Name________________________________________________Period__________________
Study Guide: Acids, Bases, Law of Conservation of Mass
1.
2.
3.
4.
What pH range do acids have? 1-6
What pH range do bases have? 8-14
What pH do neutral substances have? 7
Describe the taste of:
a. Acids- sour
b. Bases- bitter, soapy
5. If a solution has more of a concentration of H3O+ (hydronium ions) than OH- (hydroxide ions) it is considered
to be a(n) _____acid____________________.
6. If a solution has more of a concentration of OH- (hydroxide ions) than H3O+ (hydronium ions) it is considered
to be a(n) _____base____________________.
7. If a solution has equal concentrations of OH- (hydroxide ions) and H3O+ (hydronium ions) it is considered to
be a(n) _______neutral__________________.
8. Compare strong acids to weak acids and include the following in your comparison: ionize, electrolyte, pH
Ionize completely
Do not ionize completely
Strong electrolytes
Weak Electrolytes
pH closer to 1
pH closer to 6
9. Compare strong bases to weak bases and include the following in your comparison: ionize, electrolyte, pH
ionize into a metal cation and an OHmake OH- ions by combining with water
Strong electrolytes
weak electrolytes
pH closer to 14
pH closer to 8
10. What color does litmus paper change to when placed in a base?___blue________
11. What color does litmus paper change to when placed in an acid?___red_________
12. What is an electrolyte?
A substance that can conduct electricity (allows electrons to flow through it)
13. Which are more dangerous: acids or bases? Why?
TRICK QUESTION- neither … both are dangerous if they are strong. Weak acids and bases are not
dangerous.
14. What is neutralization? What do hydronium and hydroxide ions combine to form?
A reaction between a base and an acid to form a salt and water. Hydronium donates an H+ to OH- to make H2O
15. Write a neutralization reaction that shows what happens when HCl reacts with NaCl.
HCl + NaCl  H2O + NaCl
16. In the equation below label the following: reactants, products, yield
NaHCO3 + CH3COOH  H2O + CO2 +
NaC2H3O2
yields
Reactants
products
17. What evidence was there of a chemical reaction in the baking soda and vinegar lab?
Gas bubbles, temperature change
18. Compare the combined mass before the reaction to the mass after the reaction for trial 1.
The mass went down
19. How can you account for this change in mass?
Matter DID NOT disappear… we just let some of the gas escape by leaving the reaction open to the air.
20. Explain the law of conservation of mass. Does trial 1 disprove this law? Explain.
Matter is neither created or destroyed, only changed… ie- atoms can’t appear or disappear, every atom in the products has
to be shown in the reactants and vice versa. Trial one does NOT disprove this…we just didn’t capture all of the atoms
produced.
21. Compare the changes in mass you calculated for the 1st and 2nd trials. What value would you expect to obtain
for change in mass if both trial validated (supported) the law of conservation of mass?
In trial 2, the mass stayed the same because we kept the system closed and collected all of the atoms.
22. Baking soda is a base and vinegar is an acid. What type of chemical reaction occurred when these were
combined? neutralization
23. Looking at the chemical equation in #18, why isn’t it possible for the element zinc, Zn, to appear on the
product side? Because it was not shown in the reactants.
24. During an endothermic reaction, the products have a(n) (greater/equal/less) amount of energy compared to
the reactants.
25. Which statement is true?
a. Bond breaking releases energy and bond making requires energy.
b. Bond breaking requires energy and bond making releases energy.
c. Bond breaking can either require or release energy, but bond making does not involve a change in
energy.
26. During an exothermic reaction, energy is written as a ( reactant/ product)
27. A reaction in which the bond forming energy is greater than the bond breaking energy is
a. exothermic
b. electrical
c. endothermic
(bond forming releases energy!!!)
28. What happens in a chemical reaction?
a. Atoms are destroyed.
b. Atoms are created.
c. Molecules are created.
d. Atoms are rearranged.
29. In an exothermic reaction, energy is transferred from
a. the reactants to the surroundings.
c. one reactant to another.
b. the surroundings to the reactants.
d. the container to the chemicals.
30. In an endothermic reaction, energy is transferred from
a. the reactants to the surroundings.
c. one reactant to another.
b. the surroundings to the reactants.
d. the container to the chemicals.
31. In a balanced chemical equation, the mass of the reactants is equal to the
a. atoms in a molecule
c. volume of the reactants
b. atomic numbers of the elements
d. mass of the products
32. A chemical equation is balanced by changing or adding
a. chemical symbols.
c. coefficients.
b. subscripts.
d. reactants.
Balance the following equations!
___CH4 + _2_O2  ___CO2 + _2_H2O
_2_ NaHCO3  ___H2O + ___CO2 + ___Na2CO3
_2_Mg + ___O2  _2_MgO
_2__NaCl + ___H2SO4  ___Na2SO4 + _2__HCl
_2__H2O  _2__H2 + ___O2
___C3H8 + __5_O2  _3__CO2 + _4__H2O
___KOH + ___HCl  ___KCl + ___H2O
__2_PaI5  __2_Pa + __5_I2
___Pb(NO3)2 + _2__KI  _2__KNO3 + ___PbI2