OCR Gateway Additional Science

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OCR Gateway Additional Science
C3 Chemical Economics
W Richards The Weald School
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Fundamental Concepts
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Elements
If a solid, liquid or gas is made up of only one
type of atom we say it is an element. For
example, consider a tripod made up of iron
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Compounds
Compounds are formed when two or more elements
are chemically combined. Some examples
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Chemical formulae
The chemical formulae of a molecule or compound
is simply a way of showing the ratio of atoms in
it. For example
sodium chloride (NaCl)
potassium iodide (KI)
potassium nitrate (KNO3)
K
N
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Some simple compounds
Carbon dioxide, CO2
Water, H2O
Ethyne, C2H2
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Chemical formulae

• Try drawing these
• Water H2O
• Carbon dioxide CO2
• Calcium sulphate CaSO4
• Magnesium hydroxide Mg(OH)2

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Naming compounds
Rule 1 If two identical elements combine then
the name doesnt change
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Naming compounds
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Naming compounds

1. Potassium hydrogen oxygen
2. Lithium hydrogen oxygen
3. Calcium hydrogen oxygen
4. Mg(OH)2

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Naming compounds
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Balancing equations
Consider the following reaction


This equation doesnt balance there are 2
hydrogen atoms on the left hand side (the
reactants and 3 on the right hand side (the
products)
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Balancing equations
We need to balance the equation


Now the equation is balanced, and we can write it
as
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Some examples
2 2 2 3
2 2 2 2 3
2 2 2 2 2 4
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Simple formulae to learn
Covalent formulae
Ionic formulae
H2O CO2 NH3 H2 O2 N2 SO2
Water Carbon dioxide Ammonia Hydrogen Oxygen Nitro
gen Sulphur dioxide
NaCl CaCl2 MgO HCl H2SO4 HNO3 NaOH Ca(OH)2 CaCO3 A
l2O3 Fe2O3
Sodium chloride Calcium chloride Magnesium
oxide Hydrochloric acid Sulphuric acid Nitric
acid Sodium hydroxide Calcium hydroxide Calcium
carbonate Aluminium oxide Iron oxide
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Bonding revision
Hi. My names Johnny Chlorine. Im in Group 7,
so I have 7 electrons in my outer shell







Id quite like to have a full outer shell. To do
this I need to GAIN an electron. Who can help me?
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Bonding
Here comes my friend, Sophie Sodium
Hey Johnny. Im in Group 1 so I have one
electron in my outer shell. Im quite happy to
get rid of it. Do you want it?
Okay
Now weve both got full outer shells and weve
both gained a charge. Were both called IONS and
weve formed an IONIC bond.
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Covalent Bonding
Here comes one of my friends, Harry Hydrogen
Hey Johnny. Ive only got one electron but its
really close to my nucleus so I dont want to
lose it. Fancy sharing?
Now were both really stable. Weve formed a
covalent bond, a bond that often forms between
non-metals.
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C3a-c Rates of Reaction
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Rates of Reaction introduction
Which of these reactions would be classed as a
fast rate of reaction and which would be slow?
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Measuring the Rate of Reaction
Two common methods
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Rate of reaction graph v1
Time taken for reaction to complete
Temperature/ concentration
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Rate of reaction graph v2
Amount of product formed/ amount of reactant used
up
Time
Common units are g/s, g/min, cm3/s or cm3/min
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Rate of reaction graph
Q. What if less reactants were used?
Amount of product formed/ reactant used up
Time
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Rates of Reaction
Oh no! Here comes another one and its got more
energy
No effect! It didnt have enough energy!
Here comes another one. Look at how slow its
going
Hi. Im Mike Marble. Im about to have some
acid poured onto me. Lets see what happens
It missed!
Here comes an acid particle
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Rates of Reaction
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Catalysts

• Task
• Research and find out about two uses of catalysts
  in industry, including
• Why they are used
• The disadvantages of each catalyst

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Catalyst Summary
Catalysts are used to ____ __ a reaction to
increase the rate at which a product is made or
to make a process ________. They are not
normally ___ __ in a reaction and they are
reaction-specific (i.e. different reactions need
_________ catalysts).
Words different, speed up, used up, cheaper
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Rate of reaction graph - catalysts
Amount of product formed/ reactant used up
Time
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An example question
Consider the following graph showing the mass
lost during a reaction between marble chips of
different surface areas and acid

1. How much mass had been lost for the large chips
   in the first 200s?
2. How much extra mass had been lost by the small
   chips (compared to large) after 400s?
3. What mass of large chips would you predict to
   have left after 500s?

