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Laboratory Safety
and Matter &
Change—Unit 1PRE-AP CHEMISTRY
FELPS
Laboratory
Safety
How can we be safe in the
lab?
The laboratory can be but is not
necessarily a dangerous place.
With intelligent precautions and
a proper understanding of
techniques, the laboratory is no
more dangerous than any other
classroom.
Most of the precautions are just
common-sense practices.
How should I behave in the
lab?
Approach laboratory
work with maturity.
Never run, push, or
engage in horseplay or
practical jokes of any
kind in the laboratory.
Do not squirt other
students with the plastic
wash bottles.
What should I wear in the lab?
Wear protective eye goggles whenever working with chemicals, glassware, or open flames. You may want to wear an apron.
Restrain loose clothing, long hair, and dangling jewelry.
Footwear should cover feet completely; no open-toe shoes.
What should I do before
beginning a lab?
Study your lab assignment before
you begin the lab.
Complete all pre-lab questions.
Listen to all teacher instructions
carefully.
Is it okay to mix chemicals
together just to see what would
happen?
Unauthorized
experiments are
prohibited.
Do only those
experiments
assigned by your
teacher.
What is the correct procedure for
determining the odor of a
chemical?
Do not hold your face directly over an
open container of chemicals.
When observing the odor of a substance,
fan a small amount of the vapor toward
you by sweeping your hand over the top
of the container. This is known as
wafting.
What precautions should I take
when using glassware?
Check the condition of glassware before and
after using it. Inform your teacher of any
broken, chipped, or cracked glassware
because it should not be used.
Do not pick up broken glass with your bare
hands. Place broken glass in a specially
designated disposal container.
Only heat glassware that is made to be heated
(Pyrex or Kimex).
What precautions should I take
when handling chemicals?
Do not touch chemicals with your hands unless directed to do so.
Keep your hands away from your face.
Wash your hands thoroughly before and after work in a science laboratory, and after spill cleanups.
Never eat, drink or chew gum in a science laboratory. Never taste any chemical substances.
Always pour acids into water, not water into acid, because the heat of solution will cause the water to boil and acid to splatter. “Do as you oughter, pour acid into water.”
What precautions should I take in
order to avoid contaminating
chemicals?
Check the label of all bottles before removing the contents.
Do not return unused chemicals to reagent bottles.
Use a clean, dry scoop every time.
Put the lids back on all bottles after removing the required amount of chemical.
Place the red caps back on the dropper bottles.
What precautions should I take
when using the laboratory burners
or hot plates?
Restrain loose clothing and long hair.
Never place flammable materials near a flame.
Never reach over an exposed flame.
Never leave heat sources unattended. Turn off (unplug) equipment when not in use.
Use tongs, test-tube holders, or hot hands to handle hot laboratory equipment. (Remember, hot glass looks like cool glass.)
What precautions should I take
when heating a substance?
Always use heat-resistant (Pyrex or Kimex) glassware for heating.
When heating something in an open container such as a test tube, always point the open end of the container away from yourself and others.
What should I do if I have an
accident?
Report any accidents or injuries, no matter how minor, to your teacher.
If a chemical spills on your skin or clothing, wash it off immediately with plenty of water and notify your teacher.
If a chemical gets into your eyes or on your face, wash immediately in the eyewash fountain with plenty of water. Notify your teacher.
Clean up all spills immediately. Follow your teacher’s instructions for the correct clean-up procedures.
What should I do when I have
completed the lab?
Follow the directions given in each procedure or by your teacher for the disposal of all chemicals. Proper disposal of chemicals is necessary in order to protect the environment.
Leave your work area clean.
Clean all glassware.
Test tubes should be placed upside down in the test tube racks after being cleaned.
The table should be wiped down.
Wash your hands with soap and water at the end of each laboratory exercise.
Common Laboratory Equipment
Test Tube Rack Test Tubes
Graduated
Cylinder
Utility Clamp
N
N
Buret Clamp
Buret
Iron Ring
Forcep
s
Thermometer
Mechanical Balance
Common Laboratory Equipment
Beaker
Mortar and
Pestle Crucible and
Cover
Watch Glass
Evaporating Dish Pneumatic
Trough
Safety Goggles
Rubber Stoppers
Rubber Tubing
Test Tube Holder
Crucible Tongs
Test Tube Brush
Triangular File
Wire Gauze
Plastic Wash BottleErlenmeyer Flask
Funnel
Ring Stand
Scoopula
Clay
Triangle
Laboratory Burner
Laboratory Techniques
Using a laboratory burner
Check the burner tubing for cracks.
