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The Haber Process Nitrogen from the air Low temperatures
Relative formula Mass
Making Ammonia Hydrogen from natural gases will increase the
Add the mass of each atom in the
yield of exothermic
exothermic reactions. formula together
endothermic High temperatures e.g. CaCO3
will decrease the
Un-reacted gases recycled
yield of exothermic
4 molecules 2 molecules
reactions. 40 + 12 + 16 + 16 + 16 = 100
If temperature are We compare the mass of
If temperatures are
Conditions: Moles
low a reaction
a reaction any atom to Carbon 12
·450oC will
be too slow.
too slow. 1 mole of any substance
mpr ·200 atmospheres
contains the same number of
A Co
·Iron Catalyst Mass of element
Increasing pressure particles. (6.02x1023)
will increase the yield
Total mass of compound x 100
Separate out Ammonia using it's on the side with less Relative atomic mass or formula = Percentage Mass
boiling point (it condenses) molecules. mass in grams is equal to one mole.
BUT e.g. 12g of carbon is one mole of e.g. % mass of carbon (12) in
High pressures are ethane C2H6 (30)
Used for Fertilisers, expensive.
= 24)
Explosives & Dyes on (12 + 12
All the carb 24 / 30 x 100 = 80%
Make sure you can Too removed a solid (s) from a
explain this in reverse!
reaction you FILTER it out !
Exothermic reactions give out heat to
the surroundings(get hotter) e.g. Respiration & Combustion If you reaction gives you a
When a reaction forms a dissolved product (aq) instead,
Endothermic reactions take in heat SOILD(s) its called a you EVAPOURATE it out !
from the surroundings (get colder) e.g. Photosynthesis PRECIPITATE
We can measure the rate of a
e.g. Sulfuric Acid + Magnesium -> Magnesium sulfate+ Hydrogen reaction by looking at how fast solid
n her Collision Theory
e a ctio t e.g. Nitric Acid + Copper Oxide -> Copper nitrate + Water reactants are used up, how quickly
R nd e ot h
e r s ible mic
ther rmic eact
Acid Salt
The rate of a reaction is speed gas is produced or how quickly light
is blocked (the disappearing cross)
e v e nd o
R y will be l be exot and bacsk
h e w ard r up by increasing the:
wa wil orward al rate For this: ·Temperature When we increase the concentration/surface
One mf equ Anything that's not a Hydrochloric
ed s
yst e
at Chloride ·Surface area area we increase the frequency of particles
clos o metal on its own is a base Acid ·Concentration
In a colliding and reacting. Speeding up the
Acid + Metal Salt + Hydrogen ·Or by adding a CATALYSIS reaction.
Sulfuric Acid Sulfate Catalysts speed up reactions without being used up
Acid + Base Salt + Water When we increase the temperature the
Increase in pressure is the
Nitric Acid Nitrate same as increase in particles move faster, they are more likely to
Acids & Bases (Alkalis) concentration
collide and do so with sufficient energy to
Acids ­ H+ An increase of 10oC
react. Speeding up the reaction.
Alkalis ­ OH- doubles the rate of a
For a reaction to take place we have to have
Bases NEUTRALISE acids the minimum amount of energy needed
Alkalis are soluble bases
pH Scale
Find the pH using Universal Indicator The ACTIVATION ENERGY…read more

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Molecular Formula & Balanced Equations Percentage Yield
Empirical Formula This is used to compare our actual yield with our
theoretical yield.
Molecular Formula : The actual number of atoms of
each element in an individual molecule Amount of product actually produced
Empirical Formula : The simplest whole number ratio Maximum possible yield (Theoretical yield) x 100
of the elements in the molecule
e.g. 200
Calculating the Empirical Formula 275 x 100 = 72.73 %
A balanced equation has the same number of
1) Use the same table and method given for calculating atoms for each element on both sides Its rare to get 100% yield
reacting masses but remove the ratio row. This is because some products can be left in
The question will either provide the grams of each We can use this to find the ratio of moles that are apparatus or separating products from reactants is
element or the percentage. Assume percentages are needed to react with one another difficult.
the same figure in grams. e.g. 1 CH4 molecule reacts with 2 O2 molecules Sometimes it's not everything reacts to begin with.
e.g. 12% = 12g 1:2 ratio
Question: A substance contains When doing an experiment if This is useful if we want Atom Economy
24% carbon and 64% hydrogen. we know the grams used and to calculate how much This calculates the amount of starting material
the Molecular/Formula Mass g product we would get that ends up as useful products
Calculate the its empirical The aim is always for the highest atom economy possible
we can calculate the moles from a specific amount
e.g. In 24 g of carbon which
Grams of reactant
Chemical Carbon Hydrogen has an Mr of 12 there would THEORETICAL YIELD Formula mass of useful products
be 2 moles of carbon. Formula mass of all products x 100
Grams 24 64
24/12 = 2
n Mr
Mr 12 16 Moles Molecular/ e.g. 44
Formula Mass (44 + 18 +18) x 100 = 55 %
Moles 2 4
Calculating Theoretical yield High atom economy conserves resources, reduces
2) To get the simplest ratio Question: How much CO2 would be produced by burning 100g of pollution and maximises profits
divide all moles by the Methane (CH4) ?
smallest calculated value
2/2 = 4/2 = 1) Put in the things you
Chemical CH4 CO2 4) Now you have the Mr
and the moles of CO2
1 : 2 already know. You were Ratio 1 1 you can use the triangle All figures in
This gives you the number of given the grams of to calculate the grams example calculations
each element present and the methane in the Grams 100 ? that will be produced. refer to the burning
empirical formula question. And can
calculate the Mr using
of methane in oxygen
Mr 16 44
C H2 the periodic table. 44 x 6..25 = 275 as shown in the
If you were told the compound had a mass of 28 you
Moles 6.25 6.25 balanced equation
Answer: 100g of
could calculate the molecular formula 2) Use the triangle to
The Mr of CH2 is 14 3) Use the ratio from balanced equation to provide the methane would make
28 /14 = 2 calculate the moles or
Therefore the molecular formula must be double the moles of CO2 275 g of CO2
methane used.
empirical one C2H4 1:1 6.25 : 6.25…read more



hi my name is carina Wilshaw l need help to revision for my exam on Wednesday

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