Download Second Semester Final Review Guide

Second Semester Final Review Guide
Balancing Equations
1.
C3H8 + O2 → CO2 + H2O
2.
C + ZnO →
Zn + CO2
3. Hydrogen bromide gas reacts with oxygen gas to produce water and bromine gas. Write the balanced
chemical equation.
4. Aluminum (III) Nitrate reacts with iron (II) chloride to produce iron (II) nitrate and aluminum
chloride. Write a balanced chemical equation. (A nitrate ion is NO31-)
Types of Reactions
1. What are the four basic types of reactions and list an example for each.
2. Explain what is happening in each and be able to identify what type of reaction is taking place.
Finding the Empirical Formula based on Percent Composition
**Remember: The empirical formula is the simplest ration of atoms in a compound or molecule. Ex: C6H12O6 is
NOT an empirical formula! It would be CH2O.
To figure out the empirical formula, you need to remember the following phase: ESP gives me my subscript
marks.
1. Determine the empirical formula of a compound containing 1.723 grams of carbon, .289 grams of hydrogen, and .459 grams
of oxygen.
Element
Sample
%
Grams
Molar
Moles
Subscript
Multiplier
Size
Composition
Mass
2. Find the empirical formula of a compound, given that the compound is found to be 47.9 percent zinc and 52.1 percent
chlorine by mass.
Element
Sample
%
Grams
Molar
Moles
Subscript
Multiplier
Size
Composition
Mass
3. A 700 gram sample of an unknown compound is found. This sample is separated into 489.615
grams of iron, 210.385 grams of oxygen. The compounds molar mass is 159.697 grams/ mole.
a. What percentage of the compound is aluminum?____________
b. What percentage of the compound is oxygen?_____________
c. What percentage of the compound is sulfur?_____________
d. What is the empirical formula for the compound?______________
e. What is the molecular formula of the compound?___________
Stoichiometry
1. Find the mass of sodium required to produce 6.28 g of hydrogen gas from the reaction described by the following equation:
2 Na + 2 H2O → 2 NaOH + H2
Plan:_____________________________________________ ______________ Answer: ______________________________
2. Determine the mass of calcium hydroxide (Ca(OH)2 produced when calcium carbide (CaC2) reacts with .78 grams of water
according to the following equation:
CaC2 + 2 H2O → Ca(OH) 2 + C2H2
Plan:_____________________________________________ ______________ Answer: ______________________________
3. Identify the limiting reactant when 5.687 grams of SF4 reacts with 6.281 grams of I2O5 to produce IF5 and SO2.
5 SF4 + 2 I2O5 → 4 IF5 + 5 SO2 (NO WORK = NO CREDIT)
Word Bank
Surface Area
faster
stir
collision theory
increased
______ 1. Chemists’ main explanation for reaction rates
______ 2. When heat is added to a system, the molecules move ___________.
______ 3. When there are more molecules in a specific given area than before, the
concentration has ____________.
______ 4. The molecules group on the right below will react slower than the molecules
grouped on the left because of _____________.
______ 5. A build up of product near the reaction sites will slow the reaction. Preventing this
will increase the reaction rate. What should someone do?
Energy in Chemical Reactions
When a bond breaks, energy is (released / abosorbed). circle one
1. When a bond forms, energy is (released / abosorbed). circle one
2. When more energy is released than absorbed, the reaction is (exothermic / endothermic). circle one
3. When more energy is absorbed than released, the reaction is (exothermic / endothermic). circle one
4. The energy of an endothermic reaction would be located on the (Left / Right) circle one side of the arrow
in a chemical equation.
5. When rain drops form, the H20 molecules condense. This is an example of an (exothermic / endothermic)
process. circle one
6. Another way that scientist describe the heat transfer of a reaction is in terms of changes in enthalpy.
Enthalpy is symbolized by the letter ______.
7. (True or False) circle one Enthalpy change is calculated by the equation Enthalpy of the reactants minus
the enthalpy of the products.