Attach the burner tubing to the gas valve.
Partially close the ports at the base of the barrel and the air ports.
Using a laboratory burner
Turn the gas full on, hold the striker about 5 cm above the top of the burner and proceed to light.
The gas flow may then be regulated by adjusting the gas valve until the flame has the desired height (approximately 3”)
Using a laboratory burner
The air flow may be adjusted by turning the air ports. A properly adjusted flame should have a blue inner cone. It should burn quietly and steadily.
When you are done using the burner (or if the burner goes out while you are using it), be sure to turn the burner off at the gas valve, never at the needle valve.
Heating a substance in a test tube
Check to see that the test tube is heat resistant
(Pyrex or Kimex).
Always use a test tube holder or clamp when
heating a test tube.
Never point a heated test tube at anyone,
because the liquid may splash out of the test
tube.
Never heat a test tube with a stopper in it.
Never look down into the test tube while heating
it.
Hold the test tube at an angle while heating it.
Gently move the test tube back and forth over
the flame in order to avoid heating only one spot.
Detecting the odor of a substance
Do not hold your face directly over an open container of chemicals.
When observing the odor of a substance, fan a small amount of the vapor toward you by sweeping your hand over the top of the container. This is known as wafting.
Handling solids
Never touch chemicals with your hands unless directed to do so.
Solids are usually contained in wide mouth bottles so that a spatula can be used to dip out the solid.
To transfer a solid to a test tube, place the solid onto a piece of glazed paper. Roll the paper up into a cylinder and slide it into a test tube that is lying flat on a table. Lift the test tube to a vertical position and tap the paper gently. The solid should slide down into the tube.
Decanting and transferring liquids
When transferring a liquid from a graduated cylinder to a test tube, you should hold the liquid at arm’s length with the elbows slightly bent.
Decanting and transferring liquids
Sometimes it is necessary to decant the liquid from a beaker or to transfer a caustic or corrosive liquid from a reagent bottle into a beaker.
A glass stirring rod should be used to avoid transferring solid when
decanting the liquid or to avoid drips and spills when pouring the caustic or corrosive liquid.
The stirring rod should be help against the lip of the beaker (or reagent bottle). The liquid is then poured slowly down the stirring rod.
5 Branches of
Chemistry
What is Chemistry?
Chemistry is the study of the
composition, structure, and properties
of matter and the changes it
undergoes.
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What are the Six Branches of
Chemistry?
1. Organic Chemistry
2. Inorganic Chemistry
3. Physical Chemistry
4. Analytical Chemistry
5. Biochemistry
6. Theoretical Chemistry
The six branches of chemistry often overlap.
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Organic Chemistry
Organic Chemistry is the study of most carbon containing compounds.
An organic chemist might:
create and analyze new chemicals made from carbon-containing building
blocks.
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Back to
Branches of
Chemistry
Inorganic Chemistry
Inorganic Chemistry is the study of all substances not classified as organic
chemicals, which includes the chemistry of all substances containing elements
other than carbon.
An inorganic chemist might:
study and develop new materials to improve existing products or make
new ones
determine ways to strengthen or combine materials or develop new
materials for use in a variety of products
This year you will be learning inorganic chemistry.
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Back to
Branches of
Chemistry
Physical Chemistry
Physical Chemistry is the study of the properties and changes of matter and
their relation to energy.
A physical chemist might:
develop new types of instruments to measure data.
measure the amount of energy released or absorbed in chemical
processes
study the mechanisms in which chemical reactions occur
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Back to
Branches of
Chemistry
Analytical Chemistry
Analytical Chemistry is the identification of the components and composition of
materials.
An analytical chemist might:
make measurements and calculations to solve laboratory and math-based
research problems
analyze the composition of medicines and research new combinations of
compounds to use as drugs
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Back to
Branches of
Chemistry
Biochemistry
Biochemistry is the study of the substances and processes occurring in living
things
A biochemist might:
identify enzymes and determine reaction mechanisms for biochemical
reactions
develop new foods, flavors and preservatives, and study how vitamins and
minerals are used in the body.
develop new drugs and study their effects.
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Back to
Branches of
Chemistry
Theoretical Chemistry
Theoretical Chemistry – the use of mathematics and computers to understand
the principles behind observed chemical behavior and to design and predict the
properties of new compounds.
A theoretical chemist might:
use a computer to explain the physical and chemical properties of various
compounds in terms of their molecular structures.
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Back to
Branches of
Chemistry
Scientific
Method
Scientific Method
The scientific method is a way to ask and
answer scientific questions by making
observations and doing experiments.
Scientists use the scientific method to
search for cause and effect relationships in
nature.Main
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Observations
Observations are made through the use of your senses. Your
five senses are:
Touch Hearing
Smell Taste
Sight
Observations must be specific and accurate, not relative, so that
they mean the same to everyone.
Incorrect – The burning bag smelled nasty.
Correct – The burning bag smelled similar to rotten eggs.Main
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Quantitative vs. Qualitative Observations
Observations may be qualitative or quantitative.
Qualitative Observations – factual descriptions that do not use numbers.
Example: Mr. Smith has brown hair.
Quantitative Observations – factual descriptions that use numbers.
Example: Mr. Smith is six feet tall.Main
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Inferences
Inferences are possible explanations based
upon observations and previous knowledge.
Example: You leave the movie theater and see
that the ground is wet so you infer that it rained.
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Classify each of the following statements
as observations or inferences.
1. The bird feeder is empty.
2. The birds must have eaten all the seeds in the
feeder.
3. The car has a flat tire.
4. The driver must have run over a nail.
observation
inference
observation
inferenceMain
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Steps in the Scientific Method
Step 1: Ask a Question
The scientific method starts
when you ask a question
about something that you
observe.
Ask a Question
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Steps in the Scientific Method
Step 2: Gather Information
Information can be gathered in many ways.
Some examples of ways in which information could be gathered include:
Making observations
Conducting background research
Ask a Question
Gather Information
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Steps in the Scientific Method
Step 3: Formulate a hypothesis.
A hypothesis is a tentative explanation (educated guess) for an event.
Hypothesis are sometimes written as “if-then” statements.
For example, If I eat 2 gallons of ice cream, then I will get sick.
Ask a Question
Gather Information
Formulate a Hypothesis
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Evaluating Hypotheses
A good hypothesis is one that can be tested.
Evaluate each of the following hypotheses as to whether or not they can be tested.
1. If the polar ice caps begin to melt, the amount of salt in the ocean water will change.
2. Dogs use mind control on their owners to be taken for walks and car rides.
Can be tested
Cannot be tested Main
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Steps in the Scientific Method
Step 4: Conduct an Experiment
An experiment is a controlled procedure designed to
test your hypothesis.
When you conduct an experiment, you will
manipulate variables. Variables are factors that
affect the outcome of an experiment.
It is important to manipulate only one variable at a
time, so that you will be able to identify what is
causing the outcome.
In many experiments, it is valuable to have a control,
that is a standard for comparison.
Ask a Question
Gather Information
Formulate a Hypothesis
Conduct an Experiment
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Types of Variables
An independent variable is the variable that you control or change. In the ice cream example, the independent variable is the amount of ice cream I eat.
A dependent variable is the variable that you measure. In the ice cream example, the dependent variable is whether or not I get sick.
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Identifying the Parts of an Experiment
You are asked to study the effect of temperature on the volume of a balloon. The balloon’s size increases as it is warmed.
1. What is the independent variable?
2. What is the dependent variable?
3. What factor is held constant?
4. How would you construct a control?
the temperature
The amount of air in the balloon
the size of the balloon
Use an identical balloon kept at room temperature.
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Steps in the Scientific Method
Step 5: Record and Analyze Data
Once your experiment is complete, the results should be analyzed to determine if your data supports your hypothesis.
If your data does not support your hypothesis, you will need to revise or reject your hypothesis.
Ask a Question
Gather Information
Formulate a Hypothesis
Conduct an Experiment
Record and Analyze Data
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Steps in the Scientific Method
Step 6: Report Results
Before communicating the results of an experiment to others, you should repeat the experiment several times to make sure that the first results weren’t just an accident.
Ask a Question
Gather Information
Formulate a Hypothesis
Conduct an Experiment
Record and Analyze Data
Report Results
(Conclusion)
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Models
A model is a visual, verbal, and/or mathematical explanation of experimental data.
Scientists often create models to help them test hypothesis and/or make predictions.
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Uses of Models
Models help simulate behavior of larger or smaller objects.
Ex. Model airplane
Models help predict future events.
Ex. Computer model of a storm
Models help us visualize objects.
Ex. Architectural model
Models can be used to explain structure and process.
Ex. Molecular model
Models provide experiences that might be dangerous or unavailable.
