Download Name: Date: Period: Chemistry B BENCHMARK 3 STUDY GUIDE

Name:
Date:
Period:
Chemistry B
BENCHMARK 3 STUDY GUIDE
STANDARDS ADDRESSED
UNIT 7: ACIDS & BASES
5a Students know the observable properties of acids, bases, and salt solutions.
5b Students know acids are hydrogen-ion donating and bases are hydrogen-ion accepting substances.
5c Students know strong acids and bases fully dissociate and weak acids and bases partially dissociate.
5d Students know how to use the pH scale to characterize acid and base solutions.
UNIT 8: THERMOCHEMISTRY
7a Students know how to describe temperature and heat flow in terms of the motion of molecules (or atoms).
7b Students know chemical processes can either release (exothermic) or absorb (endothermic) thermal energy.
7c Students know energy is released when a material condenses or freezes and is absorbed when a material evaporates or melts.
7d Students know how to solve problems involving heat flow and temperature changes, using known values of specific heat and latent
heat of phase change.
UNIT 9: REACTION RATES & EQUILIBRIUM
8a Students know the rate of reaction is the decrease in concentration of reactants or the increase in concentration of products with
time.
8b Students know how reaction rates depend on such factors as concentration, temperature, and pressure.
8c Students know the role a catalyst plays in increasing the reaction rate.
9a Students know how to use Le Châtelier’s principle to predict the effect of changes in concentration, temperature, and pressure.
9b Students know equilibrium is established when forward and reverse reaction rates are equal.
UNIT 10: BIOCHEMISTRY
10a Students know large molecules (polymers), such as proteins, nucleic acids, and starch, are formed by repetitive combinations of
simple subunits.
10b Students know the bonding characteristics of carbon that result in the formation of a large variety of structures ranging from
simple hydrocarbons to complex polymers and biological molecules.
10c Students know that amino acids are the building blocks of proteins.
UNIT 11: NUCLEAR CHEMISTRY
11a Students know protons and neutrons in the nucleus are held together by nuclear forces that overcome the electromagnetic repulsion
between the protons.
11c Students know some naturally occurring isotopes of elements are radioactive, as are isotopes formed in nuclear reactions.
11d Students know the three most common forms of radioactive decay (alpha, beta, and gamma) and know how the nucleus changes in
each type of decay.
11e Students know alpha, beta, and gamma radiation produce different amounts and kinds of damage in matter and have different
penetrations.
Name:
Date:
Period:
Chemistry B
UNIT 7: ACIDS & BASES
KEY VOCAB
Acid
Base
H+ / OHArrhenius
Bronsted-Lowry
Dissociation
Strong vs. weak
Neutralization
pH
electrolyte
KEY POINTS
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Acids are characterized by a sour taste, turning litmus paper red, and reacting with metals to form H2
gas.
Bases are characterized by a bitter taste, slippery feel, and turning litmus paper blue
Both acids and bases are electrolytes, meaning they can conduct electricity
ARRHENIUS
BRONSTED-LOWRY
ACID
Produces/donates H+
Produces/donates H+
BASE
Produces/donates OHTakes or accepts H+
Examples
Arrhenius base: NaOH (donates its OH-)
Bronsted-Lowry base: NH3 (takes H+ from H2O in the following equation to become NH4+)
NH3 + H2O  NH4+ + OH
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Dissociation occurs when acids, bases, or salts break apart into ions; these ions are able to conduct
electricity
o Acids dissociate to produce H+ + an anion (negative ion) (Ex: HCl  H+ + Cl-)
o Bases dissociate to produce a cation (positive ion) + OH- (Ex: NaOH  Na+ + OH-)
o Salts dissociate to produce a metal cation and a nonmetal anion (Ex: NaCl  Na+ + Cl-)
A strong acid or base dissociates completely (100%)
o Examples: hydrochloric acid (HCl), sodium hydroxide (NaOH)
A weak acid or base dissociates partially (from 0 to 99.9%)
o Examples: acetic acid (CH3COOH), ammonia (NH3)
Neutralization occurs when you react an acid and a base; they produce salt and water
o Example: HCl + NaOH  NaCl + H2O
o The pH becomes 7 (neutral)
pH is a scale from 0-14 that measure how strong an acid or base is
o anything less than 7 is an acid; more than 7 is a base
o closer to 0 = stronger acid, closer to 14 = stronger base
o each number on the pH scale is 10x stronger or weaker than the next number
Name:
Date:
Period:
Chemistry B
PRACTICE PROBLEMS
1. Why does a solution with table salt (NaCl) conduct electricity when a sugar solution (C6H12O6) doesn’t?
2. Identify each acid and base in the reactions and classify as Arrhenius or Bronsted-Lowry:
a. H2SO4 + Ca(OH)2  H2O + Ca(HSO4)2
b. H3PO4 + NH3  H2PO4- + NH4+
c. NH3 + H2O  NH4+ + OH3. Classify as acid, base, or neutral
a. Pure water
b. pH = 2
c. pH = 8
d. tastes sour
e. common household cleaners
f. turns litmus paper red
4. How do the following dissociate or neutralize?
HBr  ________ + _________
HBr + NaOH  _________ + _________
CsOH  _________ + __________
H2SO4 + Ca(OH)2  _________ + ________
NaBr  __________ + __________
H2SO4  __________ + __________
5. Which of the following solutions shows a strong acid? Weak acid? How do you know?
Name:
Date:
Period:
Chemistry B
UNIT 8: THERMOCHEMISTRY
KEY VOCAB
Heat
Temperature
Exothermic
Endothermic
Enthalpy
Specific heat
Latent heat
Heating curve
Phase change
KEY POINTS
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Temperature is a measure of how hot or cold something is based on how fast the molecules are moving,
also known as kinetic energy
o Temperature is measured in Celsius (°C) or Kelvin (K)
Gases have the highest temperature/kinetic energy, solids have the lowest temperature/kinetic energy
Heat is the transfer of energy between two objects due to a difference in temperature
o Heat is measured in Joules (J) or kilojoules (kJ)
An exothermic reaction releases heat as a product (on the right of an equation)
o Reactants  Products + Heat/Energy
o Usually, when an object gets colder (it freezes/condenses), it undergoes an exothermic process
o Ex: liquid water freezes into solid
An endothermic reaction absorbs heat as a reactant (on the left of an equation)
o Reactants + Heat/Energy  Products
o Usually, when an object gets hotter (it melts/evaporates), it undergoes an endothermic process
o Ex: a pot of water boils into gas
Specific heat is the energy required to raise the temperature of 1 gram of a substance by 1 degree
Celsius
Latent heat is the energy absorbed or released as a substance changes phases
To calculate the heat required for a substance to change temperature (specific heat) or change phase
(latent heat), you need the equations below:
o Specific heat:
q = m x Cp x ΔT
 m = mass, Cp = specific heat, ΔT = change in temperature
o Latent heat:
q = m x ΔH
 m = mass, ΔH = heat of fusion/vaporization/etc. (ΔH is usually given)
Heating curve graphs the temperature and phase changes of a substance over time as heat is added
Name:
Date:
Period:
Chemistry B
PRACTICE PROBLEMS
1. Draw the molecules in a gas, liquid, and solid, and describe how they act differently. How are they
different in terms of molecular motion? Kinetic energy? Temperature?
2. Identify the following as endothermic or exothermic:
a.
b.
c.
d.
e.
f.
g.
h.
The ice melts in a glass of water
The water freezes into ice cubes
A nuclear bomb explodes and releases energy
A car engine combusts, producing exhaust heat
An ice pack absorbs energy from your body
8H2 + S8  8H2S + 1026 J
2POCl3(g) + energy  2PCl3(g) + O2(g)
N2(g) + O2(g) + heat  2NO(g)
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
3. The specific heat (Cp) of copper is 0.4 J/oC. How much heat is needed to change the temperature of a 40
g sample of copper from 20.0 oC to 50.0 oC?
