Chemical change- Chemistry

  • Created by: mia ramo
  • Created on: 11-11-19 17:03

Chemical change set.

A base neutralises an acid. Some examples of a soluble and insoluble base are Soluble base (alkali) e.g. Sodium hydroxid Insoluble base e.g. Zinc oxide

What is the neutralisation equation?  H + + OH -  H 2 O

Strong acid – fully ionised in solution e.g. nitric acid

Weak acid – partially ionised in solution e.g. ethanoic acid


pH 1 – Red – Strong acid

pH 6 – Yellow – Weak acid

pH 7 – green – neutral

pH 8 – blue - weak alkali

pH 14 – purple – strong alkali

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Chemical change sett.

As the pH concentration decreases by one unit…….. The hydrogen ion concentration increases by a factor of 10

You can make copper sulfate crystals using an insoluble base and an acid:

Warm the acid

 Add copper oxide to excess

Filter the mixture

Warm the copper sulfate solution over a water bath til crystals first appear

Pour into a petri dish and leave to crystallise

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Cchemical change set.

Electrolysis – Using electricity to separate compounds

Cathode – Negative electrode

Anode – Positive electrode

Electrolyte - Compound is being separated into elements

In electrolysis, what always happens to the (movement and electrons):

Metal ions – Move to the negative electrode and gains electrons

Non-metal ions – Move to the positive electrode and lose electrons

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chemical change set

Describe the process of extracting aluminium from aluminium oxide using electrolysis (think about the electrodes, electrolyte, half equations)

Dissolve aluminium oxide into cryolite

 Al 3+ + 3e -  Al

 2O 2- - 4e -  O 2

 Carbon electrodes wear away as the oxygen reacts with them to form carbon dioxide

the rules for the electrolysis of aqueous compounds are 

At the negative electrode – least reactive out of metal or hydrogen

 At the positive electrode – group 7 given out if not oxygen from hydroxide.

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Oxidation and reduction

Oxidation is gain of oxygen

Reduction is loss of oxygen

OIL RIG Oxidation is loss of electrons

Reduction is gain of electrons

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reactivity series









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chemical change set 1

one metal may be more reactive than another bacause It has a greater tendency to form positive ions.

Displacement reaction

More reactive metal replaces less reactive metal in compound

Magnesium + iron nitrate  magnesium nitrate + iron

How can metals be extracted from their


Unreactive metals e.g. gold found as the metal itself 

If below carbon in reactivity series – use carbon to displacethem from the oxide

If above carbon – use electrolysis

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Acids and Alkalines

Acids – H + ions

Alkalis – OH - ions


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Soluble Salts

soluble salts

Acid + metal  salt + hydrogen

Acid + alkali  salt + water

Acid + metal oxide  salt + water

Acid + carbonate  salt + water + carbon dioxide

What type of salt does each acid make?

Hydrochloric acid (HCl) - chloride

Sulfuric acid (H 2 SO 4 ) - sulfate

Nitric acid (HNO 3 ) - nitrate

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chemical change sett 1

metal reacting with an acid is a redox reaction because the metal is oxidised (loses electrons) to form a positive ions The hydrogen ion is reduced (gains electrons) to a hydrogen atom

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ionic equations and half equations

Magnesium + hydrochloric acid  magnesium chloride

+ hydrogen

Mg + 2H +  Mg 2+ + H 2

Mg – 2e -  Mg 2+

2H + + 2e -  H 2

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chemical change

the end

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