Transcript C3 – Chemicals in Our Lives Revision

C3 – Chemicals in Our Lives
Starter
• Element or Compound?
Sulphur
S
Carbon Dioxide
CO2
Water
H2O
Chlorine
Cl2
Sulphuric Acid
H2SO4
Carbon (Buckminsterfullerene)
C60
Sodium Hydroxide
NaOH
Definitions
• Element
• Contains only one type of Atom.
• Found on the Periodic Table (of elements)
• Compound
• Consists of 2 or more elements bonded (fixed)
together
Which Elements are in the
Compounds?
Carbon Dioxide
CO2
Water
H2O
Sulphuric Acid
H2SO4
Sodium Hydroxide
NaOH
Elements, Compounds and Rocks
• Rocks are a MIXTURE of Compounds
• The most common compound is Silicon
Dioxide SiO2
• This is commonly known as Quartz or Silica
Rocks and Plate Movements
The Rock Cycle
Three Rock Types:
Sedimentary
- made from sediment
Metamorphic
– changed by heat and pressure
Igneous
– formed from Lava or Magma (molten rock)
Plate Movements
Useful Resources from Rocks
• Coal (carbon)
• Limestone (Calcium Carbonate)
• Marble (Calcium Carbonate)
• Rock Salt (Sodium Chloride)
• Metal Ores (Compounds containing Metals)
Early Chemical Industry
What’s the use in Salt?
• What can Salt be used for?
• List as many things as you can.
• Hint – For some, Think about the elements
that Salt is made from.
Uses of Salt
• Food (seasoning and preservation)
• Gritting Road (melts ice)
• Making Chlorine – Bleach
• Making Sodium Hydroxide – Soaps and Cleaners
• Making Hydrogen Gas – A Fuel
How is Salt obtained?
• Evaporation of Sea Water
• Mining of Rock salt
• Solution mining of Rock Salt
Why use salt in our food?
• Preservative (stops bacteria from growing)
• Flavour enhancer (seasoning)
• Makes food taste better / stronger
Salted Cod – Used to Preserve it
What is Risk?
• Risk depends upon 2 factors:
• Chance of something happening
• Level of harm that occurs if it does
Risk
• Actual Risk – A Risk calculated from actual
data
• Perceived Risk – A risk thought by individuals
without clear data to support it
Precautionary Principle
• If the risks or harm from an activity may be
greater than any benefit, it makes sense to
restrict or stop the activity.
• This is particularly true where the level of risk
is as yet unknown.
Salt and Health
• Risks: High Blood Pressure, Heart Disease and Strokes
• High Salt diet – Processed food with added salt
• Salt is needed – but no more than about 4g per day
• Current average intake in the UK:
• Men - 11g of salt per day
• Women - 8g of salt per day
What is an Alkali?
• Chemical Compounds that contain
HYDROXIDE ions (OH-)
• Turn Universal Indicator Blue or Purple
• Have a pH over 7, usually between 9 (weak)
and 14 (very strong)
Recognising Alkalis
Uses of Alkalis
• Making Soap
• Neutralising Soil
• Making Glass
• Dyeing Cloth
Alkali Reactions
Is it an Alkali?
Sodium Hydroxide
Is it an Alkali?
Water
Is it an Alkali?
It turns Universal
Indicator Blue
Is it an Alkali?
Potassium Hydroxide
Is it an Alkali?
Hydrochloric Acid
Is it an Alkali?
Urea (Urine)
Is it an Alkali?
Wasp Sting
Is it an Alkali?
Soapy Water
Is it an Alkali?
Milk
Is it an Alkali?
Ammonium
Hydroxide
Is it an Alkali?
Rain water
Is it an Alkali?
It turns Universal
Indicator Yellow
Is it an Alkali?
Lithium Hydroxide
Is it an Alkali?
Sulphuric Acid
Is it an Alkali?
Blood
Is it an Alkali?
Bee Sting
Is it an Alkali?
Bleach
Is it an Alkali?
Fizzy Drinks
Is it an Alkali?
Toothpaste
Acid or Alkali?
Magnesium
Hydroxide
Acid or Alkali?
It turns Universal
Indicator Blue
Is it an Alkali?
Lemon Juice
Acid or Alkali?
Vinegar
Acid or Alkali?
Drain Cleaner
Acid or Alkali?
Bar of Soap
Acid or Alkali?
Stomach Juices
Acid or Alkali?
Aluminium Hydroxide
Acid or Alkali?
It turns Universal
Indicator Yellow
Acid or Alkali?
Caesium Hydroxide
Acid or Alkali?
HCl
Acid or Alkali?
NaOH
Acid or Alkali?
KOH
Acid or Alkali?
H2SO4
Electrolysis
• Using Electricity to split up compounds into
the original element that they are made from
Chlorine
• Extracted from Salt Water by ELECTROLYSIS
• Toxic Green Coloured Gas
• Very Strong Bleach
• Why would it be added to drinking water?
Risks of Chlorine in Drinking Water
• Chlorine in drinking water can pose potential
risks – creating chemicals which are toxic or
even carcinogenic
• SO WHY ADD CHLORINE???
• Benefit outweighs the risk
Questions
• Why is it important that drinking water is treated
with Chlorine?
• Chlorine is a Toxic gas. How can it be safe to add
it to drinking water?
• What potential health risks come from Chlorine
in drinking water?
• Why do we continue to add Chlorine, despite the
risks is poses?
Electrolysis of Brine
• Brine – Solution of Salt Water
• Salt – Sodium Chloride
• Electrolysis – Splitting up compounds using
Electrical Current
Chemical Warning Signs
• Chemistry and Chemicals have their own
warning signs of potential hazards
• These help you to take the correct precautions
to ensure that you stay safe and risk is
minimised.
• What do these hazard symbols stand for?
Flammable
Toxic
Explosive
Corrosive
Harmful (h) or Irritant (i)
Oxidising
Dangerous to the Environment
Assessing Chemical Risk
• We need to know:
- How much of it is needed to cause harm
- How much will be used
- How it will be used
- Chance of escaping into the environment
- Who or what it may affect
Chemical Safety
REACH
Regulation
Evaluation
Authorisation and restriction of
Chemical Substances
Risks of Plasticisers
• uPVC – Stiff, Tough Plastic used to make many
things including Drainpipes, Doors and
Window Frames
• PVC – Can be softened by adding
PLASTICISERS. These make the plastic softer
and more flexible. Used in sheeting, coating
for wires and as a leather replacement.
Risks of Plasticisers
What does Sustainable mean?
• Using the Earth’s resources in a way that can
continue in the future
• “They won’t run out”
At the end of the Life Cycle
Life Cycle Assessment
CRADLE: What is your product? What materials is it made from?
What raw materials are used? Are they sustainable?
LIFE: What is your product used for? How long will it last? Is any
energy or chemicals used in maintaining it during its life? How
long is its life likely to be?
GRAVE: What could happen to it at the end of its life? List all the
alternatives and what would happen to it in this stage. Which
of these is the best option and why?
LCA
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