0.8g
0.2g
94.2g
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Dust Explosions
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C3d Reacting Masses
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Atomic mass
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Relative formula mass, Mr
The relative formula mass of a compound is the
relative atomic masses of all the elements in the
compound added together.
E.g. water H2O
Therefore Mr for water 16 (2x1) 18
Work out Mr for the following compounds

1. HCl
2. NaOH
3. MgCl2
4. H2SO4
5. K2CO3

H1, Cl35 so Mr 36 Na23, O16, H1 so Mr
40 Mg24, Cl35 so Mr 24(2x35) 94 H1, S32,
O16 so Mr (2x1)32(4x16) 98 K39, C12,
O16 so Mr (2x39)12(3x16) 138
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Conservation of Mass
Heres a classic experiment where magnesium is
burned in a crucible
Mass is always conserved in any reaction, so
where did this extra mass come from?
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Calculating the mass of a product
E.g. what mass of magnesium oxide is produced
when 60g of magnesium is burned in air?
Step 2 WORK OUT the relative formula masses
(Mr) 2Mg 2 x 24 48 2MgO 2 x
(2416) 80

• Step 3 LEARN and APPLY the following 3 points
• 48g of Mg makes 80g of MgO
• 1g of Mg makes 80/48 1.66g of MgO
• 60g of Mg makes 1.66 x 60 100g of MgO

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• Work out Mr 2H2O 2 x ((2x1)16) 36
  2H2 2x2 4
• 36g of water produces 4g of hydrogen
• So 1g of water produces 4/36 0.11g of hydrogen
• 6g of water will produce (4/36) x 6 0.66g of
  hydrogen

Mr 2Ca 2x40 80
2CaO 2 x (4016) 112 80g produces 112g so
10g produces (112/80) x 10 14g of CaO
Mr 2Al2O3 2x((2x27)(3x16)) 204 4Al
4x27 108 204g produces 108g so 100g produces
(108/204) x 100 52.9g of Al2O3
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Another method
Try using this equation
Mass of product IN GRAMMES
4
6g
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So mass of product (4/36) x 6g 0.66g of
hydrogen
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C3e Percentage Yield and Atom Economy
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Problems with calculating masses
Calculating the amount of a product may not
always give you a reliable answer...

1. The reaction may not have completely _______
2. The reaction may have been _______
3. Some of the product may have been ____
4. Some of the reactants may have produced other
   _______

The amount of product that is made is called the
____. This number can be compared to the
maximum theoretical amount as a percentage,
called the percentage yield.
Words lost, yield, finished, reversible,
products
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Percentage Yield
Theoretical yield the amount of product that
should be made as calculated from the masses of
atoms Actual yield what was actually produced
in a reaction
Example question
The theoretical yield is 136g (using Cl 35.5)
so the yield is 75
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Percentage yield

• Some example questions
• The predicted yield of an experiment to make salt
  was 10g. If 7g was made what is the percentage
  yield?
• Dave is trying to make water. If he predicts to
  make 15g but only makes 2g what is the percentage
  yield?
• Sarah performs an experiment and has a percentage
  yield of 33. If she made 50g what was she
  predicted to make?

70
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150g
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Atom Economy
Calculate the atom economies of the following
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99
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Chemical Economics
Hi. Were industrial scientists and we want to
make lots of chemicals and sell them to make
money. What problems would we face?

• Possible problems with making chemicals
• Reactions often produce chemicals that arent
  commercially useful or that cant be sold
• To reduce the costs we want to make sure that no
  reactants are wasted