8. (True or False) circle one An endothermic reaction has a positive enthalpy change.
9. How much energy will be released is 4 grams of H2O2 is used up in the following reaction.
2 H2O2 → 2 H2O + O2 +190 kJ
10. What does a catalyst do? How does it affect an energy diagram?
11. Draw the energy diagrams for an exothermic and an endothermic reaction and label the ∆H in both
of them. (Include the activation energy)
Gas Laws
Solve the following problems using the gas laws.
1. Solve for the missing variable
n = .86 moles
P=?
T = 36°C
V = 17.5 L
R = .0821
2. A gas occupies a volume of 2.45 L at a pressure of 1.03 atm and a temperature of 293K. What volume will the
gas occupy if the pressure changes to .980 atm and the temperature remains unchanged?
3. What volume would be occupied by 2.5 moles of oxygen gas (O2) at a pressure of 1.25 atm and a temperature of
45°C?
4. Use the chemical equation to answer the next question.
2NH3 + NaOCl -----> N2H4 + NaCl + H2O
Molar Masses N-14, H-1, O-16, Na-23, Cl-35.5
Hydrazine (N2H4) is an extremely dangerous product from the reaction above. It is extremely flammable and will
explode on contact with rust! How many liters of ammonia (NH3) would it take to create 3.4 grams of hydrazine?
5. Fluorine gas at 300K occupies a volume of 500mL. To what temperature should it be lowered to bring the
volume to 300mL?
Liquids/ Solubility/ Concentration
1. If 6 moles of sugar is used to make 2 L of solution, then the concentration is _________M.
2. If 3 moles of sodium acetate dissolves in 2 L of solution, then the concentration is _________M.
3. (TRICKIER NOW) If 15.8 grams of ammonia (NH3) is dissolved in water to make 2 L of solution, what is the
concentration?
4. If 5 grams of O2 is dissolved in water to make .5 L of solution, what is the concentration?
5. The amount of a solute that is able to be dissolved in a given solvent is its ________________.
6. If the solvent has dissolved as much solvent as possible at the current conditions, then it is said to be
______________________.
7. If the solvent can still dissolve more solvent at the current conditions, then it is said to be
__________________________.
8. If the solvent is overloaded and some of the solute does not dissolve, then it is said to be
_____________________________.
9. What happens to the solubility of a solid solute in a liquid solvent if the temperature of the solvent is increased?
10. What happens to the solubility of a gas solute in a liquid solvent if the temperature of the solvent is increased?
11. What happens to the boiling point of a solution as the concentration increases?
12. What would have a higher boiling point?
a. 5L of 2M sugar water
b. 10 L of 2M sugar water
c. 1L of 3M sugar water
d. 100 L of 1M sugar water
13. What would have a lower freezing point?
a. 15 grams of NaCl in 1L of water
b. 25 grams of NaCl in 1 L of water
c. 15 grams of NaCl in .5 L of water
d. 25 grams of NaCl in .5 L of water
14. What happens to the freezing point of a solution as the concentration increases?
15. If the boiling point changed 2 degrees Celsius when a student added NaCl to 500 grams of water, how much
must that student have added? Kb of water = .52
16. If the same student added 5 grams of NaCl to the 500 grams of water, what should he expect the new boiling
point to be? Kb of water = .52
Intermolecular Forces
1. Rank the strength of the four types of IMF from the weakest to the strongest. (dipole-dipole is the same
thing as ionic)
a. Metallic, dipole-dipole, hydrogen bonding, dispersion
b. Dipole-dipole, dispersion, metallic, hydrogen bonding
c. Dispersion, hydrogen bonding, dipole-dipole, metallic
d. Hydrogen bonding, dispersion, metallic, dipole-dipole
2. The type of IMF that holds together ionic compounds is called ____________.
a. Dispersion force
b. Dipole-dipole
c. Hydrogen bonding
d. Metallic bond
3. The type of IMF that holds together polar molecules involving N, O, F, and H is called _______________ .
a. Dispersion force
b. Dipole-dipole
c. Hydrogen bonding
d. Metallic bond
4. The type of IMF that holds metal atoms together is called ______________.
a. Dispersion force
b. Dipole-dipole
c. Hydrogen bonding
d. Metallic bond
5. The type of IMF that holds together non-polar molecules is called _______________.
a. Dispersion force
b. Dipole-dipole
c. Hydrogen bonding
d. Metallic bond
6. Determine if the following molecules are polar or not.
a. SiO2
b. CCl4
Polar/ non-polar (circle one)
c. NH3
Polar/ non-polar (circle one)
e. I2
Polar/ non-polar (circle one)
Polar/ non-polar (circle one)
d. S2O
Polar/ non-polar (circle one)
f. H3CCl
Polar/ non-polar (circle one)
Equilibrium
Use the following reaction to the questions
P4 (s) + 6 NO (g) + 54 kJ ↔ P4O6 (s) + 3 N2 (g)
1. What is true about the rates of the forward and reverse reaction at equilibrium?
a. equal b. constant c. both a and b
d. neither a nor b
2. What is true about the concentrations at equilibrium?
a. equal b. constant c. both a and b
d. neither a nor b
3. What is the equilibrium expression?
a. [P4O6] [N2] b. [N2] c. [N2]3
d. [NO]
6
[P4][ NO]
[NO]
[NO]
[N2]
4. Which reaction is the N2 gas a product?
a. Forward
b. backward
5. Which reaction is an exothermic reaction?
a. Forward
b. backward
6. Which direction will the reaction proceed if heated?
a. Forward
b. backward
7. Which direction will the reaction proceed if more NO is added?
a. Forward
b. backward
8. Which direction will the reaction proceed if compressed?
a. Forward
b. backward
9. Which direction will the reaction proceed if N2 is removed from the system?
a. Forward
b. backward
10. What type of reaction is it?
a. Homogeneous
b. Heterogeneous
11. If Keq = 3.6 and the experimental concentrations from the lab were [N2] = 4 M and [NO] = 2 M, is
the reaction at equilibrium? Which direction will the reaction proceed?
12. If the concentration of products is much greater than the concentrations of the reactants, what can
be said about Keq?
a. Keq is < 1
b. Keq > 1
c. Keq = 1
13. If the Keq >>1, than the reaction is said to be what?
a. Lying to the left b. Lying to the right c. dead on the spot
Acid/Base Unit
1. The Arrhenius definition of an acid says an acid
a. OH- ions are produced in water
b. can accept H+ ions
c. Can donate H+ ions
d. can dissociates to produce H+ ions in water
2. The Bronsted- Lowry definition of a base is one that
a. OH- ions are produced in water
b. can accept H+ ions
b. Can donate H+ ions
d. can dissociates to produce H+ ions in water
3. In the reaction NH4+ + NaOH → H2O + NH3 + Na+, the NH4+ acts as
a. A Bronsted acid only
b. An Arrhenius acid only
b. Both a Bronsted and Arrhenius acid
d. a Bronsted base
+
4. In the reaction HCl + H2O → H3O + Cl , the water acts as
a. A Bronsted base only
b. An Arrhenius base only
c. Both a Bronsted and Arrhenius base
d. a Bronsted acid
5. In the reaction H2PO4 + NaOH → H2O + Na3PO4, the NaOH as
a. An acid
b. a base
6. In the reaction HSO4 + H2O → H2SO4 + OH-, the HSO4- acts as
a. An acid
b. a base
7. What salt would be produced due to the following neutralization reaction?
H2CO3 + NaOH → H2O + ????
a. HCO3
b. NaO-
c. Na2CO3
d. NaCl
8. What salt would be produced due to the following neutralization reaction?
H2SO4 + Mg(OH) 2→
a. H2O
b. SO4OH
c. MgH
d. MgSO4
9. In the reaction H2SO4 + H20 → H30+ + HSO4-, what is one of the conjugate pairs?
a. acid: H2SO4
conjugate base: H20
b. acid: H20
conjugate base: H30+
c. acid: HSO4
conjugate base: H2SO4
d. acid: H2SO4
conjugate base: HSO410. If the Ka value is larger than 1, then the acid is said to be ___________.
a. Strong
b. Weak
11. If a substance prefers to dissociate into H+ ions and anions instead of remaining in its original form,
then it is said to be
a. Strong acid
b. weak acid c. strong base
d. weak base
12. What is the name of H2SO4?
a. Hydro sulfuric acid
b. Sulfuric acid
c. Sulfuroxide
d. Hydro sulfur oxide acid
13. If HCl is Hydrochloric acid, what do you think HBr would be called?
a. Hydrobromine
b. Hydrogen Bromide
c. Hydrobromic acid d. Bromic Acid
14. What happens to the pH value as [H3O+] increases?
a. Increases b. Decreases
15. An acid has a pH value of what?
a. Greater than 7
b. Less than 7
c. equal to 7
16. How many times larger is the [H3O+] at pH=1 than at pH=4?
a. 10
b. 100
c. 1,000
d. 10,000
17. List the following solutions in order of increasing H3O+ concentration.
Solution A: pH of 2
Solution B: pH of 10
Solution C: pH of 4
a) A, B, C
b) C, B, A
c) B, C, A
18. In a neutralization reaction,
a. the base in the reaction is neutralized.
b. the acid in the reaction is neutralized.
c. a salt is formed.
d. All of the above are correct.
19. Ammonia is a weak base. If the initial concentration of ammonia is 0.25 M and the equilibrium
concentration of OH- is 0.0025 M, calculate the Kb for ammonia.
B(aq) + H2O(l) → HB+(aq) + OH-(aq)
20. Sulfuric acid is a strong acid. If the initial concentration of sulfuric acid is 6.0 M and the equilibrium
concentration of H3O+ is 3.5 M, calculate the Ka for sulfuric acid.
HA(aq) + H2O(l) → H3O+(aq) + A-(aq)
21. What is the pH of sour pickles if [OH-] = 1.0 x 10-10M?
22. A volume of 15 mL of 0.2 M HBr neutralizes a 60 mL sample of NaOH solution. What is the
concentration of the NaOH solution? HBr + NaOH → H2O + NaBr
23. A volume of 20 mL of 0.25M Al(OH)3 netralizes a 75 mL sample of HCl solution. What is the
concentration of HCl? Al(OH)3 + 3HCl → 3H2O + AlCl3
REDOX
1. What happens during the oxidation process?
a. The loss of electrons
c. the loss of oxygen
b. The gain of electrons
d. the gaining of hydrogen ions
2. What happens during the reduction process?
a. The loss of electrons
c. the loss of oxygen
b. The gain of electrons
d. the gaining of hydrogen ions
3. True or False: If the oxidation process is to occur, then the reduction process must occur as well.
4. The substance containing the element that causes another element to gain electrons is called what?
a. Oxidizing agent
b. Reducing Agent
5. Write the oxidation number for the asked for element in each substance.
a. H in H2
b. Ca in CaCl2
c. O in Fe2O3
d. Hg in HgSO4 (SO4-2)
6. Write the oxidizing half reaction for the following equations. (Remember this involves single
atoms and not compounds!)
a. SiO2 + 2 C → Si + 2 CO ______________________________________
b. 2 Fe + 3 F2 → 2 FeF3 _______________________________________
7. Write the reducing half reaction for the following equations. (Remember this involves single
atoms and not compounds!)
a. 2 H2SO4 + C → CO2 + 2 SO2 + 2 H2O __________________________
b. MnO2 + 4 HCl → Cl2 + MnCl2 + 2 H2O ___________________________