chemistry igcse 2 Flashcards

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1
Q

what is a kinetic particle theory

A
  • describes the states of matter
  • explains the differences in the properties of solids, liquids and gases
  • explains the changes of state of matter
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2
Q

why does a solid have a fixed shape

A

the particles of a solid are closely packed and are arranged in a regular arrangement. The strong forces of attraction holds the particles together. It has enough kinetic energy to vibrate and rotate in a fixed position. The particles cannot move freely.

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3
Q

why does a solid have a fixed volume

A

the particles of the solid are regularly arranged and are closely packed meaning that it cannot be compressed.

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4
Q

why does liquid not have a fixed shape

A

the particles of a liquid are arranged irregularly. They have weaker forces of attraction than the particles of a solid and are not held in a fixed position meaning that the particles can move freely through out the liquid.

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5
Q

why does liquid have a fixed volume

A

the particles of a liquid are packed quite closely together meaning that they cannot be compressed

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6
Q

why does gas not have a fixed shape

A

the particles of the gas a spread far apart and have a weaker force of attraction. They have more kinetic energy than both solids and liquid meaning that the particles can move freely and fast, therefore the particles are not held in fixed positions.

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7
Q

why does gas not have a fixed volume

A

there are a lot of space between the particles compared to the particles of a solid and a liquid. They can easily be compressed, therefore it does not have a fixed volume.

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8
Q

what is the process called when a solid turns into a liquid

A

melting

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9
Q

what is the process called when a liquid turns into a solid

A

freezing

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10
Q

what is the process called when a gas turns to a liquid

A

condensation

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10
Q

what is the process called when a liquid turns into gas

A

evaporation / boiling

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11
Q

what are the differences of boiling and evaporation

A

boiling only occurs at the boiling point which is 100 degrees celcius. Boiling occurs throughout the liquid and occurs rapidly. Evaporation happens at temperatures below boiling point, occurs only on the surface of the liquid and occurs slowly.

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12
Q

how does the kinetic particle theory explain the change of state of a solid to a liquid

A

when a solid starts to melt, the heat is absorbed by the particles of a solid, the particles will start to vibrate faster in their fixed positions. There is an increase in their kinetic energy.

when the temperature is high enough, the vibrations of the particles will soon overcome the attractions between them. The particles will soon break away from their fixed positions.

the particles will no longer be in fixed positions .he substance is now a liquid. The particles can move freely throughout the liquid.

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13
Q

how does the kinetic particle theory explain the change of state of a liquid to a solid

A

the energy is given out by the particles of the liquid. the particles lose kinetic energy and will begin to move more slowly.

when the temperature is low enough, the particles will no longer be able to move freely. they start to settle in their fixed positions.

all the particles have settled int their fixed positions. the substance is now a solid. the particles can only vibrate and rotate in their fixed positions.

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14
Q

how does the kinetic particle theory explain the change of state of a liquid to gas

A

heat is absorbed by the particles of a liquid. the particles will start to move faster as the temperature increases, there is an increase in the kinetic energy.

when the temperature is high enough, the particles have enough energy to overcome forces of attraction holding them together.

the particles are now spread far apart. the substance is now a gas. the particles can move about in any direction.

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15
Q

what is the effect of temperature on the volume of a gas

A

when a gas is heated, the temperature increases. the particles gain more energy, therefore the volume of the gas increases.

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16
Q

what is diffusion

A

the random movement of particles from a region of high concentration to a region of low concentration

17
Q

what the is effect of pressure on the volume of the gas

A

increase of pressure on the gas, the volume of the gas will decrease

18
Q

what is an element

A

a substance that cannot be broken down into any other smaller subtstances

18
Q

the experiment is held, a cotton will soaked in concentrated aqueous ammonia and a cotton wool soaked in concentrated hydrochloric acid, which one will diffuse faster?

A

the cotton wool soaked in concentrated aqueous ammonia will diffuse faster as it had a lighter relative molecular mass.

19
Q

what is an atom

A

the smallest particle of an element that has the chemical properties of that element

20
Q

what is a molecule

A

a group of two or more atoms that are chemically combined

20
Q

compositions and decompositions of an element

A

composition
- an element contains only one type of atom
- the smallest particle in an element is an atom

decomposition
- an element cannot be broken down into any other smaller substances

21
Q

what is a mixture

A

a mixture is made up of two or more substances that are not chemically bonded

21
Q

how do we measure the volume of a gas

A

use a plunger to push fully to expel any gas in the syringe, as the gas from an external source enters the syringe, it pushes the plunger outwards

22
Q

compositions and decompositions of a compound

A

composition
- a compound contains two or more elements that are chemically bonded
- the smallest particle in a compound is a molecule or an ion

decomposition
- a compound can be broken down into elements or simpler compounds by thermal decomposition

23
Q

what does solubility mean

A

how soluble the gas is in the water

24
Q

wha† does density mean

A

how dense the gas is compared to air

25
Q
A
25
Q

what are the methods for collecting gas

A
  • displacement of water
  • downward delivery
  • upward delivery
26
Q

what is a solution

A

a lqiuid mixture composed by two or more substances

26
Q

what is a solute

A

a solid particle that can dissolve in a liquid

27
Q

what is a solvent

A

a substance that dissolves the solute

28
Q

what is a residue

A

the impurities left after filtration, evaporatuin or distillation

28
Q

what is a saturated solution

A

a solution containing the maximum amount of concentration

29
Q

what is a filtrate

A

a liquid or a solution that is pure

30
Q

what is the purpose of paper chromatography

A

to see if a substance is pure or not

31
Q

what is a solvent front

A

the position reached by the solvent

31
Q

how can we tell if a substance is pure

A

when the ink or the substance is dissolved by the water, when only one colour is present the substance is pure

31
Q

what is the purpose of simple distillation

A

used to separate a pure solvent from a solution

32
Q

how do we find the rf value

A

rf= distance travelled by the substance / distance travelled by the solvent

33
Q

how do we obtain a solid from a liquid

A

evaporation to dryness