Download Chemistry Quiz #2 Study Guide (Answers)

Chemistry Quiz #2 Study Guide (Answers)
1. What are the definitions to the following terms?
• Melting – the process by which a substance changes from its solid
state to its liquid state. (endothermic)
• Sublimation – The process by which a substance changes directly from
its solid state to its gas state without becoming a liquid first.
(endothermic)
• Evaporation – The process by which a substance changes from its
liquid state to its gas state. (endothermic)
• Condensation – The process by which a gas becomes a liquid.
(exothermic)
• Solidification – The process by which a liquid becomes a solid.
(exothermic)
• Deposition – The process by which a substance changes directly from
a gas state to a solid state without becoming a liquid first (opposite of
sublimation). (exothermic)
• Diffusion – the process by which molecules mix as a result of their
random motion.
• Product – All substances that are formed in a chemical reaction,
including invisible gases.
• Reactant – All substances you start with in a chemical reaction,
including invisible gases.
• Subscript – The small number in a formula that identifies the number of
atoms in each molecule. This cannot be changed.
• Coefficient – The larger number in front of a formula that identifies the
number of molecules of that specific substance. This can be changed.
• Endothermic Reaction – Energy (heat) entering a reaction (melting,
sublimation, evaporation)
• Exothermic Reaction – Energy (heat) leaving a reaction
(condensation, solidification, deposition)
2. What is the Kinetic Molecular Theory?
The theory that all molecules are in constant motion.
3. What does the Law of Conservation of Matter say?
States that energy cannot be created or destroyed, but can
change its form. The total quantity of matter and energy available
in the universe is a fixed amount, never any more or less.
4. What happens to the weight of a substance when it changes phases
(liquid  solid, solid  liquid)? Why?
Nothing happens to the weight because no molecules have been
changed. It is a physical change.
5. What happened to the weight of the steel wool when it was burned
and/or rusted? Why?
The weight of the steel wool increased because oxygen was
added to it. We did not have a valid way to measure the weight
of the oxygen in the reactant.
Refer to the equation for decomposing water to answer the questions 6 –
11.
2H2O  2H2 + O2
6. What is the reactant in this equation?
2H2O
7. What is the product in this equation?
2H2 + O2
8. How many atoms are on the reactant side of the equation?
6 atoms (4 Hydrogen & 2 Oxygen)
9. How many atoms are on the product side of the equation?
6 atoms (4 Hydrogen & 2 Oxygen)
10. How many molecules of water are on the reactant side?
2 molecules (2H2O)
11. How many molecules of oxygen are on the product side?
1 molecule (O2)
12. What are the chemical symbols for the following common elements?
a. Oxygen - O
b. Hydrogen - H
c. Nitrogen - N
d. Chlorine - Cl
e. Carbon - C
f.
Iron - Fe
g. Sodium - Na
h. Copper - Cu