Honors Chemistry
Lab 2: OBSERVING AND INFERRING
Name
PURPOSE
To practice making accurate and complete observations of physical and chemical processes and to learn how to
formulate hypotheses that account for these observations. We continually use our senses to make observations about
our environment. Below is a list of sensory words that are helpful when describing what are observing:
Sight words
billowing
blazing
blochy
blurred
bright
brilliant
clear
Shapes
Curved
Cylindrical
Domed
Touch words
Cold
Cool
Damp
Dry
dim
faded
faint
filmy
fluorescent
glistening
glittering
Flat
Globular
Hollow
Elastic
Fuzzy
Hot
Icy
Irregular
Lumpy
Spindly
Oily
Rough
Rubbery
Sandy
glittery
glossy
glowing
grimy
hazy
indistinct
Luminous
Split
Square
Straight
Sharp
Silky
Slippery
Smooth
misty
opalescent
opaque
shadowy
shimmering
shiny
smudged
Tapering
Thin
Tubular
Soft
Spongy
Sticky
Warm
sparkling
streaked
striped
tarnished
translucent
Wavy
Wide
Waxy
Wet
INTRODUCTION
Observations, followed by development of hypothesis, are often the first steps in a scientific method. Experiments are
then designed and carried out to test these hypotheses under controlled conditions. If the results of the initial
experiment support the hypothesis, additional testing is done to further test the hypothesis. If, however, the
experimental results do not support the original hypothesis, then the hypothesis must be changed or modified. When
the results of many, many, experiments support a hypothesis, it may become a theory. A theory is a well-tested
explanation for a broad set of observations. In this lab you will perform a series of experiments, and you will make and
record observations. You will then formulate hypotheses to explain your observations.
TERMS:
Observation
 an act or instance of noticing or perceiving.
 an act or instance of regarding attentively or watching.
 the faculty or habit of observing or noticing.
 an act or instance of viewing or noting a fact or occurrence for some scientific or other special purpose: the
observation of blood pressure under stress.
Inference
 the process of deriving the strict logical consequences of assumed premises.
 the process of arriving at some conclusion that, though it is not logically derivable from the assumed
premises, possesses some degree of probability relative to the premises.
 a proposition reached by a process of inference.
Hypothesis
 If …., then …. Statement
 a proposition, or set of propositions, set forth as an explanation for the occurrence of some specified group
of phenomena, either asserted merely as a provisional conjecture to guide investigation (working
hypothesis) or accepted as highly probable in the light of established facts.
 a proposition assumed as a premise in an argument.
 a mere assumption or guess.
Theory
 a coherent group of tested general propositions, commonly regarded as correct, that can be used as
principles of explanation and prediction for a class of phenomena: Einstein's theory of relativity.
 a proposed explanation whose status is still conjectural and subject to experimentation, in contrast to wellestablished propositions that are regarded as reporting matters of actual fact.
MATERIALS PartI
Insulated gloves
Safety goggles
Lab apron
Crucible tongs
100/150, 250-mL beakers
100-mL graduated cylinder
2 watch glasses
1 large/1 small test tube
stirring rod
Plastic wash bottle
0.1 M Silver nitrate – AgNO3
0.1 M Sodium hydroxide NaOH
3% Hydrogen peroxide
calcium acetate Ca(C2H3O2)2
Copper wire
Cornstarch
Wood splints
1 L graduated cylinder
Pipet
Ice, H2O
Dry ice, CO2
Manganese (IV) oxide, MnO2
Universal indicator solution
Distilled water, H2O
Metal spoon
Distilled H2O
SAFETY
 Wear safety goggles, nitrile gloves, closed-toed shoes and a lab apron at all times in the laboratory.
 No food or drink is allowed in the laboratory at any time.
 Do not touch the dry ice with your bare hands. It can cause frostbite. Use insulated gloves or tongs.
 Avoid contact with silver nitrate solution. It can cause temporary skin discoloration and skin burns.
 Ethanol is flammable
PROCEDURE
***NOTE: RECORD DETAILED OBSERVATIONS IN THE DATA TABLE***
Make at least 4 observations for all steps
1. Place the piece of copper wire into the small test tube. Cover the copper wire with the silver nitrate solution.
Place the test tube into a 50 ml beaker so it doesn’t fall over. Observe this system every 5 minutes during the
class period, and record your observations. When finished place waste in container waste Silver nitrate.
