Exam 1 Practice

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Scientific Method, Properties, Classification of Matter

1. Classify each statement as being either qualitative or quantitative.

   1. This recitation worksheet took a good amount of time to complete
   2. This recitation worksheet took 50 minutes to complete
   3. The University of Georgia is a very large school

   Solution

   Answer:
   

   1. qualitative
      
   2. quantitative
      
   3. qualitative

   Concept: Classificying data

   
   

2. Which statement best explains the difference between a law and a theory?

   1. A law is truth whereas a theory is mere speculation.
   2. A law summarizes a series of related observations, while a theory gives the underlying reasons for them.
   3. A theory describes what nature does; a law explains why nature does it.

   Solution

   Answer: B

   Concept: Scientific method

   A law is the “what” and a theory is the “why”.

   
   

3. A scientific law…

   1. is a statement that summarizes past observations and makes predictions.
   2. is subject to change via legal action.
   3. contains an explanation of observations.
   4. must have a mathematical formula.
   5. cannot be modified.

   Solution

   Answer: A

   Concept: Scientific method

   A scientific law summarizes past observations and makes predictions about natural phenomena without explaining the underlying mechanisms.

   
   

4. All statements about scientific theories are true except

   1. they explain why nature behaves the way it does.
   2. they must have the ability to make predictions on future behavior.
   3. they should use observations to test the theory.
   4. they are derived from hypothesis.
   5. they are speculation.

   Solution

   Answer: E

   Concept: Scientific method

   Scientific theories are well-substantiated explanations of natural phenomena, based on a large body of evidence from repeated experiments and observations.

   
   

5. Which of these represents a hypothesis?

   1. Sodium reacts with water to form sodium hydroxide and hydrogen gas.
   2. Nitrogen gas is a fairly inert substance.
   3. Nickel has a silvery sheen.
   4. When a substance combusts, it combines with air.
   5. When wood burns, heat is given off.

   Solution

   Answer: D

   Concept: Scientific method

   D is a hypothesis because it is a tentative explanation that is testable and falsifiable.

   A is an observed chemical reaction and a statement of fact.
   B is a general property of nitrogen and a descriptive statement.
   C is a physical property of nickel and a statement of observation.
   E is a description of an observed phenomenon and not a testable explanation.

   
   

6. Which of the following is a homogeneous mixture?

   1. wine
   2. mud
   3. salad
   4. salsa

   Solution

   Answer: A

   Concept: Mixtures

   
   

7. Which of the following is a heterogeneous mixture?

   1. sports drink
   2. chlorine gas
   3. black coffee
   4. bowl of cereal
   5. carbon (graphite)

   Solution

   Answer: D

   Concept: Mixtures

   
   

8. Which of the following is not an example of a homogeneous mixture?

   1. air
   2. rain
   3. steel
   4. blood
   5. coffee

   Solution

   Answer: D

   Concept: Mixtures

   
   

9. Molecules can be described as

   1. mixtures of two or more pure substances
   2. mixtures of two or more elements that has a specific ratio between components
   3. two or more atoms chemically joined together
   4. heterogeneous mixtures
   5. homogeneous mixtures

   Solution

   Answer: C

   Concept: Classification of matter

   
   

10. Which of these separations cannot be achieved using a physical process and, therefore, requires a chemical process?

    1. salt from sea water
    2. water from honey
    3. hydrogen from water
    4. ice from water
    5. fish from water

    Solution

    Answer: C

    Concept: Separation of mixtures

    H₂O is a molecule and each hydrogen atom is chemically bonded to an oxygen atom.

    A, D, and E can be separated via filtration. B is separated via distillation.

    
    

11. All of the following will lead to a heterogeneous mixture except (select all that apply)

    1. sugar and coffee
    2. mud and water
    3. salt and water
    4. tea and no-pulp lemonade
    5. vinegar and water

    Solution

    Answer: A, C, D, E

    Concept: Mixtures

    
    

12. How are gases different from solids and liquids?

    1. Gases can only be made up of atoms
    2. Particles in a gas attract each other more strongly than in solids and liquids
    3. Gases are compressible
    4. Only gases can take the shape of their container
    5. Gases are colorless

    Solution

    Answer: C

    Concept: States of matter

    
    

13. Identify the incorrect statement.

    1. Helium in a balloon is an element
    2. Paint is a mixture
    3. Tap water is a compound
    4. Mercury in a barometer is an element

    Solution

    Answer: C

    Concept: Classification of matter

    Tap water is not a compound as it is a mixture/solution that contains many other dissolved particles such as O₂(g), Mg, Fe, Ca, etc. Pure water, H₂O(l), would be a compound.