Ex. Flight Simulator
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Theory
A theory is an explanation that has
been supported by many, many
experiments. All theories are subject to
new experimental data and can be
modified.
Example: Atomic Theory
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Scientific Law
A scientific law is a concise statement that summarizes the results of a broad variety of observations and experiments and is generally accepted as true.
A law may be in words or in mathematical form.
Ex. E=mc2 Main
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Properties
of
Matter
Properties and Changes in Matter
Matter is anything that has mass and
volume.
Matter can be described in many
different ways.
One way matter can be described is
according to its chemical and physical
properties.Main
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States
of
Matter
States of Matter
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Matter exists in many different forms, and it can
be classified in many different ways.
One way that matter can be classified is
according to its physical state.
The three most common states of matter are
solids, liquids, and gases.
Properties Commonly Used to Describe
Solids, Liquids and Gases
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Fluidity – the ability of a substance to flow and
therefore conform to the outline of its container.
Compressibility – the ability of a substance to be
pressed together or compacted, thereby reducing
the volume of the substance without changing its
mass.
Rigidity – the property of a substance that
describes the inability of an object to change
shape, inflexibility or stiffness of a substance.
Properties of Solids
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The particles in a solid:
• are packed very close together.
• are held together with strong intermolecular
forces or bonds
• vibrate slowly in place
Solids:
• have a definite shape
• maintain their shape. This means they are rigid.
• have a definite volume.
• are incompressible
• are relatively dense
Properties of Liquids
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The particles in a liquid:
• are close together with some intermolecular forces.
• are able to move (slide past each other), but
movement is limited by intermolecular forces.
Liquids:
• do not have a definite shape.
• have a definite volume.
• flow and fill the bottom of a container. This means
they are not rigid.
• Are difficult to compress because there a quite a low
of particles in a small volume.
Properties of Gases
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The particles in a gas:
• are far apart
• are free to move in all directions
• Have very weak intermolecular forces of
attractionGases:
• do not have a definite shape.
• flow and expand to fill any container.
• are easily compressed
• are often low density as there are not many
particles in a large space.
Elements,
Compounds, and
Mixtures
Classifications of Matter
There are many other ways to classify
matter.
Two common ways to classify matter are
uniformity and ability to be broken down
into simpler substances.
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Elements
• Elements are pure substances that are made of
only one type of atom.
• Elements are homogeneous.
• Elements cannot be separated into simpler
substances by ordinary chemical or physical
means.
• The known elements are listed on the periodic
table.
• Chemical symbols are used to represent the
elements. Ex. C, H, N
Compounds
• Compounds are pure substances that are made of more than
one type of atom chemically combined.
• Compunds are homogeneous.
• The properties of a compound are different from those of the
elements from which it is made.
• Compounds can be broken down into their elements by
chemical means.
• The elements making up a compound are always combined
in the same ratio.
• Chemical formulas are used to represent compounds. Ex.
NaCl, C12H22O11, H2O, CO2
Mixtures
• Mixtures are physical combinations of two or more kinds of
matter, each of which retains its own identity and properties.
• Mixtures can be homogeneous or heterogeneous.
• Homogeneous mixtures are called solutions. Examples
include alloys, salt water, pure air
• Mixtures can be separated into simpler substances by
physical means. Ex. Distillation, filtration, chromatography.
• Different mixtures of the same substance can have different
compositions.
Classify each of the following as elements,
compounds or mixtures.
1. spaghetti sauce
mixture
2. table sugar
compound
3. river water
mixture
4. nitrogen gas
elementMain
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Homogeneous
materials are
uniform throughout.
Heterogeneous materials
are not uniform
throughout.
The individual
components are often
visible.
Heterogeneous materials
often settle upon standing.
Examples:
elements
compounds
solutions
alloys
Examples:
tossed salad
bowl of raisin bran Main
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Classify each of the following as
homogeneous or heterogeneous.
1. Crunchy peanut butter
heterogeneous
2. Paint
heterogeneous
3. Steel
homogeneous
4. 3% hydrogen peroxide solution
homogeneousMain
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NO
Matter
Is it uniform throughout?
NO
NO
YES
YES
YES
Solution
Homogeneous
Does it have a variable composition?
Heterogeneous Mixture
Pure Substance
Can it be separated into simpler substances?
Element Compound
Physical
and Chemical
Properties and
Changes
Properties and Changes in Matter
One way matter can be described is
according to its chemical and physical
properties.
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Properties that can be
observed or measured
without causing change to
the substance’s
composition.