Therefore we need reactions and processes that
give us a high percentage yield and high atom
economy.
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C3f Energy
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Endothermic and exothermic reactions
28/04/2014
Step 1 Energy must be SUPPLIED to break bonds
Step 2 Energy is RELEASED when new bonds are
made
A reaction is EXOTHERMIC if more energy is
RELEASED then SUPPLIED. If more energy is
SUPPLIED then is RELEASED then the reaction is
ENDOTHERMIC
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Common examples of these reactions
Are these reactions exothermic or endothermic?
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Example reactions
28/04/2014
Reaction Temp. after mixing/OC Exothermic or endothermic?
Sodium hydroxide dilute hydrochloric acid
Sodium hydrogencarbonate citric acid
Copper sulphate magnesium powder
Sulphuric acid magnesium ribbon
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Energy from fuels
28/04/2014
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Experimental values
Step 1 Calculate the energy gained by the
water Energy gained by water mass of water x
4.18 J/gC0 x change in temperature Step 2
Divide this value by the mass of the alcohol used
to find out the energy gained by the water per
gram of alcohol Energy gained per gram (answer
to Step 1) / mass of alcohol burned
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An example calculation
While doing this experiment, Dave got the
following results for methanol
Mass of water Start temp End temp Temp diff Start mass End mass Mass diff
100g 16 51 35 159.67 158.22 1.45
Step 1 100g x 4.18 J/gC0 x 35 14630 J Step
2 14630 / 1.45 10090 J/g Therefore energy
given out by the alcohol 10090J/g
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Other ways of finding an energy change
The amount of energy produced by a reaction can
also be found by measuring an energy change
By mixing the reactants in an insulated container
the energy change can be measured by observing
the change in temperature.
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C3g Batch or Continuous?
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Batch and Continuous processes
In summary
Process Batch Continuous
What it means Reactants are thrown in, the reaction happens and the batch is removed The reactants are continually fed in and the products are continually removed (e.g. the Haber Process)
Advantages Makes a wide variety of products on demand Operate all the time and automatically, makes a large amount of product
Disadvantages More labour intensive Can only make one product
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Researching new drugs An introduction to
thalidomide
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Developing new drugs
Before a new drug can be approved it has to go
through a strict testing process. Consider the
example of thalidomide
Date Event
Mid 1950s
Late 1950s
Early 1960s
Mid 1960s
Animal testing using thalidomide was undertaken.
Tests showed that it was safe but the tests were
inadequate no tests were done on pregnant
animals
Thalidomide prescribed to pregnant mothers to
help sleep and morning sickness problems
Babies are born with birth defects and the drug
was banned worldwide. Around 12,000 deformed
Thalidomide babies born, 4,000 die in first year.
Tests show that Thalidomide can help leprosy
sufferers and it is still used today for this
purpose.
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Developing new medicines
An expensive process
Step 1 - research
Step 2 - development
Step 3 - legalities
Step 4 - manufacture
Step 5 - marketing
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Extracting Raw Materials from Plants
Step 2 Remove oil by pressing
Step 1 Crush the plant
OR step 3 Remove oil by boiling and dissolving
in a suitable solvent
or chromatography can be used
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Chromatography
Gas chromatography works by separating a mixture
and then timing how long it takes a substance to
travel through the machine. Different molecules
travel at different speeds.
How many molecules are here and which ones are
the most abundant?
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Chromatography
Chromatography can be used to test which foods
contain which ingredients. For example, consider
the dye Sudan 1, which was found in 450 foods in
2005. Which dye contains Sudan 1?
Sudan 1
As well as using chromatography, scientists also
use data relating to melting points and boiling
points to analyse the purity of a substance.
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C3h Allotropes of Carbon and Nanochemistry
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Forms of Carbon
Choose a form of carbon and research the
following

1. What properties does this form of carbon have?
2. How are the electrons arranged in this structure?
   
3. How does the structure of this form affect its
   properties?

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Allotropes of Carbon
1) Diamond very hard, doesnt conduct
electricity, very high melting point, insoluble
in water. Each carbon atom is bonded to four
other carbon atoms.
2) Graphite soft, does conduct electricity,
very high melting point, insoluble in water.
Each carbon atom is bonded to three others
causing graphite to have free electrons
3) Buckminsterfullerene 60 carbon atoms
arranged in a sphere
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Nanoscience
Nanoscience is a new branch of science that
refers to structures built from a few hundred
atoms and are 1-100nm big. They show different
properties to the same materials in bulk. They
also have a large surface area to volume ratio
and their properties could lead to new
developments in computers, building materials etc.
Task research nanoscience and find two current
and/or future applications of this science.
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Two examples of nanotechnology
The Nano Carbon Pro tennis racket uses
nanoparticles to increase its strength.
Nanotubes can be used in electrical circuits,
drug delivery systems and used as catalysts due
to their small size but large surface area