Ch 7 Study Guide - Chemical Reactions

Name ______Per. ______

1. Answer questions about chemical reactions a. What three things can indicate a chemical change occurred?

b. What is the general name of the substance(s) that change(s) during a reaction?

c. What happens to atoms during a chemical reaction?

d. Which is the general name of the substance(s) that results from a reaction?

e. Where in molecules is chemical energy stored?

2. Choose between Endothermic VS Exothermic reactions

a. releases energy into the surroundings -

b. absorbs energy from surroundings -

c. stores energy in bonds -

d. usually results in light or heat -

e. changes light energy into plants –

3. Choose between S- Synthesis, D- Decomposition, SR- Single Replacement, DR- Double Replacement, or C- Combustion Reactions a. Methane burns with oxygen -

b. Has 2 compounds on either side -

c. Photosynthesis -

d. 1 element is oxidized, 1 element is reduced -

e. Digestion -

f. Breaks into at least two products -

g. Makes a larger, more complex compound -

h. Results in carbon dioxide and water -

i. Using electrolysis to make H2 and O2 gases -

j. Making sodium chloride (NaCl) - k. Has a single element on either side –

4. Answer the questions about balancing reactions a. Which numbers can you change? Subscripts or Coefficients

b. What is the Law of Conservation of Matter?

c. Why do reactions need to be balanced?

d. If the reaction is balanced, the mass of the reactions equals the mass of the ______.

e. Explain the Law of Definite Proportions.

f. How do you know when a reaction is in equilibrium?

g. Balance the following reactions and identify the type of reaction. Type

____ K3PO4 + ____ HCl  ____ KCl + ____ H3PO4 ______

____ KClO3  ____ KCl + ____ O2 ______

____ Na +____ I2  ____ NaI ______

____ C3H8 + ____ O2  ____ CO2 + ____ H2O ______

____ Zn + ____ HCl ---> ____ ZnCl2 + ____ H2 ______

5. Odds & Ends a. If a substance accepts electrons, is it oxidized or reduced?

b. Name 4 factors that can speed up chemical reactions 1. 2. 3. 4.

c. What would happen to foods if we didn’t have refrigeration and how does this relate to chemical reactions?