Matter and its composition

Question 1

Three properties that define any object as matter

Answer 1

a) occupies space, b) has mass and c) may be percieved by our senses

Question 2

Energy (small definition)

Answer 2

Capacity to do work

Question 3

4 characteristics of particles and experiments to describe.

Answer 3

a) are extremely small (diluting a solution with colorful substances), b) Have spaces between and within them (salt and water solution volume does not increase), c) are constantly moving, d) attract (not sure but probably may repel as well) each other (water particles stick togetheras droplets)

Question 4

Unit of size of particles

Answer 4

10^-9 or nano

Question 5

Example of brownian motion, and diffusion

Answer 5

Dust in air, pollen particles on water, diffusion of colorful substances ink in water. or colorful bromine vapors or chlorine in air.

Question 6

Properties that describe matter in states

Answer 6

Forces of attraction, interparticle space(compression can be checked), kinetic energy of particles due to their attraction, (fluid, fixed or non-fixed volume),

Question 7

Solid to liquid

Answer 7

On heating. Melting. Melting temparature. Can be recognized by fluidity and at molecular level the molecules can move from their position (solids still have motion but stay within a particular area)

Question 8

Liquid to Gas

Answer 8

Boiling, on heating. Boiling Temparature. Can be recognised by compressing or providing excess space to check volume changes, maximum intermolecular space,. Diffuse in liquids.

Question 9

Why do states change?

Answer 9

Difference in the kinetic energy and the intermolecular forces makes a difference in how close the particles are kept. Heat and pressure can cause affect the kinetic energy of the particles.

Question 10

What is latent heat?

Answer 10

Latent heat is the energy used up to change from one state to another. Normally, this application of heat to a material would heat the material up, but when changing states the heat is required to change the state is not visible on the thermometer, and thus is ‘latent’ or hidden.

Question 11

How can air be liquefied?

Answer 11

Gas can be changed into liquid(then solid) by applying pressure. [Liquefication]
LPG or Liquefied Petroleum Gas is used as refrigerants and aerosol sprays to replace CFCs in damaging the ozone layer, fuel for vehicles and as cooking gas.
(See PV graphs, Pressure-Volume)

Question 12

What is critical temparature?

Answer 12

Critical temparature is a term in liquefaction, above which a gas would not liquefy when pressurised, but would still have density. CO2 has the critical temparature of 31 degrees Celsius.
There is also a critical pressure.

Question 13

Equilibrium (states of matter)

Answer 13

If a substance is in a closed container at the boiling point, then the liquid is boiling and the gas is condensing at the same rate without net change in their relative amount. Molecules in the liquid escape as a gas at the same rate at which gas molecules stick to the liquid, or form droplets and become part of the liquid phase. The combination of temperature and pressure has to be “just right”; if the temperature and pressure are increased, equilibrium is maintained by the same increase of boiling and condensation rates.

Question 14

Example of equilibrium (ice cubes, pressure cooker)

Answer 14

A cup of water (or soda) with ice cubes stays at 0ºC, even on a hot summer day
The ice and liquid water are in thermal equilibrium, so that the temperature stays at the freezing temperature as long as ice remains in the liquid. (Once all of the ice melts, the water temperature will start to rise.)

Water and steam stay at a point of equilibrium in a pressure cooker, which allows food to be cooked faster. The proportionality between temparature and pressure to maintain the equilibrium state causes change in temparature.

Question 15

What is vapor? When is a gas considered as vapor?

Answer 15

A substance in gaseous state below it’s boiling point is known as vapor.
A gas is considered to be one if it is at the gaseous state in normal conditions, but vapor when the substance normally exists is any other form.

Question 16

What defines a fluid?

Answer 16

A fluid is a substance that continually deforms (flows) under an applied shear stress, or external force.
Plasma is a fluid, liquid forms a free surface and gas does not.
Fluids cannot resist force applied to them.

Question 17

Is there any change in mass when a substance changes its state?

Answer 17

No, due to the conservation of mass, which is also applied in chemistry.

Question 18

Kinetic Theory of Matter (short)

Answer 18

Any substance which is made up of particles (atoms, molecules or ions) are in constant motion. [A theory]

Question 19

The constituent particles of any given substance are _______ .