    
    

14. Which answer includes all the following that are chemical changes and not physical changes?
     I. freezing of water
     II. rusting of iron
     III. dropping a piece of iron into hydrochloric acid where H₂(g) is produced
     IV. burning of a piece of wood
     V. emission of light by a kerosene oil lamp

    1. III and IV
    2. II and V
    3. I, II, III, IV, and V
    4. II, III, and V
    5. II, III, IV, and V

    Solution

    Answer: E

    Concept: chemical and physical changes

    
    

15. Which answer includes all of the following properties of sulfur that are physical properties and not other properties?
     I. It reacts with hydrogen when heated
     II. It is a yellow solid at room temperature
     III. It is soluble in carbon disulfide
     IV. It has a density of 2.97 g cm^–3
     V. It melts at 112 °C

    1. II, III, IV, and V
    2. II, IV, and V
    3. I
    4. II, III, and IV
    5. III, IV, and V

    Solution

    Answer: A

    Concept: chemical and physical properties

    
    

16. Which of the following is a chemical change?

    1. forging of metal
    2. boiling water
    3. shattering glass
    4. rust forming on a bike
    5. melting ice

    Solution

    Answer: D

    Concept: chemical changes

    
    

17. Which of the following would you expect to have the highest density?

    1. oxygen
    2. lead
    3. water
    4. helium

    Solution

    Answer: B

    Concept: chemical changes

    Oxygen and helium are gasses and water is a liquid at room temperature. States of matter with less order are more likely to be less dense (although not always)

    
    

Measurements, Derived Units, Significant Figures

1. A student is using a graduated cylinder to measure the volume of a liquid. What reading should be recorded?

   

   Solution

   Answer: 24.0 mL; the zero in the tenths-place is the uncertain (estimated) number

   Concept: uncertainty; measurement

   
   

2. A student performs an experiment to determine the density of a sugar solution. She obtains the following results: 1.11 g mL^–1, 1.81 g mL^–1, 1.95 g mL^–1, 1.75 g mL^–1. The actual value for the density of the sugar solution is 1.75 g mL^–1. Determine if the following statements are true or false.

   1. Her results are precise.
   2. Her results are accurate.

   Solution

   Answer: A and B are both false.

   Concept: Accuracy and precision

   
   

3. A student goes to the lab and is tasked with measuring the mass of a block of nickel metal that has a known mass of 15.00 g. The student takes three different measurements in which they collect the following masses: 13.29 g, 13.28 g, and 13.29 g. What statement best describes their results?

   1. Their measurements are both precise and accurate
   2. Their measurements are precise, but not accurate
   3. Their measurements are accurate, but not precise
   4. Their measurements are neither precise or accurate

   Solution

   Answer: B

   Concept: Accuracy and precision

   
   

4. Write the following numbers in normalized scientific notation to three significant figures.

   1. 0.000 467 01
   2. 8 973.002
   3. 0.027 902 0
   4. 32.451 3
   5. 0.000 090 999

   Solution

   Answer:
   

   1. 4.67 × 10^–4
      
   2. 8.97 × 10³
      
   3. 2.79 × 10^–2
      
   4. 3.25 × 10¹
      
   5. 9.10 × 10^–5

   Concept: Scientific notation

   
   

5. How many significant figures are in each number?

   1. 554 km
   2. 7 pennies
   3. 1.01 × 10⁵ m
   4. 0.00099 s
   5. 1.4500 km
   6. 21 000 m

   Solution

   Answer:
   

   1. 3
      
   2. ∞ (obtained via counting)
      
   3. 3
      
   4. 2
      
   5. 5 
   6. ambiguous but considered to be 2 for this class

   Concept: Significant figures

   
   

6. Determine the number of significant figures for each of the following values.

   1. 4 700
   2. 0.470 0
   3. 4 700 pencils
   4. 00.470 0
   5. 4 700.0 g
   6. 4 700.010 0

   Solution

   Answer:
   

   1. ambiguous but considered to be 2 for this class
      
   2. 4
      
   3. ∞ (obtained via counting)
      
   4. 4
      
   5. 5
   6. 8

   Concept: Significant figures

   
   

7. How many significant figures are in the answer to the following calculation?

   \[\left ( 29.0025 + 0.2 \right ) \left (6.134 - 6.101 \right ) / 5.196\times 10^{-2}\]

   Solution

   Answer: 2

   Concept: Significant figures

   \[\begin{align*} (29.0025 + 0.2)(6.134-6.101) / 5.196\times 10^{-2} &= \\ (29.\bar{2}02)(0.03\bar{3}0) / 5.196\times 10^{-2} &= \\ (0.9\bar{6}36) / 5.196\times 10^{-2} &= 1\bar{8}.546 \\ &= 19 \end{align*}\]

