An Introduction to Chemistry: Demonstration.Name ______
Chemistry----An in-depth study at the particle level.
Describing and explaining the interaction of matter.
1. A U.S. penny is composed of atoms.
a. Describe a penny at the macroscopic level (can be seen)
Include as many details as possible.
b. The atoms in a penny at the microscopic level (particles)- focus on COPPER ATOMS
How many protons?
How many electrons?
What charge?
Describe the arrangement of protons and electrons in a copper atom.
2. “Copper” pennies will react with acid.
a. Describe an acidic solution at the particle level.
Hint: what ion is present in an acidic solution? Describe a solution.
b. “Copper” pennies and nitric acid (HNO3).
Record observations of the reaction. Include as many details as possible.
c. “Copper pennies” and hydrochloric acid (HCl).
Record observations of the reaction. Include as many details as possible.
3. Cu (s) + HNO3(aq) Cu(NO3)2(aq) + H2O (l) + NO2(g)
a. What does the (s) indicate? Describe the particles in a solid.
b. What does the (aq) indicate? Describe the particles in an ionic solution.
c. What does the (l) indicate? Describe the particles in a liquid.
d. What does the (g) indicate? Describe the particles in a gas.
e. Describe a water molecule.
f. How are water molecules different from nitrogen dioxide (NO2) molecules? Water is a liquid at room temperature while nitrogen dioxide is a gas at room temperature. What does this suggest about the attractions between the molecules?
g. Explain the appearance of the brown color.
(Think about it and propose some explanation)
h. Explain the appearance of the blue color.
(Think about it and propose some explanation)
d. Balance the equation shown above. Very challenging.
4. Cu (s) + HCl (aq) no reaction
Zn (s) + HCl (aq) ZnCl2(aq) + H2(g)
In the 1980s copper became so expensive that a penny composed entirely of copper was worth more than a penny (1¢). Consequently the U.S. mint began making copper-coated zinc pennies. The pennies dropped in the hydrochloric acid were filed to expose the zinc inside.
a. Balance the equation shown above.
b. The reaction vessel feels hot to the touch.
- When you touch the container, what happens to the particles of your hand? Use kinetic energy and temperature in your description.
- What does this suggest to you about the energy transferred by this reaction? Did the reaction transfer energy out to your hand or was energy transferred into the reaction from your hand? Explain your thinking.
c. How are copper atoms different from zinc atoms?
d. Propose an explanation for the difference in the behavior of the zinc and copper.
Chemistry will be a study of reactions and the behavior of matter composed of particles. You will be asked to visualize the particles in their constant motion and describe their subatomic particles. You will identify and describe the particles before and after a reaction and then determine and describe the changes that have occurred at the particle level. Then we will begin to explain how and why these changes occur.
ANALYSIS OF A REACTION.
Analysis is a thinking strategy, where you consider the parts and then relate them to the whole. You will ask the same set of questions for every reaction you analyze this year.
1. THE REACTANTS.
a. Identify the particles.
b. Describe the particles.
c. Describe the spacing and freedom of movement of the particles.
c. Identify and Describe the attractions between particles.
2. THE PRODUCTS.
a. Identify the particles.
b. Describe the particles.
c. Describe the spacing and freedom of movement of the particles.
c. Identify and Describe the attractions between particles.
3. THE CHANGES.
a. Select one of the elements in the reaction.
Compare its particles in the reactants (before) and the products (after).
Describe the change that occurred.
b. Repeat for each element in the reaction.
4. ENTHALPY or ENERGY. What happened in terms of energy and stability?
a. Was energy transferred into or out of the system?
b. Was the reaction endothermic or exothermic?
c. Did the energy contents of the system increase or decrease?
d. Did the products become more or less stable?
e. Is the reaction favored to occur based upon enthalpy?
5. ENTROPY or DISORDER
a. Compare the disorder (randomness) of the products and the reactants.
b. Did the disorder or entropy increase or decrease?
c. Is the reaction favored to occur based upon entropy?
ALSO----
KINETICS or RATES OF REACTION
a. Relate collisions to the occurrence of a reaction.
b. Relate collisions to the rate of a reaction.
EQUILIBRIUM and REVERSIBLE REACTIONS
a. Describe the system at equilibrium.
b. Describe the effect of disturbing equilibrium.