Answer 19

Identical in all respects.

Question 20

Postulates of kinetic Theory (6), Can be used to create Kinetic models that differ between states.

Answer 20

1. Composition of matter (Particles which are identical in all respects)
2. Arrangement of particles (have inter-particle spaces)
3. Force of attraction (inter-particle attraction, depends on space and magnitude/size)
4. Collision of particles (Total energy of colliding particles remain the same)
5. Motion (Always in a state of motion)
6. Energy possessed by matter (Have kinetic energy or the internal chemical energy of a substance)

Question 21

Plasma

Answer 21

Plasma is superheated matter – so hot that the electrons are ripped away from the atoms forming an ionized gas.
The gas contains ionized particles and free electrons.

Plasma is considered as the most abundant state of matter (in stars and without understanding dark matter)
Plasma tends to glow, as the excited energy of the particles is high enough to produce energy in the form of light due to collisions.

Question 22

5th state of matter

Answer 22

Bose- Einstein Condensate(BEC), formed by extreme cooling of a gas, to one hundreth-thousandth of the density of normal air.

Question 23

In which direction does melting occur?

Answer 23

From the outside/surface towards the inside. Probably because the fact that heat would be more dispersed as it travels further and source is closest to the surface.

Question 24

Why does ice lower the freezing point of water?

Answer 24

In the state of equilibrium of matter, the water molecules simultaneously get loose and stick onto the surface of the ice. For the salt molecules present in the water, the salt bounces off the surface of the water instead of sticking of water, hence delaying the freezing.
The salt or solvent molecules interrupt the process of freezing and thus more amount of heat is required to be removed in order for the intermolecular forces to increase considerably, enough to make a solid with the solvent particles.

Question 25

Variables that affect rate of evaporation (5)

Answer 25

• > Surface area
• > Temparature
• > -Humidity
• > -Pressure
• > Wind speed.

Question 26

In what direction on a liquid does boiling occur?

Answer 26

From all sides and areas of the liquid, which makes it different from evaporation that occurs from the surface of the liquid.

Question 27

What are the physical properties of matter? Mention the properties (11+)

Answer 27

Physical properties are those that can be either felt by the senses or measured with the help of proper equipmen. The identity of a substance does not change when finding the physical properties of a substance.

1) State, 2) color, 3)odour, 4) taste, 5)solubility, 6)density, 7)hardness, 8) Rigidity, 9) conductivity (thermal and electrical), 10) melting and boiling points, 11) Magnetic properties.

Question 28

FYR

Answer 28

• All properties of matter are either physical or chemical properties and physical properties are either intensive or extensive.
• Extensive properties, such as mass and volume, depend on the amount of matter being measured.
• Intensive properties, such as density and color, do not depend on the amount of the substance present.
• Physical properties can be measured without changing a substance’s chemical identity.
• Chemical properties can be measured only by changing a substance’s chemical identity.

Question 29

What are chemical properties of matter?

Answer 29

Measured by subjecting matter to chemical action, changes the chemical identity of the substance.

• Combustibility may undergo incomplete or complete or both types of combustion. May be a supporter of combustion (provides oxygen or substance to combust with another)
• Stability (on heating or otherwise)
• Extent on which it reacts with water, acids and alkalis.
• Relative reactivity
• Ionisation in water, and extent,
• Amount of heat released on combustion.
• Preffered oxidation state.
• Toxcity
• Radiation
• Allotropy
• pH

Question 30

Limitations of law of conservation of mass

Answer 30

Some amount, although very small amount of energy is lost in a reaction in the form of energy release. The law of conservation of mass is not strictly valid unless energy and mass is taken together.

Question 31

How does color affect absorbtion?

Answer 31

When a color (colored fabric) absorbs light, it turns the light into thermal energy (heat). The more light a color absorbs, the more thermal energy it produces. Black fabric absorbs all colors of light and is therefore warmer than white fabric which reflects all colors.

Question 32

Expansion examples

Answer 32

Railway tracks have spaces in between, Bridges have some stuff in between to allow for expansion, telephone and electrcity wires are kept lose to allow for contraction, a balloon bursts when kept in sun for a long time.