Science Chemistry Revision Tests (HALF term)

What is the name of the piece of paper at the end of a chromatography experiment?

chromatogram

Crude oil can be separated into several liquids that have different boiling points. What is the name of this process?

fractional Distillation

What charge does a neutron have?

0 (neutral)

What year was the year the periodic table created in?

1869

What state is something when it is above the boiling point?

It is a Gas

What state is something when it is between the melting point and the boiling point?

It is a liquid.

What state is something when the temperature is below the melting point?

It is in the solid state.

Where would the most soluble pigment be on chromatography paper?

It will be higher up the paper.

Which theory describes the arrangement and movement of particles in solids, liquids and gases?

Kinetic Theory.

What charge does a proton have?

+1 (Positive)

What charge does an electron have?

-1 (Negative)

What can cause a gas to liquefy?

A gas will also liquefy if its pressure is increased enough. This is because the particles are moved close enough for bonds to form between the particles.

What is a hazard?

A hazard is something that can cause harm, e.g. electricity, chemicals, working up a ladder, noise, a keyboard, a bully at work, stress, etc

What is a mixture?

A mixture contains elements and/or compounds that are NOT chemically joined together. You can use a physical process to separate a mixture into different substances.

What is a pure substance?

A pure substance has the same fixed composition in all its parts and so we can't separate it into other substances using physical methods.

What is a risk?

A risk is the chance, high or low, that any hazard will actually cause somebody harm.

What does soluble mean?

A substance that can be dissolved.

Fractional distillation of crude oil - 1

A tall fractionating column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with lower boiling points condense on the way to the top.

What is crystallisation?

An experimental technique that is used to separate a solution. Boil the solution until crystals start to form and remove from heat.

What is an isotope?

Atoms of the same element that have different numbers of neutrons

Why do solids have a fixed shape and cannot flow?

Because the particles cannot move form place to place because of the particle bond which is strong.

Fractional distillation of liquid air - 2

Carbon dioxide freezes at -79ºC, and is removed

What is chlorination in Sedimentation?

Chlorination - Chlorine gas, injected into the water, kills microbes and micro organisms

Describe the process of Sedimentation - 3

Chlorination - The water moves to a separate section where Chlorine gas is injected to kill micro-organisms and make it safe to drink. Then is stored and delivered to homes and places.

Which method is usually used to separate coloured substances from each other?

Chromatography.

Fractional distillation of crude oil - 2

Crude oil is a mixture of hydrocarbons. The crude oil is evaporated and its vapours condense at different temperatures in the fractionating column. Each fraction contains hydrocarbon molecules with a similar number of carbon atoms and a similar range of boiling points.

What is it called when a gas turns straight into a solid?

Deposition

Which is the best way to get salt from salty water?

Distillation

Who made the first periodic table?

Dmitri Mendeleev

What are the shells of an atom?

Electrons

Gas movement of particles:

Fast in all directions Collision

Describe the process of Sedimentation - 2

Filtation- The water is then moved to a filtration tower, where the sediment settles at the bottom (eg: mud, soil, rocks.).

What type of solids does filtration separate ?

Filtration can only separate insoluble solids.

What is the name of the change when a liquid becomes a solid?

Freezing

Describe the process of Sedimentation - 1

From the water source to the sedimentation tank. A chemical is added to make solid particles join to make larger particles which can be filtered out or settled at the bottom

Describe the changes that happen to particles during the Boiling process.

If a liquid is heated the particles are given more energy and move faster. The most energetic particles at the surface escape from the liquid as a vapour as it gets warmer. Liquids evaporate faster as they heat up and more particles have enough energy to break away. The particles need energy to overcome the attractions between them. Eventually even particles in the middle of the liquid form bubbles of gas in the liquid. At this point the liquid is boiling and turning to gas. The particles in the gas are the same as they were in the liquid they just have more energy

What are immiscible liquids?

Immiscible means that the liquids don't dissolve in each other - oil and water are an example. It is possible to shake up the liquids and get them to mix but they soon separate.

Describe the difference in the arrangements of particles in a solid and a liquid.

In a solid, they are arranged in an orderly fashion and vibrate on the spot, they do not change shape, unlike a liquid that flows to fill the shape of a container. The particles in a liquid are randomly arranged and are still touching/close together.

What do isotopes have the same of and different of?

Isotopes have the same atomic number but different mass numbers.

Why is it not efficient to carry out distillation on large scales?

Large scale distillations are not efficient because they would use too much energy to get the liquid to boiling point and heat it which would be wasteful. As well as this, it would take much longer to carry out. An alternative for this could be sedimentation.

In which state of matter are the particles mostly touching but arranged in a random way?

Liquids

Liquid movement of particles:

Move around each other

Fractional distillation of liquid air - 4

Nitrogen liquefies at -196ºC

Is water pure once it has gone through distillation?

No, it is not pure water.

Can atoms and molecules be seen?

No, they are far too small and can normally only be seen under a microscope or not at all.

Fractional distillation of crude oil - 3

Note that the gases leave at the top of the column, the liquids condense in the middle and the solids stay at the bottom.

In chromatography, where are the spots of coloured substances placed?

On a vertical line at the bottom of the paper.

Fractional distillation of liquid air - 3

Oxygen liquefies at -183ºC

What kind of change are 'State Changes'?

Physical Changes, because they can be physically changed.

What two subatomic particles have the same value?

Protons = Electrons

How do you calculate an RF value?

RF Value = distance moved by compound(dot) / distance moved by solvent.

Liquid Arrangement of particles

Random Close together (touching)

Gas Arrangement of particles :

Random Far apart

Solid arrangement of particles

Regular Close together Organaized

Describe how you would use chromatography to separate dyes found in ink...

Simple chromatography is carried out on paper. A spot of the mixture is placed near the bottom of a piece of chromatography paper (2cm)and the paper is then placed upright in a suitable solvent, eg water. As the solvent soaks up the paper, it carries the mixtures with it. Different components of the mixture will move at different rates.

Why is it useful for a substance to sublime?

Solid --> Gas. It is useful because it is faster this way for the solid to turn straight into the gas, rather than having to melt and boil it which will take up more time.

Three states of matter:

Solid, Liquid, Gas

Whats the difference in how much kinetic energy each state of matter has?

Solids have the least kinetic energy, gases have the most kinetic energy which causes them to collide. liquids have less kinetic energy than gases and more than solid do.

What is it called when a solid turns straight into a gas? (Skips liquid stage)

Sublimation

There is the same amount of protons and electrons

TRUE

Explain what happens to the particles when a substance melts...

The closeness, arrangement and motion of the particles in a substance change when it changes state. When the liquid is heated, its internal kinetic energy increases: the movement of its particles increases. Bonds between particles break when a substance melts.

Fractional distillation of liquid air - 5

The liquid nitrogen and oxygen are then separated by fractional distillation.

What does the mass number tell you and where is it on a symbol?

The mass number is the total number of protons AND neutrons, you just have to subtract the atomic number to find the number of neutrons. The mass number is at the top of the symbol.

Describe the difference in the movement of particles in a liquid and in a gas.

The movement in a gas is free moving, and fast in all directions, unlike a liquid where they move around each other.

Describe the changes that happen to particles during the condensing process

The particles in a gas have different energies. Some may not have enough energy to remain as separate particles, particularly if the gas is cooled down. They come close together and bonds form between them. Energy is released when this happens. This is why steam touching your skin can cause scalds: not only is the steam hot, but energy is released into your skin as the steam condenses.

Melting Point definition

The temperature at which a given solid will melt and turn into a liquid.

Boiling point definition

The temperature at which a liquid boils and turns to vapour.

How can you tell when something is changing states on a graph? Why?

The temperature will stay constant and 'plateau' on a flat line, this is because the substance is using the energy to change the state of it. In a solid, the energy is used to break away from the energy.

What is filtration in Sedimentation?

The water is sprayed onto specially prepared layers of sand and gravel. As it trickles through, different sized insoluble solids are removed. The filter beds are cleaned periodically by pumping clean water backwards through the filter.

Why can solids and liquids not be compressed?

They cannot be compressed because the particles are close together and have no space to move into.

How do you calculate an RF Value.

Use a ruler to measure the distance from the solvent. Then measure the specific dot you would like to, and then divide the distance from the bottom line to the dot, divided by the distance travelled by the solvent.

Solid movement of particles:

Vibrate about in fixed positions

Fractional distillation of liquid air - 1

Water vapour condenses, and is removed using absorbent filters

What is deposition?

When a gas turns straight into a solid.

Describe the changes that happen to the particles during the melting process.

When a solid is heated the particles gain energy and start to vibrate faster and faster. Initially, the structure is gradually weakened which has the effect of expanding the solid. Further heating provides more energy until the particles start to break free of the structure. At this point, the solid is melting to form a liquid. The particles in the liquid are the same as in the solid but they have more energy. To melt a solid, energy is required to overcome the attractions between the particles and allow them to pull them apart.

What is sublimation?

When a solid turns into a gas

Can the physical changes of state be reversed? Why?

Yes, they can be because the particles themselves do not change, only their arrangement, movement and amount of stored energy(Kinetic)

What is a pure substance?

a substance in which there is only one type of particle

Laboratory water must be free from...

all impurities.

What is the mass number?

protons + neutrons

What is in the nucleus of an atom?

protons and neutrons

In filtration, what name is used to describe the solid left in the filter paper?

residue

What is fractional distillation?

separation of a liquid mixture into fractions differing in boiling point (and hence chemical composition) by means of distillation, typically using a fractionating column.

Tap water must be free from...

substances harmful to the health

What is the atomic number?

the number of protons in an atom