scattering of the light by the colloidal particle.

Brownian Motion: Upon dropping some tiny particles in the fluid and observing it with a microscope, we see the zig-zag movement of the particles which occurs due to the collision with the particles of the fluid. This phenomenon is known as

Brownian movement of the particles. Below figure depicts the erratic movement of the particles inside the fluid.

Model described below describes one of the important characteristics of the particles in a solid, liquid and gas.

Steps :

a) Take a beaker filled with more than half of water.

b) Put some copper sulphate at the bottom of the beaker.

c) Keep it for some time.

Observation :

After few minutes, we notice that whole solution turned blue.

Reason :

Initially, copper sulphate was placed at the bottom of the beaker. Particles of the copper sulphate start moving randomly in all direction and collide with the water particles since water particles are colourless and copper sulphate is blue in color so the particles of the copper sulphate imparts blue color to the whole solution.

Conclusion:

Particles of solid, liquid and gas are constantly moving.

Bottle of the medicine such as cough syrup is colloidal mixture that comes under category of emulsion in which liquids immiscible with one another are taken together.

It is advised to shake the contents of the bottle as particles inside the bottle settle down after sometime so in order to mix well the particle thoroughly so that its composition becomes same throughout.

Steam produces more severe burns as compared to boiling water.

Reason: We know that water boils at 100°C and for converting to steam at 100°C it takes the latent heat of vaporization so steam has more heat than boiling water which is the latent heat which causes more severe burns than boiling water.