   
   

8. What answer should be reported, with the correct number of significant figures, for the following calculation? Report your answer in scientific notation.

   \[\left ( 433.621 - 333.9 \right ) \times 11.900\]

   Solution

   Answer: 1.19 × 10³

   Concept: Significant figures

   \[\begin{align*} \left ( 433.621 - 333.9 \right ) \times 11.900 &= \\[1.5ex] \left ( 99.\bar{7}21 \right ) \times 11.900 &= 11\bar{8}6.7 \\[1.5ex] &= 1,190 \\[1.5ex] &= 1.19\times 10^3 \end{align*}\]

   
   

9. Perform the following conversions below. Report your answers in normalized scientific notation to the appropriate number of significant figures.

   1. 145.21 kg to mg
   2. 0.490 nm to m
   3. 42.1 cm³ to L
   4. 1.73 × 10⁵ m³ to cm³

   Solution

   Answer:
   

   1. 1.4521 × 10⁸ mg
      
   2. 4.50 × 10^–10 m
      
   3. 4.21 × 10^–2 L
      
   4. 1.73 × 10¹¹ cm³

   Concept: Significant figures; scientific notation

   \[\begin{align*} \mathbf{A.}~ &145.21~\mathrm{kg} \left ( \dfrac{10^3~\mathrm{g}}{\mathrm{kg}} \right ) \left ( \dfrac{10^3~\mathrm{mg}}{\mathrm{g}} \right ) = 1.4521\times 10^{8}~\mathrm{mg} \\[1.5ex] \mathbf{B.}~ &0.490~\mathrm{nm} \left ( \dfrac{\mathrm{m}}{10^9~\mathrm{nm}} \right ) = 4.50\times 10^{-10}~\mathrm{m} \\[1.5ex] \mathbf{C.}~ &42.1~\mathrm{cm}^3 \left ( \dfrac{\mathrm{mL}}{\mathrm{cm}^3} \right ) \left ( \dfrac{\mathrm{L}}{10^3~\mathrm{mL}} \right ) = 4.21\times 10^{-2}~\mathrm{L}\\[1.5ex] \mathbf{D.}~ &1.73\times 10^5~\mathrm{m}^3 \left ( \dfrac{\mathrm{10^2~cm}}{\mathrm{m}} \right )^3 = 1.73\times 10^{11}~\mathrm{cm^3} \end{align*}\]

   
   

10. Which of the following options is at the highest temperature?

    1. 71.4 °F
    2. 22.1 °C
    3. 294.65 K

    Solution

    Answer: B

    Concept: Temperature

    This solution converts all temperatures to °C.

    \[\begin{align*} \textbf{A.}~~~ T\left ( ^{\circ}\mathrm{C} \right ) &= \dfrac{ [ T(^{\circ}\mathrm{F}) - 32 ]}{1.8} \\[1.5ex] &= \dfrac{ \left ( 71.4~^{\circ}\mathrm{F} - 32\right ) }{1.8} \\[1.5ex] &= 21.\bar{8}8~^{\circ}\mathrm{C} \\[1.5ex] &= 21.9~^{\circ}\mathrm{C}\\[6ex] \textbf{B.}~~~ T\left ( ^{\circ}\mathrm{C} \right ) &= 22.1~^{\circ}\mathrm{C} \\[6ex] \textbf{C.}~~~ T\left (^{\circ}\mathrm{C} \right ) &= T(\mathrm{K}) - 273.15 \\[1.5ex] &= 294.65~\mathrm{K} - 273.15 \\[1.5ex] &= 21.50~^{\circ}\mathrm{C} \end{align*}\]

    
    

11. The average daytime temperatures on Earth and Jupiter are 72 °F and 313 K, respectively. Which planet is hotter, on average, and by how much (in °C)?

    Solution

    Answer: Jupiter, 18 °C

    Concept: Temperature

    \[\begin{align*} T_{\mathrm{Earth}}\left ( ^{\circ}\mathrm{C} \right ) &= \dfrac{ [ T_{\mathrm{Earth}}(^{\circ}\mathrm{F}) - 32 ]}{1.8} \\[1.5ex] &= \dfrac{\left ( 72~^{\circ}\mathrm{F} - 32 \right )}{1.8} \\[1.5ex] &= 2\bar{2}.22~^{\circ}\mathrm{C}\\[6ex] T_{\mathrm{Jupiter}}\left (^{\circ}\mathrm{C} \right ) &= T_{\mathrm{Jupiter}}(\mathrm{K}) - 273.15 \\[1.5ex] &= 313~\mathrm{K} - 273.15 \\[1.5ex] &= 3\bar{9}.85~^{\circ}\mathrm{C} \\[6ex] \Delta T &= T_{\mathrm{Jupiter}}\left (^{\circ}\mathrm{C} \right ) - T_{\mathrm{Earth}}\left (^{\circ}\mathrm{C} \right ) \\[1.5ex] &= 3\bar{9}.85~^{\circ}\mathrm{C} - 2\bar{2}.22~^{\circ}\mathrm{C}\\[1.5ex] &= 1\bar{7}.63~^{\circ}\mathrm{C} \\[1.5ex] &= 18~^{\circ}\mathrm{C} \end{align*}\]

    
    

12. What is the length (in mm) of 3.20 cm?

    Solution

    Answer: 32.0 mm

    Concept: Metric conversions

    \[\begin{align*} 3.20~\mathrm{cm} \left ( \dfrac{\mathrm{m}}{10^2~\mathrm{cm}} \right ) \left ( \dfrac{10^3~\mathrm{mm}}{\mathrm{m}} \right ) = 32.0~\mathrm{mm} \end{align*}\]

    
    

13. If the walls in a room are 955 ft² in area, and a gallon of paint covers 15 yd², how many gallons of paint are needed for the room? (3 ft = 1 yd)

    Solution

    Answer: 7.1 gal

    Concept: Conversions

    \[\begin{align*} 955~\mathrm{ft^2} \left ( \dfrac{\mathrm{gal}}{15~\mathrm{yd^2}} \right ) &= 7.\bar{0}74~\mathrm{gal} \\[1.5ex] &= 7.1~\mathrm{gal} \end{align*}\]

    
    

14. A piece of metal ore has a mass of 9.25 g. When a student places it into a graduated cylinder containing water, the liquid level rises from 21.25 mL to 26.47 mL. What is the density (in g mL^–1) of the ore?

    Solution

    Answer: 1.77 g mL^–1

    Concept: Density; volume displacement

    \[\begin{align*} V(\mathrm{ore}) &= V_{\mathrm{f}} - V_{\mathrm{i}} \\[1.5ex] &= 26.47~\mathrm{mL} - 21.25~\mathrm{mL} \\[1.5ex] &= 5.22~\mathrm{mL}\\[3ex] d(\mathrm{ore}) &= \dfrac{m}{V} \\[1.5ex] &= \dfrac{9.25~\mathrm{g}}{5.22~\mathrm{mL}} \\[1.5ex] &= 1.7\bar{7}20~\mathrm{g~mL^{-1}}\\[1.5ex] &= 1.77~\mathrm{g~mL^{-1}} \end{align*}\]

    
    

15. A sample containing 33.42 g of metal pellets is poured into a graduated cylinder that initially contains 12.7 mL of water. The final water level in the cylinder is 21.6 mL. What is the density (in g mL^–1) of the metal?

    Solution

    Answer: 3.8 g mL^–1

    Concept: Density; volume displacement

    \[\begin{align*} \Delta V &= V_{\mathrm{final}} - V_{\mathrm{initial}} \\[1.5ex] &= 21.6~\mathrm{mL} - 12.7~\mathrm{mL} \\[1.5ex] &= 8.9~\mathrm{mL}\\[3ex] d &= \dfrac{m}{V} \\[1.5ex] &= \dfrac{33.42~\mathrm{g}}{8.9~\mathrm{mL}} \\[1.5ex] &= 3.\bar{7}55~\mathrm{g~mL^{-1}} = 3.8~\mathrm{g~mL^{-1}} \end{align*}\]

    
    

16. Nitric acid is a very important industrial chemical and 1.612 × 10¹⁰ lb were produced in 1992. If the density of nitric acid is 12.53 lb gal^–1, what is the volume (in L)? 1 gal = 3.7854 L

    Solution

    Answer: 4.870 × 10⁹ L

    Concept: Conversions

    \[\begin{align*} 1.612\times 10^{10}~\mathrm{lb} \left ( \dfrac{1~\mathrm{gal}}{12.53~\mathrm{lb}} \right ) \left ( \dfrac{3.7854~\mathrm{L}}{1~\mathrm{gal}} \right ) &= 4.86\bar{9}96\times 10^{9}~\mathrm{L} \\[1.5ex] &= 4.870\times 10^{9}~\mathrm{L} \end{align*}\]

    
    

17. A rectangular block has the following dimensions: 2.9 cm × 3.5 cm × 10.0 cm. The mass of the block is 615.0 g. What is the volume (in cm³) and density (in kg m^–3) of the block?

