C3: Chemical reactions Flashcards
How are the formulae of metal elements written?
In empirical formulae.
What are Group 7 elements?
They are diatomic molecules.
Written as: Br2
What is conservation of mass?
Mass is never gained or lost in a chemical reaction. (In a closed system)
What’s an ionic equation?
Symbol equation but showing ions and their charge.
What’s an half equation?
Show the change in charge of an element in a reaction.
How can ionic equations be reduced?
Spectator ions are removed. (Same ions on each side)
What happens when 2 elements combine? (Name)
The ending is IDE.
E.g. magnesium oxide
What happens when 3+ elements combine & one of them is oxygen?
The ending is usually ATE.
E.g. Copper sulphate
What’s a mole?
Moles are measurements of chemical amounts.
What’s avogadro’s constant.
Number of atoms/molecules/ions in 1 mole of a substance.
6.02 x 10^23
What’s equation for moles?
moles = mass/Mr
Which metals are less reactive than hydrogen?
Copper, Silver & Gold.
What’s an acid?
Contain hydrogen and release hydrogen ions when dissolved ins water.
What’re bases?
- Opposite to acids
- Contain elements that react with acids to make water
What’s an alkali?
- Are bases
- Contain OH ions
Word equations for neutralisation?
Acid + Alkali –> Salt + Water
Acid + Carbonate reaction
Acid + Carbonate —> Salt + water + carbon dioxide
Metal + Acid reactions?
Acid + Metal —> Salt + Hydrogen
What does a catalyst do?
- Lowers activation energy
So: - Bonds break more easily
- Reaction is faster
What releases energy? EXO
Forming bonds
What takes in energy? ENDO
Breaking bonds
How to measure pH levels?
- pH Sale
- pH proves
- Universal Indicator
What goes to Anode and what goes to Cathode?
Anode (Positive): Negative ions
Cathode (Negative): Positive ions
What happens at the anode (electrons)?
Negative ions lose electrons to become atoms/molecules.
What happens at the cathode (electrons)?
Positive ions gain electrons to become atoms/molecules.
Rules for anode:
If ions are halides, the halogen is produced
If they aren’t halides, oxygen is produced.
Rules for cathode:
If ions are more reactive than hydrogen, then hydrogen is produced.
If ions are less reactive than hydrogen, then the metal is produced.
