Name______Block______

Lab#1: Observing a chemical reaction

Directions- Read the introduction below and complete the prelab 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 and 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 96oC”. 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 H2O”. In this lab you will observe a chemical reaction and practice making as many observations as possible.

Prelab Questions: Define and give an example of each below.

Element / ex.
Compound / ex.
Mixture / ex.
Quantitative Observation / ex.
Qualitative Observation / ex.
Reactant / ex.
Product / ex.

Materials:

100 mL Graduated Cylinder

small beaker

Electronic balance

thermometer

wood splint

scoopula

copper (II) chloride crystals or powder

aluminum foil

coffee filter

Ringstand

Test tube/thermometer clamp

Safety Precautions:

Copper (II) chloride is a skin and respiratory irritant. It is highly toxic by ingestion and inhalation

Wear goggles at all times

If contact with the skin does occur, notify your teacher and flush the area with plenty of water

Procedure

1. Measure 25 mL of H2O and pour it into the small beaker, place it on the ringstand so that the thermometer sits in the water without touching the bottom of the beaker. Record its temperature in the table below.

2. Take the coffee filter and your scoopula to the electronic balance. Place the coffee filter on the balance pan, and then hit the “tare” button. When the balance reads “0” use the scoopula to measure and carefully transfer about 3 g of copper (II) chloride onto the coffee filter.

3. Add the copper (II) chloride to the small beaker of H2O and stir with the wood splint. Record the temperature and your observations in the table below.

4. Place a 2.5 x 2.5 cm2 piece of aluminum foil that is loosely crumpled into a ball into the mixture and 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.

5. While the “activity” within the beaker is occurring record your observations and 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 Mr. Groncki’s demo table.

7. Wash beaker and the thermometer in a soap solution, wipe your lab station with a damp cloth, throw out the coffee filter and wood splint and replace with new ones from Mr. Groncki’s demo table. Return all materials to their original place and return to your seat.

Data Table

System / Observations / Classify as Element, Compound, or Mixture
Water
Water copper (II) chloride
Water, copper (II) chloride and aluminum foil- initially
Water, copper (II) chloride and aluminum foil- during

Analysis

1. What is the difference between an observation and an interpretation?

2. List 3 signs of a chemical reaction that you observed in this activity.

3. Give 2 physical properties of copper (II) chloride.

4. Was energy absorbed or released in this reaction? (circle one)

5. Circle all of the quantitative observations in your data table.

6. Which part of the procedure involved a physical change? Chemical Change?

7. List all the reactants and products for the chemical reaction in this lab below:

Reactants → Products