Chemistry Exam Notes

Exam Information

General Information

• Items to Bring:
  • Sharpened pencils and eraser (no sharing allowed).
  • Scientific or graphing calculator (no loaners available).
  • 3” x 5” index card.
• Supplied Materials:
  • Periodic table and charts.
  • Formulas and constants.

Index Card Requirements

• Name and period in the upper right corner on the front side.
• Reuse of first semester card is encouraged, with additions on the back.
• Content: Write/type anything, but no worked-out example problems.
• Must be an actual index card (not paper cut to size).
• No special devices to read the card.
• The index card must be turned in at the end of the exam to receive two points.

Exam Format

• Total: 90 points, weighted to equal 15% of the semester grade.
  • 50 multiple-choice points (approximately 25 from 1st semester).
  • 40 free-response points (all from 2nd semester).

Provided Formulas and Constants

• General:
  • 1 \text{ mol} = 6.02 \times 10^{23} \text{ particles} = \text{molar mass in g} = \text{molar volume (22.4 L @ STP)}
• Thermochemistry:
  • \Delta H = \Sigma BE{\text{reactants}} - \Sigma BE{\text{products}}
  • q = m \cdot C_p \cdot \Delta T
  • q{\text{sys}} + q{\text{surr}} = 0
  • For water:
    • C_p \text{ (water)} = 4.184 \frac{\text{J}}{\text{g} \cdot {}^{\circ}\text{C}}
    • C_p \text{ (ice)} = 2.03 \frac{\text{J}}{\text{g} \cdot {}^{\circ}\text{C}}
    • C_p \text{ (steam)} = 2.01 \frac{\text{J}}{\text{g} \cdot {}^{\circ}\text{C}}
    • \Delta H_{\text{fus}} = 6.01 \frac{\text{kJ}}{\text{mol}}
    • \Delta H_{\text{vap}} = 40.7 \frac{\text{kJ}}{\text{mol}}
• Gas Laws:
  • PV = nRT
  • R = 8.31 \frac{\text{J}}{\text{mol} \cdot \text{K}} = 0.0821 \frac{\text{L} \cdot \text{atm}}{\text{mol} \cdot \text{K}} = 62.4 \frac{\text{L} \cdot \text{mmHg}}{\text{mol} \cdot \text{K}} = 62.4 \frac{\text{L} \cdot \text{torr}}{\text{mol} \cdot \text{K}}
• Solutions:
  • M1V1 = M2V2
• Acids, Bases & Neutralization:
  • pH = -\log [H^+]
  • pOH = -\log [OH^-]
  • pH + pOH = 14
  • [H^+][OH^-] = 1.0 \times 10^{-14}
  • MA \cdot VA = MB \cdot VB

Review Method Suggestions

• Multiple Choice:
  • Every MC question on the exam is somewhere on the list provided in the material.
  • Do the Review Kahoot from class review and review the bulleted point below for each unit
• Free Response:
  • Complete the following Review Problems (answer key posted separately).
  • Print problems on paper, then sit down with pencil, calculator, exam card, white periodic table/reference charts and do them manually (not electronically on your iPad)
• Other hints:
  • Write a whole page of notes about everything you wish you could fit on the one side of the notecard. Then, from that list, write down only the essentials. The act of writing may be your best study method.
  • Other methods include making flashcards, quizlets, slide decks, mind maps, quiz by a friend (or tutor, sibling or parent), take notes from the online textbook.

Topics/Skills for Multiple Choice

• Write down hints for them that you need to put on your 3” x 5” index card
• It is possible that there are more than one question linked to the bullet points below
• The learning targets are provided for each so that you can go back to the Kahoot or FRQ practice on the test study guides or to re-watch a specific LT video

Semester 1

• Distinguish examples of matter (i.e. solids, liquids, gases) from energy (i.e. light, heat, microwaves) (LT 1B, 2C, 5A)
• Identify examples of physical and chemical properties/changes (LT 1B)
• State the formula and calculate the density of a substance given mass and volume (LT 1D)
• Compare and contrast protons, electrons and neutrons in terms of charge, size, location in the atom, and what each determines for an atom (i.e. # protons = identity, # electrons = physical and chemical properties, neutrons = isotope) (LT 2D)
• Explain the arrangement of the modern periodic table, i.e. increasing atomic number, family names, main electrons blocks (s, p, d, f) (LT 2F)
• Identify and name the period (i.e. row) and family/group (i.e. column) of an element (LT 2F)
• Use the periodic table to classify an element as a metal, nonmetal or metalloid and give its state at room temperatures (LT 2F)
• Know the seven diatomic elements, i.e. N2, O2, F2, Cl2, Br2, I2, H_2 (LT 2F)
• Identify the type of particle emitted by alpha (i.e. He nucleus) and beta radiation (i.e. electron) and how the nucleus of the atom changes due to this (LT 2G)
• Use the periodic table to write the electron configuration for an element (LT 3B)
• Explain the meaning of electron configuration notation, i.e. what do each of the numbers and letter in “2p5” mean (LT 3A, 3B)
• Rank energy levels/orbitals for electrons from lowest to highest energy (LT 3A, 3B)
• Use the periodic table to determine periodic trends of atomic radius (LT 3D)
• Use the periodic table to state the number of valence electrons for an element and how many it would need to achieve a noble-gas configuration (LT 3E, 3F)
• Explain how ions form and from what sublevels electrons are lost/gained for a given atom (LT 3E)
• Distinguish a cation from an anion (LT 3E)
• Calculate the volume in milliliters of a stock solution needed to perform a dilution with the formula M1 \cdot V1 = M2 \cdot V2 (LT 8C)
• Write the correct formula and name for ionic and covalent compounds (LT 3E, 3F)
• Determine whether a pair of elements will form an ionic bond (i.e. metal & nonmetal together) or a covalent bond (i.e. two nonmetals) (LT 3E, 3F)
• Draw simple Lewis structures for single bonded substances that obey the octet rule, i.e. H2O, NH3, CH_4 and apply the VSEPR chart to identify the molecular geometry of common molecules (LT 3G)
• Balance chemical equations and that this process makes atoms/mass equal on both sides (LT 4A, 4B)
• Interpret the coefficients in a chemical equation in terms of particles, moles, and masses (LT 4C)
• Identify the representative particles for monatomic elements (i.e. atoms), diatomic elements and molecular compounds, (i.e. molecules), and ionic compounds (i.e. formula units) (LT 4C)
• Classify chemical reactions as either combination, decomposition, single replacement, double replacement or combustion (LT 4B)
• Show how the law of conservation of mass is satisfied by a balanced chemical equation (i.e the mass of reactants = the mass of products) (LT 4C)
• Use the coefficients of a balanced chemical equation to determine the mole ratios of reactants and products (LT 4E)

Unit 5 Energy

• Compare and contrast exothermic and endothermic processes for both chemical reactions and physical processes (LT 5B)
• Evaluate a potential energy diagram to compare the energy of reactants vs. products, identity the \Delta H and activation energy (LT 5C)
• Apply the first law of conservation of energy to compare heat flow between system and surroundings (LT 5E, 5G)
• Compare the specific heat capacity of substances and the temperature change the same mass would undergo (LT 5E)
• Explain what is happening during a state change in terms of temperature and heat as expressed on a heating curve (LT 5G)
• Calculate the enthalpy change for a specific mass of water to undergo a state change (LT 5G)

Unit 6 Gases and the Earth’s Atmosphere

• Use the kinetic molecular theory to describe the particle, microscopic nature of a gas (LT 6A)
• Apply the gas law relationships to explain how temperature, pressure, volume and the number of moles will change as conditions change (LT 6A, 6B)

Unit 7 Climate Change

• Describe what is meant by Earth’s Energy Budget and relate it to trends in greenhouse gases, Earth’s surface albedo, and human influences on it since the industrial revolution (LT 7B, 7D)
• Distinguish between positive and negative feedback loops and explain how they affect the Earth system (LT 7C)
• Describe the carbon cycle and its role in the regulation of Earth’s climate, especially anthropogenic (human) influences (LT 7A, 7B)
• Identify solutions for reducing atmospheric carbon dioxide concentrations by both supporting sinks and reducing sources (LT 7A)

Unit 8 Water and Earth’s Oceans

• Explain the chemical nature of the water molecule and identify some distinguishing properties it has because of its chemical nature (LT 8A, 8B)
• Calculate the molarity of a solution given solute mass and total volume of solution (LT 8C)
• Compare and contrast the characteristics of acids and bases (LT 8E)
• Calculate the pH an acid given [H+] (LT 8F)
• Identify anthropogenic (human) activities that a linked to ocean acidification, i.e. decreasing pH of oceans (LT 8G)

Free Response Practice Problems

• To receive full credit on problems, show all work including formula used/plug-in numbers, units throughout, answers rounded for correct significant figures, correct final unit and box around it.
• Partial credit will be given, so attempt all questions.
• It is recommended that as you go through these questions, you write down hints for them that you need to put on your 3” x 5” index card. Some of these will be only asked on multiple choice.
• The learning targets are provided for each so that you can go back to the Kahoot or FRQ practice on the unit test study guides or to re-watch a specific LT video