Name:
Date:
Period:
Chemistry B
4. What would the specific heat (Cp) of a substance be if it took 400J to increase the temperature of a 20 g
sample by 8 oC ?
5. Calculate the energy to melt 2 kg ice at 0 oC to water at 0 oC. (ΔHfusion of ice = 334 J/g)
6. On the heating curve above (under the key points), indicate which sections involve a substance changing
temperature and which sections involve a phase change (where temperature doesn’t change). Which of
these sections would you use the specific heat equation? Which of these sections would you use the
latent heat equation?
UNIT 9: REACTION RATES & EQUILIBRIUM
KEY VOCAB
Reaction rate
Collision theory
Reaction coordinate
Catalyst
Activation energy
Equilibrium
Le Chatelier’s Principle
KEY POINTS
 Reaction rate is defined as:
o the decrease in concentration of reactants over time
o the increase in concentration of products over time
 Reactions occur when molecules collide (collision theory)
 A reaction coordinate graphs the energy associated with a reaction
 Activation energy is the amount of energy required for a reaction to go to completion
Name:
Date:
Period:
Chemistry B
 A catalyst speeds up the reaction rate by lowering the activation energy:
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Equilibrium is established when the rate of forward reaction equals the rate of reverse reaction
The concentration of reactants and products do not change during equilibrium
Equilibrium is dynamic (reactions keep on going & do not stop)
Le Chatelier’s Principle: if a system is at equilibrium is disturbed by a change in concentration,
temperature, or pressure, the system will shift to counter this change.
o Concentration
 the equilibrium shifts away from the side you add to and towards the side you remove
from
o Temperature
 if you increase temperature, the equilibrium shifts away from the side with heat
 if you decrease temperature, the equilibrium shifts towards the side with heat
o Pressure
 If you increase the pressure, the equilibrium shifts towards the side with fewer molecules
 If you decrease the pressure, the equilibrium shifts towards the side with more molecules
PRACTICE PROBLEMS
1. As you decrease temperature, the rate of reaction _______________________.
2. As you increase concentration of reactants, the rate of reaction _______________________.
3. As you decrease pressure, the rate of reaction ___________________________.
4. What is a catalyst? How does it affect the activation energy? Draw the effect of a catalyst on the reaction
coordinate for #5 using a dotted or dashed line.
Name:
Date:
Period:
Chemistry B
5. Draw a reaction coordinate below and label: reactants, products, and activation energy
6. Use the following reaction for the next 5 questions. You can answer shift left, shift right, or no effect.
C3H8 + 5O2
⇌ 3CO + 4H O + heat
2
2
a. If I decrease the temperature, then the reaction will _________________________
b. If the pressure is increased, then the reaction will __________________________
c. If more CO2 is added to the system, then the reaction will ____________________
d. If C3H8 is removed, then the reaction will _________________________________
e. If H2O is added, then the reaction will ___________________________________
7. Predict the effect of decreasing the volume of the container for each equilibrium below:
(a) 2H2O(g) + N2(g) ↔ 2H2(g) + 2NO(g)
(b) SiO2(s) + 4HF(g) ↔ SiF4(g) + 2H2O(g)
(c) CO(g) + H2(g) ↔ C(s) + H2O(g)
8. Predict the effect of decreasing the temperature on the position of the following equilibria.
(a) H2(g) + Cl2(g) ↔ 2HCl(g) + 49.7 kJ
(b) 2NH3(g) + 37.2 kJ ↔ N2(g) + 3H2(g)
(c) CO(g) + H2O(g) ↔ CO2(g) + H2(g) + 27.2 kJ
Name:
Date:
Period:
Chemistry B
UNIT 10: BIOCHEMISTRY
KEY VOCAB
Polymer
Monomer/Subunit
Protein Amino acid
Nucleic acid Nucleotide
Starch
Glucose
KEY POINTS
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A polymer is a chemical compound consisting of repeating units called monomers (or subunits)
Proteins are polymers made out of monomers called amino acids
Nucleic acids are polymers made out of monomers called nucleotides
Starch is a polymer made out of monomers called glucose
The element carbon likes to bond with a lot of atoms because it has 4 valence electrons
Carbon can make single, double, & triple bonds
Most organic life is made out of carbon-containing compounds
PRACTICE PROBLEMS
1.