    Solution

    Answer: 1.0 × 10² cm³; 6.1& times; 10³ kg m^–3

    Concept: volume; density

    \[\begin{align*} V &= l \times w \times h \\[1.5ex] &= 2.9~\mathrm{cm} \times 3.5~\mathrm{cm} \times 10.0~\mathrm{cm} \\[1.5ex] &= 1\bar{0}1.5~\mathrm{cm^3} \\[1.5ex] &= 1.0\times 10^2~\mathrm{cm^3} \\[3ex] d &= \dfrac{m}{V} \\[1.5ex] &= \dfrac{615.0~\mathrm{g}}{1\bar{0}1.5~\mathrm{cm^3}} \left ( \dfrac{\mathrm{kg}}{10^3~\mathrm{g}} \right ) \left ( \dfrac{10^2~\mathrm{cm}}{\mathrm{m}} \right )^3 \\[1.5ex] &= 6\bar{0}59~\mathrm{kg~m^{-3}} = 6.1\times 10^{3}~\mathrm{kg~m^{-3}} \end{align*}\]

    
    

18. At room temperature, elemental bromine (Br₂) is a liquid with a density of 3.12 g cm^–3. What is the mass (in g) of 125 mL of bromine and what volume (in mL) does 85.0 g of bromine occupy?

    Solution

    Answer: 390. g; 27.2 mL

    Concept: volume; density

    \[\begin{align*} d &= \dfrac{m}{V} \longrightarrow \\[1.5ex] m &= Vd \\ &= 125~\mathrm{mL} \left ( \dfrac{3.12~\mathrm{g}}{\mathrm{cm}^3} \right ) \left ( \dfrac{\mathrm{cm}^3}{\mathrm{mL}} \right ) \\[1.5ex] &= 390.~\mathrm{g}\\[3ex] d &= \dfrac{m}{V} \longrightarrow \\[1.5ex] V &= \dfrac{m}{d} \\[1.5ex] &= \dfrac{85.0~\mathrm{g}}{3.12~\mathrm{g~cm^{-3}}} \left ( \dfrac{\mathrm{mL}}{\mathrm{cm}^3} \right ) \\[1.5ex] &= 27.\bar{2}43~\mathrm{mL} \\[1.5ex] &= 27.2~\mathrm{mL} \end{align*}\]

    
    

19. The Hindenburg contained 7.062 × 10⁶ ft³ of a gas. If the gas was helium ( d(He) = 1.78 × 10^–4 g mL^–1 ), how much lighter (in kg) would it be than if the gas was air (d(air) = 1.293 × 10^–3 g mL^–1)? (1 ft = 0.3048 m)

    Solution

    Answer: 2.23 × 10⁵ kg

    Concept: volume; density

    \[\begin{align*} V &= 7.062\times 10^{6}~\mathrm{ft}^3 \left ( \dfrac{0.3048~\mathrm{m}}{\mathrm{ft}} \right )^3 \left ( \dfrac{10^2~\mathrm{cm}}{\mathrm{m}} \right )^3 \left ( \dfrac{\mathrm{mL}}{\mathrm{cm^3}} \right ) \\[1.5ex] &= 2.000\times 10^{11}~\mathrm{mL}\\[3.0ex] d &= \dfrac{m}{V} \longrightarrow \\[1.5ex] m(\textrm{He}) &= Vd(\textrm{He}) \\[1.5ex] &= 2.000\times 10^{11}~\mathrm{mL} \left ( \dfrac{1.78\times 10^{-4}~\mathrm{g}}{\mathrm{mL}} \right ) \left ( \dfrac{\mathrm{kg}}{10^3~\mathrm{g}} \right ) \\[1.5ex] &= 3.5\bar{6}0\times 10^{4}~\mathrm{kg}\\[3ex] m(\textrm{air}) &= Vd(\textrm{air}) \\[1.5ex] &= 2.000\times 10^{11}~\mathrm{mL} \left ( \dfrac{1.293\times 10^{-3}~\mathrm{g}}{\mathrm{mL}} \right ) \left ( \dfrac{\mathrm{kg}}{10^3~\mathrm{g}} \right ) \\[1.5ex] &= 2.58\bar{6}0\times 10^{5}~\mathrm{kg}\\[3ex] \Delta m &= m(\textrm{air}) - m(\textrm{He}) \\[1.5ex] &= 2.58\bar{6}0\times 10^{5}~\mathrm{kg} - 3.56\times 10^{4}~\mathrm{kg} \\[1.5ex] &= 25.8\bar{6}0\times 10^{4}~\mathrm{kg} - 3.56\times 10^{4}~\mathrm{kg} \\[1.5ex] &= (25.8\bar{6}0 - 3.56) \times 10^4 \\[1.5ex] &= 22.30\times 10^4~\mathrm{kg} \\[1.5ex] &= 2.23\times 10^{5}~\mathrm{kg} \end{align*}\]

    
    

Atoms, Atomic Theory, Periodic Table

1. An unused flashbulb contains magnesium and oxygen. After use, the contents are changed to magnesium oxide but the total mass does not change. This observation can best be explained by the…

   1. Law of Constant Composition
   2. Law of Multiple Proportions
   3. Avogadro’s Law
   4. Law of Conservation of Mass

   Solution

   Answer: D

   Concept: Laws

   
   

2. Which of the statements about two isotopes is false?

   1. They will have the same charge on the nucleus.
   2. They will have different numbers of neutrons.
   3. They will have essentially the same chemical reactivity.
   4. They will have the same atomic numbers.
   5. They will have the same atomic weights.

   Solution

   Answer: E

   Concept: atomic structure; isotopes

   
   

3. What is the mass number for ²⁵Mg?

   Solution

   Answer: 25

   Concept: atomic structure; isotopes

   
   

4. Which of the following represents isotopes?
    I. \(^{46}_{21}X\)
    II. \(^{46}_{22}X\)
    III. \(^{46}_{21}X\)
    IV. \(^{46}_{23}X\)

   1. I and II
   2. I and III
   3. I and IV
   4. III and IV

   Solution

   Answer: B

   Concept: atomic structure; isotopes

   Isotopes of a given element vary in mass number have the same atomic number.

   
   

5. Complete the table.

   
   

   Solution

   Answer: B

   Concept: atomic structure; isotopes

   
   

6. Write the group number for each of the following elements.

   1. Ba
   2. Sb
   3. Zr
   4. Tl
   5. Rn

   Solution

   Answer:
   

   1. group 2 (or 2A)
      
   2. group 15 (or 5A)
      
   3. group 4 (or 4B)
      
   4. group 13 (or 3A)
      
   5. group 18 (or 8A)
      

   Concept: periodic table

   
   

7. Write the period number for each of the following elements.

   1. Hf
   2. Am
   3. Ga
   4. Si
   5. He

   Solution

   Answer:
   

   1. 6
      
   2. 7
      
   3. 4
      
   4. 3
      
   5. 1
      

   Concept: periodic table

   
   

8. Which of the following elements is a metal?

   1. Ge
   2. Sb
   3. H
   4. Sn
   5. Cl

   Solution

   Answer: D

   Concept: periodic table

   
   

9. Which of the following elements is a nonmetal?

   1. Ca
   2. Si
   3. Mo
   4. Cs
   5. Se

   Solution

   Answer: E

   Concept: periodic table

   
   

10. What quantity did J. J. Thompson determine using a cathode ray tube?

    1. the mass of an electron
    2. the charge-to-mass ratio of an electron
    3. the density of a proton
    4. the charge of a neutron
    5. the charge-to-mass ratio of a proton

    Solution

    Answer: B

    Concept: famous experiments

    
    

11. Which of the following is found in the nucleus?

    1. cations
    2. neutrons
    3. electrons
    4. anions
    5. none of these

    Solution

    Answer: B

    Concept: atomic structure

    
    

12. Which of these is not found in an atom?

    1. electron
    2. neutron
    3. photon
    4. proton
    5. all of them are

    Solution

    Answer: C

    Concept: atomic structure

    
    

13. True or False: an atom consists mostly of empty space.

    1. true
    2. false, an atom consists primarly of electrons
    3. false, an atom consists primarily of the nucleus
    4. false, an atom consists primarly of neutrons
    5. false, an atom consists primarly of protons

    Solution

    Answer: A

    Concept: atomic structure

    
    

14. Which of the following contribute to the mass of an atom? (select all that apply)

    1. protons
    2. neutrons
    3. electrons
    4. electrons
    5. the nucleus
    6. atomic charge

    Solution

    Answer: A and B

    Concept: atomic structure

    
    

15. An element consists of four naturally occurring isotopes. The percent abundance and isotope masses are given as:

    1. 1.40 %; 203.973 u
    2. 24.10 %; 205.9754 u
    3. 22.10 %; 206.9759 u
    4. 52.40 %; 207.9766 u

    Find the standard atomic weight (in u) of the element

    Solution

    Answer: 207.2 u

    Concept: percent abundance; isotopes

    \[\begin{align*} A_{\mathrm{r}}^{\circ}(E) &= \left ( \dfrac{x \! \left ( X_1 \right )\%}{100~\%} \right ) \left [ A_{\mathrm{r}} \! \left ( X_1 \right ) \right ] + \left ( \dfrac{x \! \left ( X_2 \right )\%}{100~\%} \right ) \left [ A_{\mathrm{r}} \! \left ( X_2 \right ) \right ] + \\ &\phantom{=}~\, \left ( \dfrac{x \! \left ( X_3 \right )\%}{100~\%} \right ) \left [ A_{\mathrm{r}} \! \left ( X_3 \right ) \right ] + \left ( \dfrac{x \! \left ( X_4 \right )\%}{100~\%} \right ) \left [ A_{\mathrm{r}} \! \left ( X_4 \right ) \right ] \\[2ex] A_{\mathrm{r}}^{\circ}(\mathrm{B}) &= \left ( \dfrac{1.40~\%}{100~\%} \right ) \left ( 203.973~\mathrm{u} \right ) + \left ( \dfrac{24.10~\%}{100~\%} \right ) \left ( 205.9754~\mathrm{u} \right ) + \\ &\phantom{=}~\, \left ( \dfrac{22.10~\%}{100~\%} \right ) \left ( 206.9759~\mathrm{u} \right ) + \left ( \dfrac{52.40~\%}{100~\%} \right ) \left ( 207.9766~\mathrm{u} \right ) \\[2ex] &= 20\bar{7}.21~\mathrm{u} \\[0.5ex] &= 207~\mathrm{u} \end{align*}\]

    
    

16. The element rhenium (Re) has a standard atomic weight of 186.207 and exists as two naturally occurring isotopes. Given the following percent abundance and isotope mass

    1. ¹⁸⁵Re
    2. ¹⁸⁷Re: 62.60 %; 186.956

    find the relative atomic weight of rhenium-185.

    Solution

    Answer: 185

    Concept: percent abundance; isotopes

    \[\begin{align*} A_{\mathrm{r}}^{\circ} \left ( \mathrm{Re} \right ) &= x \left (\mathrm{^{185}Re} \right ) ~ A_{\mathrm{r}} \left ( \mathrm{^{185}Re} \right ) + x \left (\mathrm{^{187}Re} \right ) ~ A_{\mathrm{r}} \left ( \mathrm{^{187}Re} \right ) \longrightarrow \\[1.5ex] A_{\mathrm{r}} \left ( \mathrm{^{185}Re} \right ) &= \dfrac{ A_{\mathrm{r}}^{\circ} \left ( \mathrm{Re} \right ) - \Biggr [ x \left (\mathrm{^{187}Re} \right ) ~ A_{\mathrm{r}} \left ( \mathrm{^{187}Re} \right ) \Biggr] } {x \left (\mathrm{^{185}Re} \right )}\\[0.5ex] &= \dfrac{ 186.207 - \Biggr[ \left ( \dfrac{62.60~\%}{100~\%} \right ) \left ( 186.956 \right ) \Biggr] } { \dfrac{\left ( 100~\%-62.60~\%\right ) }{100~\%} }\\[0.5ex] &= 184.\bar{9}53 \\[0.5ex] &= 185 \end{align*}\]

    
    

Ions, Ionic Compounds, Molecules, and Nomenclature

1. What is the correct charge of a sulfur atom with 16 protons, 16 neutrons, and 18 electrons?

   Solution

   Answer: 2–

   Concept: atomic structure; ions

   
   

2. What charge will most likely be formed by lithium?

   Solution

   Answer: 1+

   Concept: ions

   
   

3. Is iodine more likely to gain or lose an electron?

   Solution

   Answer: Gain an electron (to increase its stability)

   Concept: ions

   
   

4. What is the atomic mass (in amu) of a magnesium ion containing 12 protons, 13 neutrons, and 10 electrons?

   Solution

   Answer: 25 amu

   Concept: isotopes

   
   

5. Fill out the missing information regarding a binary ionic compound.

   1. Name: sodium chloride
   2. Cation:
   3. Anion:
   4. Formula:

   Solution

   Answer:
   

   1. Name: sodium chloride
      
   2. Cation: Na⁺
      
   3. Anion: Cl⁻
      
   4. Formula: NaCl

   Concept: ionic compounds

   
   

6. Fill out the missing information regarding a binary ionic compound.

   1. Name:
   2. Cation: Mg²⁺
   3. Anion: O^2–
   4. Formula:

   Solution

   Answer:
   

   1. Name: magnesium oxide
      
   2. Cation: Mg²⁺
      
   3. Anion: O^2–
      
   4. Formula: MgO

   Concept: ionic compounds

   
   

7. Fill out the missing information regarding a binary ionic compound.

   1. Name:
   2. Cation:
   3. Anion:
   4. Formula: Al₂S₃

   Solution

   Answer:
   