1. Use the following balanced equation for the combustion of butane gas to answer the following questions:
   2C4H{10(g)} + 13O{2(g)} \rightarrow 8CO{2(g)} + 10H2O{(g)} + 5718 \text{ kJ}
   a) If 25.0 g of butane reacts, what mass in grams of CO_2 is produced? (LT 4E) (hint: 3-step mass to mass problem)
   b) What is the enthalpy change in kJ if 25.0 g of butane reacts? (LT 5B) (hint: 2-step mass to energy problem)
   c) Is this reaction endothermic or exothermic? How do you know, i.e. cite evidence, and what does this mean? (LT 5C)

2. At what temperature in ^{\circ}C will 8.00 g of nitrogen (N_2) gas exert a pressure of 6.00 atm in a 1.85-L cylinder tank? (LT 6C)

   Variables list: Formula / Plug-in with boxed answer:

3. Use the following data table for the next two questions:

   a) The accepted value for the specific heat of aluminum is 0.902 J/g^{\circ}C. Write a paragraph in the form of claim, evidence, reasoning using the lines below to predict which substance is most likely aluminum. Clearly show calculations for all three substances in the following box including the formula used. (LT 5E)

   b) Give two different and specific types of evidence (i.e. physical or chemical properties) that you could gather to support your claim that the sample you chose is aluminum? (LT 5E, 8B)

   	Mass	Heat absorbed	Temperature change	Specific Heat Calculation Formula:
   Sample A	20.34 g	191.8 J	73.10 ^{\circ}C
   Sample B	11.53 g	264.6 J	25.50 ^{\circ}C
   Sample C	28.11 g	675.0 J	5.80 ^{\circ}C

   i)

   ii)

4. a) How much heat in kJ would be released to condense a 35.5 g sample of steam to liquid water at 100oC? (LT 5G)

   b) What is the heat change in J to cool a 35.5 g sample of water from 100.0oC to 60.0oC? (LT 5G)

5. a) Looking at the graph on the right, how has the concentration of greenhouse gases in the atmosphere changed since the industrial revolution (1760)? (LT 7A, 7B)

   b) Identify one anthropogenic (human) activity that releases the greenhouse gases into the atmosphere. (LT 7B)

   Greenhouse Gas	Anthropogenic (Human) Source
   carbon dioxide (CO_2)
   methane (CH_4)
   nitrous oxide (N_2O)

   c) Identify & describe two ways humans are altering the carbon cycle. Refer to the fluxes and sources/sinks in the diagram on the right. (LT 7A)

   d) Explain how one of these human activities is connected to the trend in the data seen in the graph in question 9 above. (LT 7A, 7B, 7C)

6. Evaluate the following Lewis Structures and

   • identify each chemical structure - nonpolar, polar or ionic
   • give the most important type of IMF - dispersion, dipole, hydrogen bonds, ionic
   • determine if each will dissolve in water (remember: “like dissolves like”) - yes or no

   (LT 8B)

   a) propane (C3H8)

   chemical structure: IMF: _ dissolves in water?: _

   b) calcium oxide (CaO)

   chemical structure: IMF: _ dissolves in water?: _

   3) methanol (CH_3OH)

   chemical structure: IMF: _ dissolves in water?: _

   4) iodine chloride (ICl)

   chemical structure: IMF: _ dissolves in water?: _

7. What mass in grams of KClO_3 must be dissolved in 275 mL of water to make a 0.500M solution? (LT 8C)

   Variables list: Formula / Plug-in with boxed answer:

8. Use the following chemical equation to predict the shift in equilibrium. (LT 8D)

   2 BrF{5 (g)} + \text{heat} \rightleftharpoons Br{2 (g)} + 5 F_{2 (g)}

   Stress on system:	System would: (circle correct)	Product yield would:
   a) Adding BrF_5 to the system	left / right	decrease / increase
   b) Removing F_2 from the system	left / right	decrease / increase
   c) Increasing the volume of the container	left / right	decrease / increase
   d) Decreasing the temperature of the system	left / right	decrease / increase

9. a) What is the pH of a 1.50 \times 10^{-3} M solution of HNO_{3(aq)}? Name this substance. Is it an acid or base, why? (LT 8E, 8F)

   b) What is the pH of a NaOH_{(aq)} solution with [H^+] = 3.1 \times 10^{-11} M? Name this substance. Is it an acid or base, why? (LT 8E, 8F)

10. A 15.0 mL sample of 0.250M HNO{3(aq)} is titrated to the end point with a 25.0 mL sample of KOH{(aq)}.

    a) Write a balanced equation including state symbols to represent the neutralization (double replacement) reaction. (LT 8F)

    b) Determine the molarity (M) of the KOH solution using the titration data provided. (LT 8F)

    Variables list: Formula / Plug-in with boxed answer:

    c) If the actual molarity of the KOH is 0.135 M, determine the percent error for this titration. (LT 8F)

    Variables list: Formula / Plug-in with boxed answer: