Po Leung Kuk Celine Ho Yam Tong College
F.4 Chemistry
Chapter 1
2004 – 2005
What is Chemistry
1.1 What is Chemistry about?
Refer to the textbook P.3
The world around us is made up of matter( 物 質 ). Matter is anything that
occupies(佔有) space and has mass(質量). Everything we see, touch, or smell is
matter.
One particular type(某一種) of matter is called a substance. Iron, water and air are
examples of substances. Chemistry is the study of substances, about their
compositions(成份), structure(結構), properties(特性) and the change among them.
1.2 A Little History of Chemistry
Refer to the textbook P.3
In ancient(古代的) times, chemistry started mainly as metal extraction(金屬提取)
and treatment. People began to use gold, silver, mercury, copper and bronze(青銅)
over 2000 years ago.
For the years between 300 B.C to 1500 A.D., a lot of the development(發展) of
chemistry was made when chemists(化學家) attempted(嘗試) to turn cheap metals
into gold. Many metals like nickel and alloys(合金) were discovered during this
period.
1.3 Chemistry in our lives today Refer to the textbook P.4 – P.5
1.
Clothing
Synthetic(人造) textile fibres(紡織纖維), such as polyester and nylon, are
products of the petrochemical industry(石油化學工業).
2.
Food
Fertilizers(肥料) and insecticides(殺蟲劑) have greatly increased world
production of food. Food additives(食品添加劑) help to improve(改善) the
3.
taste, color and freshness of food.
Housing and daily life
Building material like metals, alloys(合金), glass and cement(水泥) come
4.
from the chemical industry. We use many different plastics that are important
products of the petrochemical industry.
Transport
Fuels of cars, aircraft and ships come from the petrochemical industry. Aero
planes are made of light and strong alloy. The rust-proofing(防銹) and
paintwork(油添) of car also involve chemistry.
5.
Medical care
Human fight disease(疾病) with drugs(藥物). Also, anesthetics(麻醉藥) and
antiseptics(消毒劑) are needed for surgeries. All these are chemical products.
1.4 The Scientific Method
Refer to the textbook P.6
Scientists work by following the scientific method(科學方法):
1. Look for scientific facts(科學事實) by the observation(觀察) of nature(性質) or
experiments.
2. Compare(比較) and classify(分類) a large number of scientific facts.
3. Try to find patterns (規律)with a group of related(相關) scientific facts.
4. Try to think of a possible(可能的) explanation for the pattern. The suggested
explanation is called a hypothesis(假設). The hypothesis should enable scientists
to make predictions(推測).
5. Design new experiments to test the hypothesis. If the observation of nature or the
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Po Leung Kuk Celine Ho Yam Tong College
F.4 Chemistry
Chapter 1
2004 – 2005
What is Chemistry
predictions fail, the hypothesis is modified(改良).
6. A well-tested and widely accepted hypothesis become a theory(學說).
7. Predictions based on a theory are tested by further experiments. If a theory cannot
always make correct predictions, it should be modified until it can. If this cannot
be done, scientists have to look for a new theory.
1.5 Observation, interpretation and prediction in chemistry Refer to the textbook
P.7 – P.8
Observation in chemistry includes four activities:
Seeing with eyes, Feeling with hands, Smelling with nose as well as Hearing with
ears. Example 1.1
1.6 Laboratory Safety
Refer to the textbook P.9 – P.12
To avoid accidents, always remember: Laboratory safety is of first importance in any
experimental work.
1. Do not work in the laboratory unless your teacher is present.
2. Follow strictly the instructions(指示) given by your teacher.
3. Never run around or play in the laboratory. Do not leave your bench(實驗枱)
4.
5.
6.
7.
8.
9.
unless it is necessary.
Dispose(棄置) solid waste in the waste bin, never in the sink.
Clean up all the spillage at once. Clean up the bench after experiment.
Report all accidents and breakages to your teacher at once.
In case any chemical gets into eyes, flush the eyes with running cold water
immediately for at least 10 minutes.
For chemical burn on skin, place the affected(受影響)area under slowly
running cold water until the pain fades(再沒有痛楚).
Take all necessary safety precaution.
