States of Matter and Mixtures Flashcards
Topic 2
What is the process of solids becoming liquids
Melting
What is the process of liquids becoming solids
Freezing
What is the process of liquids becoming gases
Boiling
What is the process of gas becoming a liquid
Condensing
Describe the particle arrangement of a solid (3 points)
- Strong forces of attraction between particles
- Contains a regular lattice structure
- Low energy causes particles to vibrate in position
Describe the particle arrangement of a liquid (3 points)
- Weak forces of attraction
- Particles are free to move
- Definite volume but not shape
Describe the particle arrangement of a gas
- Weak forces of attraction
- Don’t have a definite shape or volume
- Constantly move with a random motion
Define the term ‘chemical changes’
When a new product is formed
What is particle model
The simplification of particles depicting them as ‘solid, inelastic spheres’
Compare the difference between a pure substance and a mixture
Pure substance = a single element or compound, not mixed with any other
substance
Mixture = consists of 2 or more compounds not chemically combined
How do pure substances and mixtures vary when melted/boiled
Pure substances have specific melting/ boiling points while mixtures do not
What is simple distillation used for (provide 2 answers)
- The separation of a liquid and a soluble solid
- Separation of a pure liquid from a mixture
Define the word ‘soluble’
Able to be dissolved
Write the steps of fractional distillation
- Heat the solution until pure water evaporates producing a vapour
- Vapour passes through the condenser turning into a pure liquid collected in a beaker
- Once all water is evaporated only the solid solute is left behind
What is filtration used for
The separation of an insoluble solid from a liquid
State the steps of filtration
- A piece of filter paper is placed in a funnel above a beaker
- Mixture of insoluble solid and liquid is poured through
- Small liquid particles will pass through as filtrate
- Solid particles stay behind as residue
What is crystallisation used for
Separation of a soluble solid from a solution
State the steps of crystallisation
- Solution is heated, solvent evaporates leaving a saturated solution
- Leave the saturated solution to cool slowly
- Crystals will begin to grow as solids due to decreasing solubility
- Rinse with cold water to remove impurities and leave to dry
What is chromatography used for
The separation of substances with different solubilities in a solvent
State the steps of Chromatography
- Draw a pencil line on chromatography paper placing spots of the sample on it
- Lower the paper into solvent container leaving the pencil line above the level
- Allow solvent to travel up the paper via capillary action
Why should the line in the chromatography practical be drawn with pen
Ink may run into the chromatogram along with samples
How can you tell the difference between a pure and impure substance based off on a chromatogram
Impure substance = more than 1 spot
Pure substance = 1 spot
What does Rf value stand for
Retention factor
What does calculating the Rf value help to do
Identify unknown substances
What is the equation for Rf values
distance travelled by substance ÷ distance travelled by solvent
Where does the Rf value lie
Between 0 and 1
What is a stationary phase
contained on the paper and does not move through it
What is the mobile phase in chromatography
the solvent that moves through the paper carrying different substances with it
What are the two parts of investigating the composition of inks practical
- Simple distillation
- Chromatography
Investigating Inks: state the steps for simple distillation
- Add small volume of ink to a flask. Connect the flask to the fractionating column and secure it with a stand, boss and clamp.
- Attach condenser to the top of the fractionating column, connect it to a cold water tap and sink, and secure it over a beaker.
- Heat the flask using a Bunsen burner reducing the flame as necessary to achieve gentle simmering.
- Collect a small sample of the distilled
solvent
Investigating Inks: state the steps for chromatography
- draw a pencil line across the chromatography paper, 1-2 cm from the bottom
- use a pipette or capillary tube to add small spots of each ink to the line on the paper
- place the paper into a container with a suitable solvent in the bottom
- allow the solvent to move through the paper
- allow the chromatogram to dry, then measure the distance travelled by each spot and by the solvent
Define the term potable
Safe to drink
What are the free methods of creating potable water
- Filtration
- Sedimentation
- Chlorination
Describe the process of filtration for potable water
clear water passes through filters that have different pore sizes and are made of different materials
Describe the process of sedimentation
large insoluble particles clumped by iron/aluminium sulphate will sink to the bottom of the water
Describe the process of chlorination
chlorine gas is put through water to kill microbes
How can seawater be made potable via distillation
- filter the seawater
- boil it
- water vapour is cooled and condensed
What are 2 negatives of using distillation to curate potable water
- process is expensive as a lot of energy is required
- Wastewater produced is toxic due to high concentration of salts
Why must water used in analyses be pure
any dissolved salts could react with the substances you are analysing, leaving a false result
