Elements, Compounds And Mixtures, Chromatography, Filtration And Crystalisation Flashcards
What is an element?
A substance made up of only one type of atom
What is a compound?
A substance made up of more than one type of atom ( element) chemically combined.
What is a mixture?
Something made up of more than one substance not chemically join eg- air, sea water. Can be physically separated
What is crystallisation?
- separates a soluble solid from a solution
Steps for crytallisation
- Place the solution in an evaporating basin
- heat to evaporate some of the water
- Check that crystals will form on a cold glass rod
- leave to cool and form crystals
- filter to collect the crystals
- Wash with a little cold distilled water
- Dab crystals with a dry paper towel
What is filtration?
Separates an insoluble solid form a liquid
What are the three diffusion experiments?
- potassium manganate ( VII) and water
-ammonia and hydrogen chloride - bromine gas and air
Experiment for potassium manganate and water
- potassium manganate is bright purple
- take beaker of water
- place potassium manganate at the bottom
- colour slowly spread out to fill the beaker
Why does the purple colour of potassium magnate spread out throughout the beaker?
- particles of potassium manganate are diffusing out among the particles of water
- it is the random motion of particles in a liquid that causes the purple colour to eventually be evenly spread out throughout the water
In the potassium manganate ( VII) experiment, what would happen if you added more water? What would this be called?
- potassium manganate ( VII) would spread eve further apart and the solution would be less purple- called dilution
Ammonia and hydrogen chloride summary
- aqueous ammonia gives off ammonia gas
- hydrogen chloride gives off hydrogen chloride gas
- white ring of ammonium chloride will form in glass tube
Apparatus for ammonia and hydrogen chloride experiment-
• Glass tube with rubber bungs
• Cotton wool soaked in ammonia (NH₃)
• Cotton wool soaked in hydrochloric acid (HCl)
Method and observations of experiment- ammonia and hydrogen chloride
Method:
1. Place NH₃-soaked cotton wool at one end of the tube and HCl-soaked cotton wool at the other.
2. Seal the tube and observe where the white ring of ammonium chloride (NH₄Cl) forms.
Observations:
• The white ring forms closer to the HCl side because:
• NH₃ (Mr = 17) is lighter and diffuses faster.
• HCl (Mr = 36.5) is heavier and diffuses slower.
Method, observations and conclusions for bromine gas and air-
Method:
1. Setup: Place the bromine-filled gas jar below the air-filled gas jar, separated by a glass plate.
2. Remove the Divider: Carefully lift the glass plate between the jars.
3. Observe Diffusion: Over time, the reddish-brown bromine gas spreads upward into the air-filled jar.
Observations:
• Bromine gas slowly spreads until both jars have a uniform brown color.
• No stirring or external force is needed—diffusion happens naturally.
Conclusion:
• Gas particles move randomly and spread from high to low concentration.
• Diffusion in gases is slower than in liquids but occurs without external mixing.
Filtration method
- used when a product of a reaction is an insoluble soli- use to separate it out from the liquid reaction mixture
- used for purification. Solid impurities can be separated out from a reaction mixture using filtration.
- filter paper into funnel, pour mixture through it. Liquid part of the mixture runs through the part leaving behind a solid residue .
What do you use filtration and crystallisation for?
-To separate a rock salt ( mixture of salt and sand)
Method of filtration and crystallisation-
- grind the rock salt with a pestle and mortar
- dissolve in a beaker of water and stir
- FILTRATION- filter through filter paper in a funnel
- CRYSTALLISE METHOD- evaporate in an evaporating dish
- the sand ( insoluble salt) doesn’t dissolve and it is insoluble and stays in big grains. Won’t fit through tiny holes in the filter paper do it collects the filter paper
- salt ( soluble) is dissolved in Solution and when’s the water’s evaporates the salt forms crystals int he evaporating dish ,