2. Place a piece of ice and a piece of dry ice on separate watch glasses. Observe what happens with time.
3. Fill a plastic wash bottle half-way, with distilled water. Obtain several small pieces of dry ice from the teacher.
Once you are standing at your lab table, replace the jet assembly of the wash bottle and tighten. NOTE: Direct
the jet assembly toward the sink only. Record your observations.
4. Add about 20 drops of universal indicator solution to 750 ml of distilled water in a 1-L graduated cylinder.
Record what happens when 100 ml of sodium hydroxide solution is added and the mixture is stirred. Observe
what occurs when several small pieces of dry ice are added.
5. Add 1 gram of copper I chloride to a test tube and add 10 ml of water. Stir, then touch the bottom of the test
tube.
6. At the hood, observe the 3 baggies and 3 test tubes with cornstarch water mixtures were prepared by the
teacher . Each contains 3.00g of cornstarch. Baggie/test tube 1 has 5 ml of water, baggie/test tube 2 has 7 ml of
water, and /test tube 3 has 10 ml of water. Observe what happens when each mixture is stirred either by gently
messaging the baggie or by mixing with a stirring rod in the test tube. Also note what each mixture looks line
when some of each mixture is picked up with the rod.
7. Add 5 mL of 3% hydrogen peroxide solution to a large test tube (in your lab drawer). Light a wooden splint and
gently blow it out so that it is glowing. Add a small amount (pea size) of manganese (IV) oxide powder to the
test tube containing the 3% hydrogen peroxide. Observe what happens when you insert the glowing splint into
the upper part of the test tube.
8. Observe what happens when 25 ml of calcium ethanoate solution is poured into a100ml beaker containing 25ml
of ethanol.
Pre-lab:
Read lab and enter it into your lab notebook with the proper format and include a data table to collect your
observations
Post lab ANALYSIS/CONCLUSIONS
1. For each reaction, write 1 hypothesis that could explain the behavior that you observed.
2. What is the difference between physical and chemical changes?
3. How do you know that a chemical reaction took place? Give at least 4 examples.
4. Classify the following as a physical or chemical change:
1. glass breaking
10. Melting ice cream
2. hammering wood together to build a
house
11. fireworks exploding
3. a rusting bicycle
12. squeezing oranges to make orange
juice
4. melting butter for popcorn
13. frying an egg
5. separating sand from gravel
14. pouring milk on your oatmeal
6. spoiling food
15. burning leaves
7. Freezing chocolate covered bananas
16. making salt water to gargle with
8.
17. cream being whipped
the lawn
9. corroding metals
18. burning toast
DATA/OBSERVATIONS
SYSTEM/STEP
OBSERVATIONS (IT’S ALL ABOUT THE OBSERVATIONS – BE VERY DETAILED!)
COPPER/SILVER
1.
NITRATE
2.
STEP 1
3.
4.
ICE/DRY ICE
STEP 2
1.
2.
3.
4.
DRY ICE/WASH
BOTTLE
1.
STEP 3
3.
2.
4.
H2O/UNIVERSAL
1.
INDICATOR/NaOH
2.
/ DRY ICE
3.
STEP 4
4.
Copper Ii chloride
and water
1.
Step 5
3.
2.
4.
Cornstarch
5ml/7ml/10ml
wate
1.
2.
3.
STEP 6
MnO2/H2O2
STEP 7
4.
1.
2.
3.
4.
Calcium ethonate
Step 8
1.
2.
3.
4.
Honors Chemistry
name______________________________________ period____________
Lab 2: OBSERVING AND INFERRING RUBRIC – 70 points
_____ 1. Lab entered in to table of contents (1 pt)
_____2. Lab entered properly in lab notebook(title, page number, objective, materials, procedure – 5 pts)
_____3. Lab completed by the student in the lab within one week of the lab day assigned (12 points)
_____4. Data Table drawn neatly with a straight edge or neatly cut and taped into lab book (1 pt)
_____5. Data Table completely filled out with 4 observations for steps 1-8 (16 pts)
_____6. All questions answered in complete sentences (2 points)
_____7. Post lab question 1. A hypothesis for each step that could explain the behavior you observed in step in each
step (16 pts)
_____8.Post lab question 2 (4 points)
_____9. Post lab question 3 (2 points)
_____10. Post lab question 4. (9 points)
____11.. Lab station and lab notebook clean and neat(2 pts)