Multiple choice study guide
Cumulative portion:
1. Describe the structure of an atom.
Nucleus consists of positively charged protons and neutral neutrons. Negatively charged electrons orbit
in orbitals of various energy levels. The nucleus makes up the mass of the atom.
2. Atomic number is the number of ___protons_______ an atom has.
3. What are valence electrons? Outermost electrons
4. An element’s outermost energy level is determined by its _____peroid (row)__________ on the
periodic table.
5. The number of valence electrons an atom has is determined by its ___group
(column)_______________ on the periodic table.
6. Determine which groups correspond to the following electron orbitals:
s = ______1,2______________
p = ______13-18___________________
d= _________3-12_________
7. Describe the difference between a chlorine atom, Cl, and a chlorine ion Cl-.
Chlorine atom has 7 valence electrons and a chlorine ion has 8.
8. Describe the difference between a potassium atom, K, and a potassium ion K+.
Potassium atom has 1 valence electron, potassium ion has lost its lone valence electron.
9. Describe how atomic radius changes moving across the periodic table from the upper right corner
to the lower left corner.
increases
10. Describe how electronegativity changes moving from the upper right corner to the lower left
corner.
decreases
11. How does reactivity change moving down a group on the periodic table?
Mostly decreases, some exceptions
12. Metals tend to form _______+________ (+ or -) ions and nonmetals tend to form
________-_______ (+ or -) ions.
13. What is the difference between a homogeneous mixture and a heterogeneous mixture?
Homogeneous mixtures are solutions, in which solute is dissolved in solvent. They have uniform
composition. Heterogeneous mixtures do not have uniform composition.
14. Compare and contrast properties of ionic compounds with properties of molecular (covalent)
compounds.
Ionic compounds dissociate into + and – ions when then dissolve in water. They can conduct a current
when they dissolve in water.
Covalent compounds are polar or nonpolar. Polar covalent molecules are water soluble but do not
dissociate and cannot conduct an electrical current.
Review (chapters 12-18)
15. Draw label the following graphs describing the gas laws:
a. pressure vs volume
b. pressure vs temperature
c. volume vs temperature
16. What is meant by Avogadro’s Principle?
Equal volumes of gases at the same temperature and pressure contain equal numbers of particles
(moles). At STP, 1 mol = 22.4L
17. Differentiate between an endothermic and exothermic reaction. Draw graphs of each.
Endothermic require heat, exothermic release heat.
18. How does increasing the concentration of reactants influence the direction of a reaction?
Increasing the concentration of the products?
A + B
C+D
Increasing reactants, shifts the reaction right. Increasing products shifts the reactions left.
19. What factors increase reaction rate?
Increase surface area, increase temperature, presence of a catalyst, increase concentration of reactants.
20. How do catalysts alter activation energy and affect the rate of a reaction?
Catalysts lower the activation energy, increasing the rate of the reaction.
21. What is enthalpy and how is it calculated?
Heat absorbed or released during a chemical reactions. Enthalpy of products – enthalpy of reactants
22. What is chemical equilibrium?
Point at which the forward and reverse reactions are occurring at equal rates.
23. What factors increase the solubility of solids in liquids?
Increase surface area, stirring, heating
24. What factors increase the solubility of gases in liquids?
Lower temperature (cold) and increase pressure
25. What is the equilibrium expression for the following hypothetical equation?
3A + 2 B
C + 5D
[C][D]5
[A]3[B]2
26. What is a solubility curve diagram and what does it illustrate?
Shows the solubility of various concentrations of a substance at various temperatures.
(p. 493, Figure 14.15)
Final study guide (short answers)
Name:_______________________________
1. Draw a graph illustrating the change in temperature of water as it changes from a solid to a liquid
to a gas.
2. How does the change in temperature of water during a phase change differ from the change in
temperature in between phase changes?
Temperature remains constant during phase changes.
3. A sample of butane occupies 150L at 120kPa. At constant temperature, find the volume at 59 torr.
59 torr X 101.3 kPa = 7.9 kPa
1
760 torr
V1P1 = V2P2
V2 = V1P1/P2 = (150L)(120 kPa) / 7.9 kPa = 2300L
4. A gas has an original temperature of 20oC and an original pressure of 450 torr. If the volume is held
constant and the pressure of the gas changes to 710 torr, what is the new temperature?
20oC + 273K = 298K
P1 = P2
T1 T2
T2 = P2T1/P1 = (710 torr)(298K)/(450 torr) = 470K
5. a. How many molecules are in 30L of CH4 gas at STP.
30L X 1 mol
1
22.4L
X 6.02 X 1023 molecules = 8.1 X 1023 molecules
1 mol
b. Find the volume of 12.3g NO2 gas at STP.
12.3g X 1 mol X 22.4L
1
46 g
1 mol
=
6.0L
c. How many grams of CO gas are in 160 ml at STP?
160ml X 1 L
X 1 mol X 28g = 0.2g
1
1000ml
22.4 L
1 mol
6. A gas has a pressure of 730 torr, a volume of 525L and is at a temperature of 30oC. Use the Ideal
Gas Law to find how many moles of gas are in this sample.
PV=nRT
730 torr X 760 mmHg =
1
760 torr
n = PV
RT
730 mmHg
= (730 mmHg)(525 L) = 20.3 moles
(62.4)(30oC + 273)
7. Use the following hypothetical reaction to answer the next question:
4A +
3B
7C +
9D
If 300 ml of gas B reacted, find the volume of:
A: 300 ml B X 4A
1
3B
=
400 ml A
C: 300 ml B X 7C = 700 ml C
1
3B
D: 300 ml B X 9D = 900 ml D
1
3B
8. How many grams of glucose (C6H6O6) would you have to add to prepare 5L of 3.2 Molar glucose
solution?
3.2 mol X 5L X 174g =
1L
1
1 mol
2784g
9. Solution (I) is 170 ml 0.13M HCl and solution (2) is 270ml 0.16M HNO3.
a. Find the pH of each solution separately.
Solution 1: - log(0.13M) = pH = 0.9
Solution 2: -log(0.16M) = pH = 0.8
b. Find the pH of the mixture of solution 1 and 2.
Both are strong acids that completely ionize so the concentration of the acid is also the [H+].
Moles of H+ in HCl = 0.13 moles X 1L
X
170 ml = 0.0221 moles
1L
1000 ml
1
Moles of H+ in HNO3 = 0.16 moles
1L
X
1L
1000 ml
Total moles of H+ = 0.221 + 0.0432 =0.2642 moles
Total volume = 170 ml + 270 ml = 440 ml
[H+] = 0.2642 moles
440 ml
pH = - log (0.60) = .22
X
1000 ml
1L
=
0.6 M
270 ml = 0.0432 moles
1
10. After performing a titration, you must find the molarity of HNO3 if 93 ml of a 0.3M solution of
NaOH just titrates 76ml of a solution of nitric acid (HNO3) with an unknown molarity.
a. Complete and balance the neutralization equation: HNO3 + NaOH
H2O + NaNO3
b. Find the moles of the unknown solution. (HNO3)
Moles of NaOH = moles of HNO3 because there is a 1:1 mole ratio in the reaction
0.3 mol NaOH X 0.093L X 1 mol HNO3 = 0.028 mol HNO3
1L
1
1 mol NaOH
c. Determine the molarity of HNO3.
0.028 mol HNO3 X 1
= 0.37 M
1
0.076L
11. What is a solubility curve? What does it illustrate?
A solubility curve is a graph that shows the effect of temperature on the solubility of a substance.