Principles Of Chemistry Flashcards
What do ionic compounds form
Giant ionic lattices
They have high melting and boiling points
How do ionic compounds conduct electricity
When molten or in aqueous solutions as they have a delocalised electron so ions are free to move
The positively charged ions are attracted to the negative electrode
What do covalently bonded compounds form
Simple molecular structures - weak intermolecular forces of attractions so they have low melting and boiling points
Describe the structure and properties of diamond
Giant covalent lattice
They have 4 electrons in each carbon atoms which form covalent bonds which are extremely strong
Hard, high melting and boiling points
Describe the structure and properties of graphite
Giant covalent lattice as outer electrons of carbon form 3 covalent bonds
Graphite has layers which have weak intermolecular forces
It is soft as the layers can slide over each other
Delocalised outer electron so can conduct electricity
Describe the structure and properties of C60 fullerene
Separate large molecules with weak intermolecular forces of attraction
It is soft
3 covalent bonds per carbon atoms
No delocalised electron
What increases the strength of the intermolecular forces of attraction
Larger molecules have a greater surface contact and this is why melting and boiling points increase with relative formula mass
Describe how simple distillation works
Heat a flask containing mixture
The liquid will evaporate into a gas which passes through a condenser
Water jacket ensures water in condenser is cool so that gas condenses
Liquid is collected in a beaker
Works well for mixtures with different boiling points
Describe how fractional distillation works
Fractionating collumn is filled with glass beads and is connected to a condenser
Temperature reduces up the collumn
When the gas reaches its boiling point it is condensed
The liquid is collected in a test tube
Liquids that condense further down the tube run back down the collumn
Describe how crystallisation works
Place solution in an evaporating dish
Heat it until saturated solution is produced
If crystals form on glass rod then saturation has occurred
As the solution cools, excess crystals will form
Describe how filtration works
Place filter paper over a funnel into a beaker and pour the solution through
Crystals do not go through the paper, rinse them with distilled water
Allow them to dry
Describe how chromatography works
Draw a line on some chromatography paper using a pencil
Draw dots with different dyes on that line
Place paper in solvent
Solvent runs up the paper, carrying the dyes with it
Different dyes run up the paper at different speeds
How can you measure Rf values
Solvent distance/solvent distance
How to test for diffusion using potassium manganate
Add to a beaker of water, the purple colour will diffuse through the water as it dissolves and reacts with water
How can you observe the diffusion of gases using ammonia solution and HCL
Add cotton soaked in ammonia solution and cotton soaked in HCL on two opposite ends of a tube
White Ring of ammonium chloride forms closer to the HCL due to the ammonia gas particles being lighter and faster than the HCL particles
