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

Word equation Chemical equation Chemical Reactions can be written as: Word equation Hydrogen + Oxygen water Reactant (s) Product (s) Chemical equation 2H2 + O2 2 H2O Equations must be balanced ie have the same # and type of atoms on either side of →

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

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

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 + O2 2MgO Heat Mg2+ O2- 2Fe + 3O2 2Fe2O3 Heat Fe3+ O2-

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

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.

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

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

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

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

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.

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

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 )

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: