Topic 1: Safety, States of Matter and Separation techniques

Question 1

the arrangement, movement and energy of the particles in a solid

Answer 1

-strong forces of attraction which holds them close together in a fixed positions in a lattice arrangement
- the particles dont move, they keep a definite shape and volume and dont flow
-the particles vibrate about their positions(more as they gain temperature, making them expand slightly)

Question 2

the arrangement, movement and energy of particles in a liquid

Answer 2

-weak forces of attraction. randomly arranged and free to move over each other but tend to stick together.
-have a definite volume but flow to fill the bottom of a container
- particles are constantly moving with random motion. the hotter the liquid gets the faster they move, which causes the liquid to expand slightly.

Question 3

the arrangement, movement and energy of particles in a gas

Answer 3

-the force of attraction is very weak between particles. they are free to move and are far apart. the particles travel in strait lines.
-dont keep a definite shape or volume and will always fill any container.
- the particles move randomly with random motion. the hotter the gas gets, the faster the particles move. gases expand when temperature or pressure increases

Question 4

change from liquid to solid

Answer 4

freezing
- decrease in temp
- decrease in kinetic energy
- particles move less, and form bonds

Question 5

change from gas to liquid

Answer 5

condensing
- decrease in temp
-decrease in kinetic energy
-particles lose energy and move less

Question 6

change from solid to liquid

Answer 6

melting
-increase in temperature and kinetic energy in particles
-particles vibrate more and then they have enough energy to weaken their bonds and break from their positions

Question 7

change from liquid to gas

Answer 7

evaporating
- increase in temp and kinetic energy in particles
-particles move faster and weakens and breaks the bonds holding the liquid together.
- at a certain temp, they fully break their bonds and turn into a gas.

Question 8

change from solid to gas

Answer 8

sublimation
-increase in temp and kinetic energy between particles
- skip the liquid faze and turn strait to gas by breaking their bonds with enough energy

Question 9

change from gas to solid

Answer 9

deposition
-decrease in temp and kinetic energy between particles
-skips the liquid phase and turns strait to a solid by creating bonds between particles.

Question 10

dilution of coloured solutions practical

Answer 10

Potassium manganate(VII) and water
-potassium crystals added to beaker of water.
-the purple colour spreads out by diffusion out among the particles of water.
- this is caused by the random movement of particles in water.
-more water added would lead to the purple particles to spread out more, this is called dilution

Question 11

diffusion experiments

Answer 11

Ammonia and hydrogen chloride
-put cotton wool soaked in aqueous ammonia at one end of a sealed glass tube and cotton wool soaked in hydrochloric acid at the other end.
- a ring of ammonium chloride forms between them.
the ring isnt in the middle because of the slower diffusion rate of the hydrochloric acid

Bromine in air
- put bromine gas(brown) in a half a test tube, separated by a glass plate.
remove the glass plate and the gas will diffuse evenly through the rest of the tube becuase of the particles random motion.

Question 11

what is a solvent

Answer 11

the liquid something is dissolving into

Question 11

what is a solute

Answer 11

the substance being dissolved

Question 12

what is a solution

Answer 12

the mixture of solute and solvent that does not separate out

Question 13

what is a saturated solution

Answer 13

a solution where the maximum amount of solute has been dissolved, so no more solute will dissolve in the solution

Question 14

what is an atom

Answer 14

an atom is a single element made up of protons, neutrons and electrons.

Question 15

what is a molecule

Answer 15

a molecule is a group of atoms.

Question 16

what is an element

Answer 16

an element is a single type of atom

Question 17

what is a compound

Answer 17

a substance made up of two or more different elements chemically bonded together e.g. carbon dioxide

Question 18

what is a mixture

Answer 18

a substance made up of two or more different elements not chemically bonded together.
the element can be separated through different methods

Question 19

what is simple distillation

Answer 19

• used for separating a liquid from a solution.
• the solution is heated and the part with the lowest boiling point evaporates.
• the vapour is collected and cooled in a condenser, then collected in a beaker
• the rest of the solution is left behind in the flask

Question 20

what is fractional distillation

Answer 20

this is used to seperate a mixture of liquids
- the mixture is put in a flask and a frationing column is put on top.
- the liquid with the lowest boiliong point will evaporate and reach the top of the column first.
-liquids with a higher boiling point will also evaporate but the column is a lower temp than the flask so they will condense and run back down into the flask.
- you can increase the temp to separate the liquids one by one.

Question 21

what is filtration

Answer 21

filttration is used to separate an insouble solid from a liquid

Question 22

what is crystallisation

Answer 22

crystallisation separates a soluble solid from a solution
-evaporate of some of the water by heating to concentrate the solution
-leave the solution to cool
- crystals should form as it becomes insoluble in the cold solution.

Question 23

what is paper chromatography

Answer 23

paper chromatography is used to separate out dyes.
the different dyes travel different length up the paper with the water and separate out

Question 24

how can information from chromatograms be used to identify the composition of mixtures?

Answer 24

you can calculate an Rf value to see if a ceratin substance is present in a mixture by comparing it to other Rf values

Question 25

how to use the calculation of an Rf value ot indentify components?

Answer 25

Rf=distance travelled by solute
—————————————–
distance travelled by solvent

compare Rf values to check the identities of its components