Transcript AS1.7.1About organic chemistry: hazard and risk in organic chemistry

Topic 1.7
Introductory organic chemistry
About organic chemistry: hazard and
risk in organic chemistry
Objectives - To be able to:
•appreciate the difference between hazard and risk
•understand the hazards associated with organic compounds and why
it is necessary to carry out risk assessments when dealing with
potentially hazardous materials
•suggest ways that risk can be reduced and reactions can be carried
out safely
Starter - Sketch the labels for the following hazards:
Corrosive, harmful, toxic, flammable,
dangerous to the environment
What colour are these labels?
Crowe2008
What captions appear on these labels?
What is chemistry?
Chemistry is the science concerned with the
composition, structure, and properties of matter, as well
as the changes it undergoes during chemical reactions.
Areas of chemical study
Inorganic chemistry, the study of inorganic matter
Organic chemistry, the study of organic matter
Physical chemistry,
the energy related studies of chemical systems
Analytical chemistry,
the analysis of material samples to gain an understanding
of their chemical composition and structure.
Biochemistry,
the study of substances found in biological organisms
Plus many other sub-divisions
The core principles of chemistry
Chemical Ideas:
•Understanding and explaining the ways in which
different chemicals react with one another.
How Chemists Work:
•Seeing how chemical theory and knowledge has
been developed and extended over time.
•Building your own practical skills.
Chemistry in Action:
•Use and abuse of chemicals.
•Recycling & sustainability.
•Ethics & Economics
Organic Chemistry
This is the study of the compounds of carbon, except for
carbon monoxide, carbon dioxide and the carbonates.
Why are there so many carbon compounds?
What is unusual about the way that carbon can form bonds?
•Carbon is in Group 4 and so can form four covalent bonds
•It can also form double and triple bonds
•It forms chains and rings of carbon atoms joined together
•Such chains and rings of carbon atoms are the basis for
whole families of organic molecules, such as;
hydrocarbons, carbohydrates, proteins, amino acids etc.
Hazard & Risk in organic chemistry
Hazard – the potential to do harm
Suggest some hazards in the laboratory
1. Hazards presented
by the substances
themselves
2. Hazards arising from the activities performed in
the laboratory: heating, pouring, spilling, etc.
Hazard & Risk in organic chemistry
Risk – the chance that a particular hazard
will actually cause harm.
Risk is affected by a number of things, in particular the
nature of the hazard and the level of exposure involved..
Affected by
•Expertise of person
•Quantities being used
•Conditions in which it is used
•Protective clothing & equipment used
A hazardous substance can be safe to use
if the risks are minimised
How science works – managing hazard, calculating risk
See active book p97
• Write the five steps needed to make a risk assessment
Ways of reducing risk
1. Working on a smaller scale
What is the advantage here if
(a)The substance produces harmful fumes?
(b)The reaction is exothermic?
(c)The substance needs to be poured from one
container into another?
Ways of reducing risk
2. Taking specific precautions or using alternative
techniques depending on the properties of the
hazardous substances used.
e.g. concentrated acids and alkalis are corrosive,
whereas their diluted solutions are irritants.
Many reactions can be performed using diluted
reagents, however there are certain reactions where
the concentrated chemical must be used, what
precautions could you take to minimise the risk?
Ways of reducing risk
3. Careful use of fume cupboards and personal
protection, considerably reduce the risk of
carrying out reactions using hazardous chemicals
(a) What are the benefits of carrying out a reaction
in a fume cupboard?
(b) Make a list of personal protection items that
you could use while performing an experiment.
Ways of reducing risk
4. Changing the conditions under which a reaction
takes place
How would lowering the temperature of a reacting
mixture reduce risk?
Less chance of overheating
Less chance of harmful fumes being released
Ways of reducing risk
5. Using alternative methods with less harmful substances
Sometimes it is possible to substitute a hazardous
chemical with one that is less hazardous. However, In
many cases the replacement chemicals are less
effective (e.g. slower reaction, lower yield of product).
Suggest why these methods are still used?
The risk is lower and so the disadvantages are
worthwhile.
See active book pp98/99 HSW pesticides and comparative risks
Summary Questions
1. What is the difference between hazard and
risk?
2. Why are chemical and explosives laboratories
relatively safe places to work?
3. What ethical issues would you need to consider
when deciding whether to use natural or
synthetic pesticides on a large scale?