Safety Precautions(安全措施)
Personal protection
1. Wear a laboratory coat if possible.
2. Wear safety spectacles(安全眼鏡) whenever doing experiment.
3. Wear rubber gloves(安全手套) when handling corrosive chemicals.
4.
5.
6.
Avoid wearing contact lenes.
Tie back long hair or ties while doing experiments.
Wash hands before leaving the laboratory.
Avoid fire and burns
1. Be familiar with the location(位置) of first aid materials(救謢用品).
2. Never place a flammable liquid(易燃液體) near a naked flame(火種). Heat
3.
4.
flammable liquids only with a water-bath, a steam-bath, an oil-bath or an
electrical heating mantle.
Never throw a lighted match or paper into a waste bin.
Place hot objects on a heat-resistant mat(耐熬檯墊), not directly on the bench.
5.
When you have no immediate use of the Bunsen burner, turn it off, or turn it to
a small luminous flame(發光火焰).
6.
Do not use bare hands to pick up a hot Bunsen burner which has “struck
back”(回擊). You should turn off the gas tap at once.
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Po Leung Kuk Celine Ho Yam Tong College
F.4 Chemistry
Chapter 1
7.
8.
2004 – 2005
What is Chemistry
Be careful of burns caused by hot apparatus (hot glass looks very similar to
cold glass).
Never look down heated test tubes or point them at any person.
Avoid chemical hazards(化學色險)
1. When handling chemicals, note any hazard warning labels( 危 險 警 告 標
籤)necessary precautions.
2.
Pay special attention when working with corrosive chemicals(especially when
hot), since these chemicals can cause chemical burns to skin and seriously
injuries(嚴重傷害) to eyes.
3.
4.
Do not eat or drink in the laboratory. Never taste any chemical or solution.
Do not breathe in vapours of chemicals unnecessarily. If you have to find the
odour of a gas, do it in a proper way. e.g. Under a fume cupboard
Use the fume cupboard for experiments involving toxic gases or vapors.
Use a pipette filler to fill a pipette when doing volumetric analysis.
5.
6.
1.7 Hazardous Chemicals Refer to the textbook P.12 – P.13
Hazardous chemicals are substance which may cause injury
to people or damage to property.
A bottle containing a hazardous chemical should display
the appropriate( 適 當 )hazard warning label(s) to warn
the user.
Hazardous nature
Examples
Safety precautions
Explosive
Substances which may
explode if ignited, heated
or under a shock or friction
Oxidizing(氧化性)
Old stocks of potassium
and sodium (turned yellow)
NH4NO3(s)
Keep away from heat and
naked flames
Avoid shock or frication
NaNO3(s) and KNO3(s)
Conc. HNO3, KMnO4
potassium permanganate,
Br2(l)
Keep away from heat and
naked flames
If concentrated acid is spilt
into eyes or onto the skin,
wash the affected area with
plenty of water
Substance reacts with
oxidizable materials to give
large amount of heat.
Flammable(易燃性)
All gaseous fuel, CH4,
Substance that may easily town gas and LPG
catch fire under normal Most Organic Liquid, ester,
alcohols and petrol
conditions
Reactive Metals, Na, K, Al
powder, Mg powder,
Phosphous
For gas
All excess gases are burned
off
Fire extinguisher standby
No flame nearby (heating
by water bath)
For liquid and solid
Fire extinguisher standby
No flame nearby (heating
by water bath)
Stored in well ventilated
place(通風地方)
Corrosive
Wear a laboratory coat,
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Po Leung Kuk Celine Ho Yam Tong College
F.4 Chemistry
Chapter 1
2004 – 2005
What is Chemistry
Substances which may
destroy living tissues upon
contact.
All conc. alkalis and acids
HCl(g), Br2, I2, KOH(s),
NaOH(s) and AgNO3(aq)
safety
spectacles
and
gloves
Perform the experiment in
fume cupboard
Avoid contact with the eyes
or skin; when accidentally
spilt into the eyes or onto
the skin, wash the affected
area with plenty of water
Irritant(剌激)
Dilute mineral acids and
alkalis
ammonia solution
Anhydrous iron(III)
chloride,
Ammonium dichromate,
potassium dichromate
Avoid contact with the eyes
or skin: when accidentally
spilt into the eyes or onto
the skin, wash the affected
area with plenty of water
Benzene,
tetrachloromethaneCCl4,
Trichloromethane
Wear a laboratory coat,
safety spectacles and
gloves
Perform the experiment in
fume cupboard
Avoid breathing in their
vapours / particles
Cl2, Br2, I2, CO, NO2, SO2
Heavy metals and their
compound, e.g. Pb, Ba, Hg
Cyanide (CN-) 山埃
Perform the experiment in
fume cupboard
Avoid breathing in their
gas / vapours / particles
Wear gloves (if gloves are
not used, wash hands
thoroughly after handling
chemicals)
Non-corrosive substances
which may cause
imflammation of the skin.
Carcinogenic(致癌)
Substances which may
cause cancers.
Toxic
Substances which may
cause serious health risk or
even death if breathed in,
swallowed, or absorbed
through the skin.
CCl4 and methanol
Harmful
Iodine
Substances which may Halogenated hydrocarbons,
cause less serious health CCl4, 1,1,1-trichloroethane
risk
Wear safety gloves
Perform experiment in
fume cupboard
If accidentally spilt into the
eyes or onto the skin, wash
the affected area with
plenty of water
The laboratory should be
well ventilated
1.8 Common chemical apparatus Refer to the textbook P.13
Many different pieces of apparatus are required when we do experiments in
laboratory. (Refer to Appendix 1 of the Laboratory Handbook for details of the uses
of the apparatus.)
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Po Leung Kuk Celine Ho Yam Tong College
F.4 Chemistry
Chapter 1
2004 – 2005
What is Chemistry
1.9 Physical and Chemical Changes
Refer to the textbook P.15 – P.18
Substances change in many way. Changes can be classified as either a physical
change or a chemical change.
Physical Change
When a substance undergoes a physical change, some of its properties are changed.
However, the substances has not changed to another one.
A physical change is a change in which no new substances are formed.
Some substances change directly from solid to gaseous state on heating. This kind of
change is called sublimation(昇華). When the vapour is cooled, it changes back to
solid directly. These substances are said to sublime. e.g. Figure 1.25 and 1.26 on
P.15.
Example I2 and Ammonium Chloride NH4Cl
Chemical Change
When a substance undergoes a chemical change, it changes to one or more new
substances.
A Chemical change is a change in which one or more new substances are formed.
Exercise Q1.4 P. 15
1.10 Properties of substances
Refer to the textbook P.16 – P.18
The properties of any substance can be classified into its physical properties or
chemical properties.
Physical properties
Physical properties of a substance are those properties that can be determined
without the substance changing into another substance.
Typical physical properties include appearance(外觀)(color and physical state),
odour (smell), taste, hardness, density, solubility, malleability (ability to be rolled
into sheets), ductility (ability to drawn into wires), electrical conductivity and
thermal conductivity.
Chemical Properties
Chemical properties of a substance are the chemical reactions of the substance, and
the respective conditions under which each reaction takes place.
For example, a piece of sodium will tarnish in air, and can react vigorously when
dropped into water.
Example 1.2 on P.18
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Po Leung Kuk Celine Ho Yam Tong College
F.4 Chemistry
Chapter 1
2004 – 2005
What is Chemistry
Assignment P.22 – P.24 Multiple choice questions and questions
Past Papers
1. Tetrachloromethane is a common solvent in the chemistry laboratory. Which of the
hazard warming labels should be displayed on a bottle of Tetrachloromethane?
2.
Which of the hazard warming labels should be attached to a bottle of liquid
bromine?
3.
Which hazard warming labels should be displayed on a bottle of concentrated nitric
acid. Explain your choice.
3 marks
4.
Which hazard warming label(s) should be put on bottles containing
a. 0.2 M sodium hydroxide solution
b. 2 M sodium hydroxide solution
c. Trichloromethane
d. tetrachloromethane
e. concentrated nitric acid
f. barium chloride
g. potassium permanganate
h. mercury
i. methanol
j. benzene
5.
If a student accidentally spills some hydrochloric acid on his hand, he should
immediately wash his hand with sodium hydroxide solution. Comment on his action.
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