Chemistry C2

Chemistry C2 Revision Cards For AQA GCSE

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  • Created by: bobby
  • Created on: 31-12-09 17:27

Atoms

Mass Charge Location

  • Proton 1 +1 Nucleus
  • Neutron 1 0 Nucleus
  • Electron 1/2000 -1 Orbiting Nucleus
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Atoms

The Mass Number = The Top Number

16

O

8

The Atomic Number = The Bottom Number

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Isotopes





Isotopes are different atomic forms of the same elements, which have the SAME number of PROTONS

(but a DIFFERENT number of NEUTRONS)

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Ions




Ions are electrically charged particles formed when atoms lose or gain electrons.

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Ions


Metal atoms form positive ions,

while

non-metal atoms form negative ions.

METAL ATOMS LOSE ELECTRONS.

NON METAL ATOMS GAIN ELECTRONS.

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Ionic compounds




Ionic compounds have high melting and boiling points.

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Bonding

Sharing Elections = Covalent Bonding


Swapping Electrons = Ionic Bonding

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Covalent Bonding



A Covalent bond is a strong bond between two non-metal atoms.


It consists of a SHARED pair of electrons

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Calculations




Ar = Relative Atomic Mass (The Mass Number)

Mr = Relative Formula Mass (The sum of all the Ar's of a compound)



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Calculations

Ar x No. of atoms (of the element)

Percentage of an = -------------------------------------------------------------- x100

element in a compound Mr (of the whole compound)

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Calculations

Empirical Formula - Phosphorous Oxygen

1. Write the mass given 62g 48g

or percentage.

2. Mass ÷ Ar 62÷31=2 48÷16=3

3. Divide both numbers by

the smallest number 2÷2=1 3÷2=1.5

4. The ratio becomes the

solution. =P₂0

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Calculating Mass in Reactions

60g of Mg reacts to give how much MgO?

1. Write the balanced equation 2Mg + 0₂ --> 2MgO

2. Work out Ar & Mr 48 80

48g of Mg reacts to make 80g of MgO

3. Divide amount (48) 1g of Mg reacts to make 1.67g of MgO

4. Multiply by amount you want (60) 60g of Mg reacts to make 100.2g of MgO

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Rate of Reaction

Rate of reaction depends upon:

Concentration

Size of particles

Catalyst

Temperature

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Speed of a reaction

There are 3 ways to measure the speed of a reaction:

  • Precipitation
  • Change in mass
  • Volume of gas given off
  • Rate of reaction = amount of product formed ÷ Time
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Exo and Endo

EXOTHERMIC REACTIONS give out heat

ENDOTHERMIC REACTIONS take heat in

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Exo

Some examples of EXOTHERMIC REACTIONS are:

  • Burning
  • Neutralisation reactions between acids and alkalis
  • The reaction between water and calcium oxide
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Endo

Some examples of ENDOTHERMIC REACTIONS are:

  • Electrolysis
  • The reaction between ethanoic acid and sodium carbonate
  • the thermal decomposition of calcium carbonate in a blast furnace
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Reversible Reaction


A reversible reaction is where the products of a reaction can themselves react to reproduce the original reactants.

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The Haber Process

Hydrogen and Nitrogen are, at high pressure (200 Atmospheres), passed over an Iron catalyst at 450°C. Some of the Hydrogen and Nitrogen combine to form Ammonia (2NH₃), this ammonia is collected and the remaining Hydrogen and Nitrogen are re-used.

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Haber Process


The forward reaction which makes ammonia is EXOTHERMIC.


Therefore the Yield is much better at Lower temperatures.

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Haber Process

Haber Process = Low Temperature and High Pressure

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Ammonia




Ammonia is used to make fertilisers, explosives, dyes, househoold cleaners and nylon.

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Electrolysis of Copper

The electrical supply pulls electrons off at the anode and the copper goes into the solution as Cu²⁺ ions where they are offered electrons at the cathode, pure copper is then made at the cathode whilst all the impurities drop to the bottom.

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Electrolysis

+ve Ions = Cations

-ve Ions = Anions

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Percentage Yield

Actual Yield

Percentage Yield = -------------------------------------------- x100

Predicted Yield

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