Zusammenfassung der Ressource
C3
- Reaction Time
- The time taken between a reaction
starting and stopping
- Slow Reactions
- Long reaction times
- Rusting
- Fast Reactions
- Short reaction times
- Burning & Explosions
- A reaction stops
when one or more of
the REACTANTS is used
up
- If there is enough of
one reactant to react
with all of the other
reactant, it is in EXCESS
- The first reactant
to be used up is
called the
LIMITING
REACTANT
- MEASURING RATES
- The RATE OF
REACTION
measures the
amount of
product
formed in a
fixed period of
time
- Slow
reaction
- Small amount
of product in
a long time
- Fast Reaction
- Large
amount of
product in a
short time
- Rate increased by
- Higher temp
- particles collide more often
- And with more
energy, resulting
in more
successful
collisions each
second
- High concentration
- Particles are
closer together
and collide more
often
- High Pressure
- Crushing solids into powders
- Greater
surface area
so collisions
happen more
often
- Using a catalyst
- Alters rate
but is
unchanged
at the end
Anmerkungen:
- eg: If 1g of a catalyst is added to a reaction mixture, there is still 1g of it left after the reaction has finished.
- GAS
SYRINGE
- Measures
the volume
of gas
produced in
a reaction
- Calcium Carbonate + Hydrochloric acid --> Calcium Chloride + Water + Carbon Dioxide
- CaCO3+ 2HCl --> CaCl2 + H2O + CO2
- How It Works
Anmerkungen:
- The reaction starts when the calcium carbonate and acid are mixed together. Carbon dioxide pushes the plunger out, and its volume is read at regular intervals from the graduations on the gas syringe.
- The amount of
product formed is
DIRECTLY
PROPORTIONAL to
the amount of
limiting reactant
Anmerkungen:
- eg: If the mass of calcium carbonate is doubled, the amount of carbon dioxide also doubles
- Industrial Reactions
- Continuous Processes
- The product is
made all the
time
- Used for bulk chemicals which are needed in large amounts
- Ammonia in the Haber process
- Reactants are
continually fed
into a reaction
vessel, where
they react
together
- The ammonia produced is collected all the time
- Sulfuric acid
- Chlorine
- Batch Processes
- Not made all the time
- Wine
- Grapes are pressed to
release the grape juice,
which is then
fermented to produce wine
- Speciality Chemicals
- High value chemicals needed in small amounts
- Made on demand when a customer needs them
- Pharmaceuticals
- Raw materials
needed may be
made synthetically
using chemical
reactions or
extracted from
plants
- Several steps are needed to
extract chemicals from
plants
- 1. Crush plant material
- 2. Dissolve in a suitable solvent and then filter
- 3. Boil to evaporate the solvent
- 4. Separate the chemical by chromatography
- Making medicines
- Costs
- Research and testing
Anmerkungen:
- Suitable new substances must be identified, then tested to make sure they are safe and effective.
- Tests
Anmerkungen:
- Thousands of new substances may be made and tested in the development of a new drug.
- The 1st tests involve computer simulations and tests on cells grown in the laboratory. The most promising substances are tested on laboratory animals
- If it passes these first stages, a substance is checked for side effects in healthy human volunteers. It is then tested on a small group of patients to see if it works as expected, and then on a larger group to gather more information on it.
- All stages in development are expensive and time consuming.
- Labour costs
Anmerkungen:
- Many skilled people are needed
- Energy
Anmerkungen:
- Electricity and fuel are needed and these are expensive
- Raw materials
Anmerkungen:
- The raw materials may be rare or expensive, and complex chemical reactions may be needed to make a drug from them
- Time taken for development
Anmerkungen:
- Research and testing take a long time, and a new drug must be licenced for use.
- Marketing
Anmerkungen:
- Healthcare professionals have to be told about the drug and how to use it.
- Payback time
- The time taken to
regain money spent on
development costs
- If the patent expires
earlier than this, the
company may lose a
lot of money on the
drug
- A patent lasts up to 20
years and prevents
other companies from
making and selling the
drug
- Once it
expires,
anyone is
free to
produce
and sell it
- Impurities
- The presence of harmful impurities could make people ill
- Important to make pharmaceutical drugs as pure as possible
- Testing the purity of pharmaceuticals
Anmerkungen:
- It is tested by measuring its melting or boiling point, as impurities alter the temperature at which a drug melts or boils. The further the temperature is away from the correct one, the less pure the drug is.
- It can also be tested by TLC ( Thin Layer Chromatography). The different substances move through the a thin layer of of powder coated onto a glass or plastic plate. Colourless substances show up as spots on the plates when reacted with certain chemicals. These may be fluorescent under ultra violet light, or they may become coloured when heated.