1. Aim to look at a ‘varity of reactions…’
Chemical Reactions
Aim to look at a ‘varity of reactions…’
Double replacement reactions
(Precipitate reaction)
Synthesis reactions
Decomposition reactions
Single replacement reactions

2. Word equation Chemical equation
Chemical Reactions can be written as:
Word equation
Hydrogen + Oxygen water
Reactant (s) Product (s)
Chemical equation
2H2 + O H2O
Equations must be balanced ie have the same # and type of atoms on either side of →

3. Equations must be balanced ie have the same # and type of atoms on either side of →

4. 1) Decomposition reactions
Is when a compound ‘breaks down’ into elements or simpler compounds
AB A + B
Aim: Investigate the decomposition of hydrogen peroxide catalyzed by Iodine (Elephants toothpaste)
Method: To 2 ml of concentrated 30% Hydrogen peroxide add 1 ml of KI (acts as a catalyst – initiates / starts the decomposition reaction)
Check for O2 gas with a flame test
Word Equation:
Formulae Equation:
Observations:
Hydrogen peroxide → Water + Oxygen gas
2H2O2 → 2H2O + 02

5. 2Mg + O2 2MgO 2Fe + 3O2 2Fe2O3 2) Synthesis reactions Mg2+ O2-
Is when an element or compounds build or make new simpler compounds
A + B AB
2Mg + O MgO
Heat
Mg O2-
2Fe + 3O Fe2O3
Heat
Fe O2-

6. Aim: Does steel wool weigh more or less after burning?
Synthesis reactions
Theory: Iron in steel wool reacts with oxygen from the air to form iron oxides. The oxygen from the air has mass and adds to the mass of the iron. The result is material that is heavier than the iron alone.
Word Equation:
Chemical Equation:
Observations:
Assumptions & conclusions

7. Procedure:
Pull apart steel wool. Fluff as big as you can without it hanging off of the scale. This is so oxygen can get into all parts of the wool
Make observations on the wool.
Accurately measure the mass of the fluffed steel wool.
While the wool is still on the scale light it with a candle, holding the wool with tongs.
Write observations during and after the wool is burning.
Make observations on the burnt wool.
Record the mass of the wool after it has burned.

8. Observations of Steel wool before during and after burning
Before the Burn
Gray material
Strong metallic smell
Small wires of metal interwoven
Flexible, strong material
Mass = 0.243g
During the Burn
dark smoke
Some sparks
The Reaction seems to follow each strand of the wool.
After the Burn
There is a new color ~ it is more ‘bluer’ in color
Some small parts are the same as before being burnt.
It looks a similar same shape and size as before.
Mass= 0.262g

9. Acid + Metal = Metal salt + Hydrogen gas
3) Single replacement reactions
One elements or group is replaced by another element or group of elements.
A BC AB C
An example is an acid + metal reaction
Aim: Investigate adding Mg to HCl acid
Method: Add 1 strip Mg to 2ml HCl and collect H2 gas in a small balloon then pop (explode) with a candle flame.
Word Equation:
Chemical Equation:
Observations:
Acid + Metal = Metal salt + Hydrogen gas
2HCl + Mg → MgCl2 + H2

10. Chemical state notation
(aq)
(s)
(aq)
(g)
(aq) means exists in an aqueous state
(g) means exists in a gaseous state
(s) means exists in a solid state
(l) means exists in a liquid state

11. (aq) means exists in an aqueous state
NaCl (s)
NaCl (aq)

12. 4) Double replacement reactions (Precipitate reaction)
A precipitate is formed whenever two solutions that chemically react can provide a combination of ions, which are insoluble.
If the substance lacks the ability to dissolve in water (form aqueous ions) the molecules form a precipitate.

13. 4) Double replacement (precipitate) reactions
A double replacement happens when two lots of ions are swapped over.
AB CD AD CB
Precipitate reactions is when a solid forms in a solution
CaCl2
(calcium chloride)
Na2CO3
(sodium carbonate)
Non-
Metal
Non-
Metal
Metal
Metal
CaCO3
(calcium carbonate)
NaCl
(sodium chloride)
Non-
Metal
Non-
Metal
Metal
Metal

14. Aim: to Observe and analyse Five Precipitate reactions
Equations- for the reaction that has occurred write out;
1. a word equation
2. a balanced chemical equation
Observations:
Describe what you started with
Describe what you are left with
1) Method: Add 1ml of Na2CO3 (sodium carbonate) to 1 ml of CaCl2 (calcium chloride)
2) Method: Add 1ml of FeSO4 (iron (ii) sulfate) to 1ml of NaOH (sodium hydroxide)
3) Method: Add 1ml of FeCl3(iron (iii) chloride) to 1ml of NaOH (sodium hydroxide)
4) Method: Add 1ml of of KI (potassium iodine) to 1ml of Pb(NO3)2 (lead nitrate)
5) Method: Add 1ml of CuSO4 to 1ml of NaOH (sodium hydroxide )

15. Aim: to Observe and analyse Five Precipitate reactions
1) Method: Add 1ml of Na2CO3 (sodium carbonate) to 1 ml of CaCl2 (calcium chloride)
Word equation:
Chemical equation:
Na2CO3 + CaCl2 =
Observations:
2) Method: Add 1ml of FeSO4 (iron (ii) sulfate) to 1ml of NaOH (sodium hydroxide)
Word equation:
Chemical equation:
FeSO4 + NaOH =
Observations:
3) Method: Add 1ml of FeCl3(iron (iii) chloride) to 1ml of NaOH (sodium hydroxide)
Word equation:
Chemical equation:
FeCl3 + NaOH =
Observations:
4) Method: Add 1ml of of KI (potassium iodine) to 1ml of Pb(NO3)2 (lead nitrate)
Word equation:
Chemical equation:
KI + Pb(NO3)2 =
Observations:
5) Method: Add 1ml of CuSO4 to 1ml of NaOH (sodium hydroxide)
Word equation:
Chemical equation:
CuSO4 + NaOH =
Observations: