Chemistry Evidence for Chemical Change Lab

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Questions and Answers

What are the common observations that a chemical change has occurred?

Evolution of gas, change in color, change in odor, formation of precipitate, or evolution in heat and light.

List the materials used in this experiment.

1.0M Copper(II) nitrate, 1.5M Sodium hydroxide, 1.5M Hydrochloric acid, and 5cm of aluminum foil.

What is the first procedure in this lab?

In the 250ml beaker, make a water bath by heating up until boiling approximately 100ml of water.

What is done in procedure two?

Make three marks that are three cm apart on a 13x100 mm test tube. Signup and view all the answers

What should be added to the first mark in procedure three?

1.0M Copper(II) nitrate. Signup and view all the answers

What does procedure four involve?

Add 1.5 Sodium hydroxide to the second mark and mix with a stirring rod. Signup and view all the answers

What is observed in the fourth procedure?

Formation of blue precipitate. Signup and view all the answers

What should be done in procedure five?

Put the test tube in the hot water bath and heat until no more change occurs. Signup and view all the answers

What observation is made during the fifth procedure?

Precipitate went from blue to black. Signup and view all the answers

What is the action in procedure six?

Turn off the burner, cool down, and add 1.5M hydrochloric acid to the third mark. Signup and view all the answers

What is observed in the sixth procedure?

Precipitate disappeared from black to blue. Signup and view all the answers

What should be placed in the test tube in procedure seven?

5cm of aluminum foil. Signup and view all the answers

What observations are noted in the seventh procedure?

<ol> <li>Solid red precipitate (copper), 2. Formation of gas bubbles (H2 gas), 3. Heat is released.</li> </ol> Signup and view all the answers

What is the equation for step four?

Cu(NO3)2(aq) + 2NaOH -> Cu(OH)2(s) + 2NaNO3(aq) Signup and view all the answers

What happens in step five?

Cu(OH)2(s) -> CuO(s) + H2O(l) Signup and view all the answers

Write the equation for step six.

CuO(s) + 2HCl(aq) -> CuCl2(aq) + H2O Signup and view all the answers

What is the equation for step seven A?

3CuCl2(aq) + 2Al(s) -> 2AlCl3(aq) + 3Cu(s) Signup and view all the answers

What is the equation for step seven B?

6HCl(aq) + 2Al(s) -> AlCl3(aq) + 3H2(g) Signup and view all the answers

Study Notes

Common Observations of Chemical Change

Evolution of gas bubbles indicates a chemical reaction.
Change in color can signify a new substance formation.
Change in odor may occur due to new chemicals created.
Formation of a precipitate (solid) suggests an insoluble product.
Evolution of heat and light can occur, indicating energy change.

Materials Used in the Experiment

1.0 M Copper(II) Nitrate.
1.5 M Sodium Hydroxide.
1.5 M Hydrochloric Acid.
5 cm Aluminum foil.

Experimental Procedure Overview

Procedure One: Prepare a water bath by boiling approximately 100 ml of water in a 250 ml beaker.
Procedure Two: Mark three 3 cm segments on a 13 x 100 mm test tube for measurement.
Procedure Three: Add 1.0 M Copper(II) Nitrate to the first marked line.
Procedure Four: Introduce 1.5 M Sodium Hydroxide to the second mark; mix thoroughly to yield Copper(II) Hydroxide and Sodium Nitrate.

Observations During Procedures

Fourth Procedure: A blue precipitate forms indicating Copper(II) Hydroxide.
Fifth Procedure: Heat the test tube; the precipitate transitions from blue to black (indicating the formation of Copper(II) Oxide).
Sixth Procedure: Add 1.5 M Hydrochloric Acid to the third mark; the black precipitate disappears, changing back to blue as Copper(II) Chloride is formed along with water.
Seventh Procedure: Insert Aluminum foil; monitor for temperature changes. This results in:
- Solid red precipitate indicating the formation of Copper.
- Formation of hydrogen gas bubbles.
- Release of heat.

Chemical Equations Involved

Step Four Equation:
- Cu(NO3)2(aq) + 2 NaOH → Cu(OH)2(s) + 2 NaNO3(aq) (Double displacement reaction).
Step Five Equation:
- Cu(OH)2(s) → CuO(s) + H2O(l) (Decomposition reaction).
Step Six Equation:
- CuO(s) + 2 HCl(aq) → CuCl2(aq) + H2O (Double displacement reaction).
Step Seven A Equation:
- 3 CuCl2(aq) + 2 Al(s) → 2 AlCl3(aq) + 3 Cu(s) (Single displacement reaction).
Step Seven B Equation:
- 6 HCl(aq) + 2 Al(s) → AlCl3(aq) + 3 H2(g) (Single displacement reaction).

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Description

Explore the fundamentals of chemical changes through this lab flashcard quiz. Learn about the common observations indicating a chemical change, the materials used, and the step-by-step procedures involved. Perfect for students studying chemistry and lab techniques.