3.1 Introduction Flashcards
Good observations when describing substances
- Solid, Liquid, Gas?
- Coloured or Colourless?
- Crystalline or Powdered (Solid)?
- Clear or Cloudy (Liquid)?
Good observations when describing change
- Fizzing/Effervescence?
- Solid appeared or disappeared?
- Colour change?
- Sounds or smells?
Physical change
- No new substances
- Easy to reverse
- Release small amounts of energy
Example of physical change
Ice melting, can be frozen again
Chemical change
- Creates new substance
- Difficult to reverse
- Release large amounts of energy
Example of chemical change
Burning wood, can’t reverse, very hot, turns into soot
Chemical test for water
Anhydrous copper sulphate turns white to blue if water is present
Physical tests for water
Melting point = 0C
Boiling point = 100C
Purer water matches properties closer
Element
One type of atom
Properties of a metal
- High melting/boiling point
- Electrical conductors
- Malleable
- Shiny
Properties of a non-metal
- Low melting/boiling point
- Electrical insulators
- Brittle
- Dull
Which are the diatomic elements?
Found in an L shape starting at nitrogen to astatine
Compound
More than one type of atom, chemically bonded
How to make a compound
Compounds are often formed by heat, e.g. Zinc + Sulphur —> Zinc Sulphide
Types of compounds
Metallic, Ionic (metal + non-metal), Covalent (non-metals)
Ammonium Chloride Tube Practicle
- Making the compound ‘Ammonium Chloride’ is used to show diffusion
- Two gases diffuse from 2 ends of sealed tube (Ammonium + Hydrogen Chloride)
- Hydrogen Chloride doesn’t diffuse as far, meaning it’s molecules are heavier
- Heating up tube increases rate of reaction as they have more energy and collide more often
Solute
The substance going to be dissolved
Solvent
The liquid which is going to do the dissolving
Solution
The mixture of the solute dissolved in the solvent
Saturated
A solution in which no more solute can be dissolved in
Suspension
A solid floating in the liquid as it cannot dissolve
Soluble
A substance that can be dissolved
Insoluble
A substance that cannot be dissolved
Unit for solubility
g per 100g of solvent
What does the line mean in a solubility curve?
Line = Saturated
Shows the maximum mass of solid which can be dissolved at each temperature
What does the below the line mean in a solubility curve?
Below = Soluble
Shows less than maximum mass of a solid so it will all dissolve at a specific temperature
What does the above the line mean in a solubility curve?
Above = Insoluble
More than the maximum mass of solid that can be dissolved. The mass that dissolves can be found by reading off the line
What is 36g of sodium chloride per 100g in 50g?
18g per 50g