2.
3.
4.
Which of the above are subunits of protein? _________
Which of the above are monomers of starch? __________
Which of the above are subunits of nucleic acids? __________
Which of the above is a hydrocarbon? __________
Name:
Date:
Period:
Chemistry B
UNIT 11: NUCLEAR CHEMISTRY
KEY VOCAB
Force
Gravity
Electromagnetic
Strong nuclear force
Weak nuclear force
Nuclear fusion
Nuclear fission
E=mc2
Isotope
Average atomic mass
Radioactive decay
Alpha decay
Beta decay
Gamma decay
KEY POINTS
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A force is a push or a pull
Gravity is the pull or attraction between any two objects based on their mass
Electromagnetic force is the attraction between opposite charges or the repulsion between like charges
The strong nuclear force holds the nucleus of an atom together
o It is stronger than the electromagnetic repulsion between the protons that wants to pull the
nucleus apart
The weak nuclear force that makes certain elements radioactive
Nuclear fusion is when two atomic nuclei combine to form one new atom
Nuclear fission is when a heavy nucleus splits into smaller, more stable nuclei
Einstein’s equation E=mc2 describes how a small loss in mass (m) of a nucleus is converted into large
amounts of energy (E)
Isotopes are atoms of the same element with different number of neutrons
o Isotopes therefore have different atomic masses
o Radioactive isotopes have unstable nuclei that break apart over time
Radioactive decay is the spontaneous breakdown of a nucleus into a smaller nucleus and radiation
The 3 forms of radioactive decay are alpha (α), beta (β), & gamma (γ) decay
Alpha (α) decay releases an alpha particle (42He) as radiation
o Travels a few centimeters through the air
o Blocked by paper
Beta (β) decay converts a neutron into a proton and an electron (beta particle). The beta particle/electron
is released as radiation
Name:
Date:
Period:
Chemistry B
o Travels a few meters through the air
o Blocked by metal wall

Gamma (γ) decay occurs when a nucleus goes from high energy to low energy and releases gamma
rays
o most dangerous, can cause mutations in DNA and cancer
o blocked by thick walls of lead or concrete
\
PRACTICE QUESTIONS
1.
2.
3.
Rank the 4 fundamental forces from strongest to weakest.
Compare and contrast the strong nuclear and electromagnetic forces. Discuss why the strong nuclear
force prevents the nucleus of the atom from splitting apart.
How is a radioactive isotope different from a normal isotope?
Name:
Date:
Period:
Chemistry B
4.
Complete the following table:
TYPE OF RADIATION
WHAT IS RELEASED?
WHAT CAN BLOCK IT?
BETA
4
2He
Few-feet thick walls of
concrete or lead
5.
Radioactive isotopes have different uses in society and emit different forms of radiation. It’s useful
to know the different uses of radiation (and it’ll probably show on the benchmark). Identify the proper
form of radiation for each of the following uses:
a. Radioactive dating with the isotope carbon-14 is used to figure out the age of ancient artifacts or
remains. During the process, a 146C emits an electron to become a 147N. Which kind of
radioactive decay is present?
b. In household smoke detectors, the radioactive element americium-241 decays into neptunium237 like so: 24195Am -> 23793Np + 42He. Which kind of radioactive decay is present?
c. When doctors do bone scans, they use the radioactive isotope technetium-99 (99Tc). Bone that is
healing will absorb the technetium-99. 99Tc emits a relatively high-energy radiation without
releasing any particles, and the radiation is picked up by medical imaging equipment. Which
kind of radioactive decay is present?