Properties that relate to a
substance’s ability to
undergo changes to its
composition.
Example:
Magnesium Ribbon
is silvery-white and
is very light.
Example:
Magnesium burns in air to
produce magnesium oxide.
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Classify each of the following as either a chemical or
physical property.
1. Water boils at 100ºC.
Physical
2. Wood is flammable.
Chemical
3. Aluminum has a low density.
Physical
4. Iron rusts in a damp environment.
Chemical
5. Gasoline burns in the presence of oxygen.
ChemicalMain
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Properties that do
NOT depend on the
sample size.
Properties that DO
depend on the
sample size.Examples:
Density
Melting Point
Malleability
Examples:
Mass
Volume
Another way of separating kinds of PHYSICAL
properties is to think about whether or not the size
of the sample would affect a particular property.
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Classify each of the following as either an
intensive or an extensive physical property.
1. Boiling Point.
Intensive
2. Volume
Extensive
3. Density
Intensive
4. Mass
Extensive
5. Malleability
IntensiveMain
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Physical Changes
• Changes that do not result in the production of a
new substance are known as physical changes
• The chemical composition is not changed
during a physical change.
• Examples
folding paper
melting butter
dissolving salt in water Main
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Chemical Changes
• Changes in which one or more substances
are converted into different substances with
different chemical and physical properties.
• Chemical changes are also called chemical
reactions.
• Examples
Burning Paper
Reacting Acid with water
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Indications of a Chemical Change
• Formation of a gas (bubbling)
• Change in energy
Endothermic – energy is absorbed,
surroundings get cold
Exothermic – energy is released,
surroundings get warm
• Production of a precipitate
• Change in color or odorMain
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Endothermic vs. Exothermic Reactions
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Reaction Progress
R
P
Reaction Progress
R
P
There is an overall
absorption of energy.There is an overall release
of energy.
CH4 + 2O2 CO2 + 2H2O + energy2NaCl + energy 2Na + Cl2
Classify each of the following as
endothermic or exothermic.
1. The products have more potential energy
than the reactants
endothermic
2. When two chemicals are mixed in a beaker,
the beaker gets warm.
exothermic
3. boiling water
endothermic
4. H2 + I2 + energy → 2HI
endothermicMain
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Classify each of the following as either a
chemical change or a physical change.
1. Crushing an aluminum can
physical
2. Silver tarnishing
chemical
3. A metal chair rusts
chemical
4. Dissolving sugar in water
physical
5. Water freezing and forming ice
physicalMain
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Law of Conservation of Mass
• During a chemical change, the amount of
matter present before the reaction is equal
to the amount of matter after the reaction.
• In ordinary chemical reactions, matter can
change forms, but it cannot be created or
destroyed.
• This is known as the Law of Conservation of
Mass.Main
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Identifying Reactants and Products
• The reactants are the chemicals present
before a chemical reaction.
• The products are the chemical that are
present after a chemical reaction.
• Reactants → Products
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Identifying Reactants and Products
Examine the following chemical equation in
which sodium metal and chlorine gas react to
form solid sodium chloride.
2Na(s) + Cl2(g) → 2NaCl(s)
Identify the reactant(s).
Sodium (Na) and Chlorine (Cl2)
Identify the product(s).
Sodium Chloride (NaCl)Main
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Note: The (s) and (g) indicate the physical state of each element substance.
Identifying Reactants and Products
Examine the reverse reaction in which solid
sodium chloride is decomposed to form
sodium metal and chlorine gas.
2NaCl(s) → 2Na(s) + Cl2(g)
Identify the reactant(s).
Sodium Chloride(NaCl)
Identify the product(s).
Sodium (Na) and Chlorine (Cl2)Main
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Law of Conservation of Mass
According to the law of conservation of mass,
the total mass of the reactants of a chemical
reaction must be equal to the total mass of the
products present after a chemical reaction.
If the mass of all of the reactants and products
except one are known, the law of conservation
of mass can be used to calculate the mass of
the other substance. Main
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Law of Conservation of Mass
Hydrogen reacts with oxygen according to the
following reaction to produce water.
2H2 + O2 2H2O
How many grams of water will be produced if
4.0 g of hydrogen reacts with 32.0 g of
oxygen?
4.0 g + 32.0 g = 36.0 g Main
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Law of Conservation of Mass
Use the illustration below to determine the
amount of zinc produced.
The amount of zinc produced is
64 g + 192 g = 152 g + ?
Ans. 104 gMain
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