General Physical Science
Semester #2
Exam Date: April 15 (A day), April 16 (B day)
Unit 3: Chemical Reactions
Oregon State Content Standards
H.2P.1 Explain how chemical reactions result from the making and breaking of bonds in a process that absorbs or releases energy.
Explain how different factors can affect the rate of a chemical reaction.
H.2P.2 Explain how physical and chemical changes demonstrate the law of conservation of mass.
H.2P.3 Describe the interactions of energy and matter including the law of conservation of energy.
Objectives:
Meeting benchmark
1. I will be able to distinguish between physical changes and chemical changes in matter using examples from
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everyday life.
I will be able to list evidence for chemical change and physical change and highlight the difference.
I will be able to write and balance chemical equations.
I will be able to explain the law of conservation of mass.
I will be able to explain how balancing chemical equations supports the principle of conservation of atoms.
I will be able to explain the difference between exothermic and endothermic reactions in terms of energy.
Exceeding benchmark
1. I will be able to balance chemical equations which involve complex molecules.
2. To show my ability to exceed the benchmarks I will use words, drawing, mathematical relationships or other
methods to further analyze patterns and/or relationships in the benchmarks.
Vocabulary
Chemical change: the breaking and reforming of chemical bonds to make new substances. Atoms are rearranged.
Physical change: change in physical properties (size, shape, state) of a substance. No change in chemical composition.
Reactant: a substance that enters into and is altered in a chemical reaction.
Product: a substance that is produced in a chemical reaction from reactants.
Chemical equation: chemical formulas and symbols that represent a chemical reaction.
Balanced equation: occurs when the number and type of atoms on the reactants’ and products’ side of a chemical
equation are equal.
Subscript: a number in a chemical formula that shows the number of a type of atom.
Coefficient: number placed in front of chemical formula to make the number of atoms on each side of equation equal.
Law of Conservation of Mass: states that the total mass of products is equal to the total mass of the reactants.
Principle of Conservation of Atoms: states that the number of each type of atom on the reactants side of a chemical
equation must be equal to the number of each type of atom on the products side of the chemical equation.
Endothermic reaction: a reaction in which more energy is required than is released. (gets cold)
Exothermic reaction: a reaction in which more energy is released than is required. (gets hot)
Homework for this unit:
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Read 353-356 Concept Review #1-4 on 370
Read 357-362 Problems #5-11 on pg 371
Concept Review #1,3,4 on page 383.
Review questions (back of this page)
Balancing equations worksheet
Conservation of Mass Lab Report (20 points)
1. What does the Law of Conservation of Mass state?
2. What does the Principle of Conservation of Atoms state?
3. Why do we balance chemical equations?
4. Is mashing up a potato to make mashed potatoes an example of a physical
change or a chemical change?
5. Fill in the blanks. Physical change is a change in ______, ______, or ______. No
new ______ are formed.
6. What are the reactants in this equation? Fe + O2  Fe2O3
7. Balance the equation ___ Fe +___ O2  ___ Fe2O3
8. How many atoms of Oxygen are there?
Fe2O3 _____
9. How many atoms of Oxygen are there now? 2Fe2O3 _______
10. How many atoms of Oxygen are there? 3B2(SO4)3
11. Balance the equation
____Na + ____ Cl2  ____ NaCl
12. Balance the equation (Hint: start by Balancing the Hydrogens)
_____ CO2 + ____H2O  ____ C6H12O6 + ____ O2
13. What is one of the products in question #12?