Name____________________________________
Block_______
Directions - Read the introduction below & complete the pre-lab questions before starting the lab.
Introduction: The science of chemistry is based upon observations. An observation is a statement based on sensory data. For example, “the liquid is clear & colorless” is an observation. “There is no change” or “nothing happened” is also an observation. Quantitative observation involves a measurement; for example “The temperature of the liquid is 96 o
C”. Qualitative observation is a general description that does not involve a measurement; for example “The liquid is hot”.
An interpretation is an explanation or opinion about what is observed. It would be an interpretation to say
(without testing) that “the clear liquid is H
2
O”. In this lab you will observe a chemical reaction & practice making as many observations as possible.
A chemical reaction is a chemical change. Reactants, starting substances will break their bonds & rearrange atoms to form new bonds & make new substances called products.
Common indicators of a chemical change are : Evolution of heat & light, increase of decrease of temperature, color change, odor change, gas evolution.
When a reaction causes an increase in temperature in the surroundings, it is considered an exothermic reaction, whereas if there is a decrease in temperature in the surroundings, the reaction is considered endothermic.
Prelab Questions : Define and give an example of each below. Use your notes or textbook. ex. Element
Compound
Mixture ex. ex.
2(aq)

3(aq)
Materials:
100 -mL graduated cylinder
100 -ml beaker
Electronic balance thermometer
Safety Precautions:
Wear safety goggles at all times.
Be careful not to get any chemical in your eyes or mouth.
Wash your hands and equipment when finished.
Copper (II) chloride is a skin/eye irritant. stirring rod spoon copper (II) chloride crystals or powder aluminum foil weighing paper
Procedure
1.
Measure 25.0 mL of water (H
2
O) in graduated cylinder and pour it into the small beaker. Record the temperature & some physical properties (descriptions) of the water in the data table. The thermometer should rest in the water without touching the bottom of the beaker.

2.
Place the weighing paper on the balance pan, and then hit the “zero” button. When the balance reads “0” use the scoopula to measure and carefully pour 2.5 g of copper (II) chloride (CuCl
2
) onto the weighing paper.
Record some physical properties(description) of the substance in the data table.
3.
Add the copper (II) chloride to the small beaker of H
2
O and stir with the wood splint. Record the temperature and your observations in the table below.
4.
Measure a 2- in 2 piece of aluminum foil (Al) & record some physical properties (descriptions) of the substance.
5a.
Loosely crumple Al into a ball and place into the mixture. Press it down with the wood splint until something begins to “occur or happen” within the beaker. Record your observations and the temperature in the table below.
5b.
While the “activity” within the beaker is occurring record your observations and the highest temperature in the table below.
6.
When all activity within the beaker has stopped, empty the contents of the container into the designated
“waste container” on Mrs. Soto’s demo table.
7.
Wash beaker & the thermometer in a soap solution, wipe your lab station with a damp cloth, throw out the coffee filter & wood splint. Wash your hands.
Data Table
System Observations Classify as Element,
Compound, or Mixture
Temperature
In Celsius
(

.1)
Step 1:
H
2
O
Step 2:
CuCl
2
Step 3
Water & copper (II) chloride
Step 4:
Al
Step 5a
Water, copper (II) chloride and aluminum foil- initially
Step 5b
Water, copper (II) chloride and aluminum foil- at the end
Analysis: Use the introductory reading and/or notes to answer the following questions
1. What is the difference between an observation and an interpretation?
2. List 2 signs of a chemical reaction that you observed in this activity.
3. Give 2 physical properties of copper (II) chloride.
4. Was energy absorbed(endothermic) or released(exothermic) in this reaction? (circle one)
5. Circle all of the quantitative observations in your data table.
6. List the chemical formulas of the reactants of the lab.

System Observations
Step 1:
H
2
O
Step 2:
CuCl
2
Step 3
Water & copper
(II) chloride
Step 4:
Al
Step 5a
Water, copper
(II) chloride and aluminum foil- initially
Step 5b
Water, copper
(II) chloride and aluminum foil- at the end
System Observations
Step 1:
H
2
O
Step 2:
CuCl
2
Step 3
Water & copper
(II) chloride
Step 4:
Al
Step 5a
Water, copper
(II) chloride and aluminum foil- initially
Step 5b
Water, copper
(II) chloride and aluminum foil- at the end
Classify as Element,
Compound, or
Mixture
Temperature
In Celsius
(

.1)
----------------
---------------
Classify as Element,
Compound, or
Mixture
Temperature
In Celsius
(

.1)
----------------
----------------

Multiple Choice: Identify the letter of choice that best completes the statement or answers the question.
_____1. Which of the following is a quantitative observation from this lab? a. the crystals are green b. the final temperature was 95.0

C
c. the temperature of the mixture increased d. a brown solid was produced
_____2. Identify which of the following “matter” was a mixture?
a. water, H
2
O c. copper(II) chloride, CuCl
2 b. aluminum, Al d. copper(II) chloride and water, CuCl
2
& H
2
O
_____3. Identify a reactant in the reaction done in this lab. a. aluminum, Al c. water, H
2
O b. aluminum chloride, AlCl d. copper, Cu
3
_____4. Which statement best describes the temperature change of the reaction. a.
The reaction was endothermic, the temperature of the surrounding increased b.
The reaction was exothermic, the temperature of the surrounding increased c.
The reaction was endothermic, the temperature of the surrounding decreased d.
The reaction was exothermic, the temperature of the surrounding decreased
_____5. Which of the following observations was not an indicator of a chemical change in this lab? a. evolution of light c. odor change b. color change d. temperature change
Multiple Choice: Identify the letter of choice that best completes the statement or answers the question.
_____1. Identify which of the following “matter” was a mixture?
a. water, H
2
O c. copper(II) chloride, CuCl
2 b. aluminum, Al d. copper(II) chloride and water, CuCl
2
& H
2
O
_____2. Which of the following is a quantitative observation from this lab? a. the crystals are green b. the final temperature was 95.0

C
c. the temperature of the mixture increased d. a brown solid was produced
_____3. Which of the following observations was not an indicator of a chemical change in this lab? a. evolution of light b. color change c. odor change d. temperature change
_____4. Which statement best describes the temperature change of the reaction. a.
The reaction was endothermic, the temperature of the surrounding increased b.
The reaction was exothermic, the temperature of the surrounding increased c.
The reaction was endothermic, the temperature of the surrounding decreased d.
The reaction was exothermic, the temperature of the surrounding decreased
_____5. Identify a reactant in the reaction done in this lab. a. aluminum, Al b. aluminum chloride, AlCl
2 c. water, H
2
O d. copper, Cu