   1. Name: aluminum sulfide
      
   2. Cation: Al³⁺
      
   3. Anion: S^2–
      
   4. Formula: Al₂S₃

   Concept: ionic compounds

   
   

8. Fill out the missing information regarding a binary ionic compound.

   1. Name: iron(III) oxide
   2. Cation:
   3. Anion:
   4. Formula:

   Solution

   Answer:
   

   1. Name: iron(III) oxide
      
   2. Cation: Fe³⁺
      
   3. Anion: O^2–
      
   4. Formula: Fe₂O₃

   Concept: ionic compounds

   
   

9. Fill out the missing information regarding a binary ionic compound.

   1. Name:
   2. Cation: Sn²⁺
   3. Anion: Cl^–
   4. Formula:

   Solution

   Answer:
   

   1. Name: tin(II) chloride
      
   2. Cation: Sn²⁺
      
   3. Anion: Cl^–
      
   4. Formula: SnCl₂

   Concept: ionic compounds

   
   

10. Fill out the missing information regarding a binary ionic compound.

    1. Name:
    2. Cation:
    3. Anion:
    4. Formula: PbF₄

    Solution

    Answer:
    

    1. Name: lead(IV) fluoride
       
    2. Cation: Pb⁴⁺
       
    3. Anion: F^–
       
    4. Formula: PbF₄

    Concept: ionic compounds

    
    

11. Fill out the missing information regarding a binary ionic compound.

    1. Name: sodium hydroxide
    2. Cation:
    3. Anion:
    4. Formula:

    Solution

    Answer:
    

    1. Name: sodium hydroxide
       
    2. Cation: Na⁺
       
    3. Anion: OH^–
       
    4. Formula: NaOH

    Concept: ionic compounds

    
    

12. Fill out the missing information regarding a binary ionic compound.

    1. Name:
    2. Cation: Mg²⁺
    3. Anion: CO₃^2–
    4. Formula:

    Solution

    Answer:
    

    1. Name: magnesium carbonate
       
    2. Cation: Mg²⁺
       
    3. Anion: CO₃^2–
       
    4. Formula: MgCO₃

    Concept: ionic compounds

    
    

13. Fill out the missing information regarding a binary ionic compound.

    1. Name:
    2. Cation:
    3. Anion:
    4. Formula: Na₂SO₃

    Solution

    Answer:
    

    1. Name: sodium sulfite
       
    2. Cation: Na⁺
       
    3. Anion: SO₃^2–
       
    4. Formula: Na₂SO₃

    Concept: ionic compounds

    
    

14. Fill out the missing information regarding a binary ionic compound.

    1. Name:
    2. Cation: Fe²⁺
    3. Anion: OH^–
    4. Formula:

    Solution

    Answer:
    

    1. Name: iron(II) hydroxide
       
    2. Cation: Fe²⁺
       
    3. Anion: OH^–
       
    4. Formula: Fe(OH)₂

    Concept: ionic compounds

    
    

15. Fill out the missing information regarding a binary ionic compound.

    1. Name:
    2. Cation:
    3. Anion:
    4. Formula: TiPO₃

    Solution

    Answer:
    

    1. Name: titanium(III) phosphate
       
    2. Cation: Ti³⁺
       
    3. Anion: PO₃^3–
       
    4. Formula: TiPO₃

    Concept: ionic compounds

    
    

16. Provide the names for the following compounds

    1. N₂O
    2. P₂O₅
    3. SF₂
    4. S₂O
    5. P₂I₄

    Solution

    Answer:
    

    1. dinitrogen monoxide
       
    2. diphosphorous pentoxide
       
    3. sulfur difluoride
       
    4. disulfur monoxide
       
    5. diphosphorous tetraiodide

    Concept: ionic compounds

    
    

17. What is the proper chemical formula for lithium hypoiodite?

    1. LiIO
    2. LiO₂
    3. LiIO₃
    4. LiIO₃
    5. LiIO₄

    Solution

    Answer: A

    Concept: ionic compounds

    
    

18. Write the chemical formula for a compound formed between aluminum and sulfur.

    Solution

    Answer: Al₂S₃

    Concept: ionic compounds

    
    

19. In which set do all elements tend to form cations in binary ionic compounds?

    1. Na, Al, S
    2. Ca, Mn, Sn
    3. P, As, Sb
    4. S, Cl, Br

    Solution

    Answer: B

    Concept: ions

    
    

20. Which of the following contains both ionic and covalent bonds?

    1. CaBr₂
    2. COS
    3. BaSO₄
    4. SF₆
    5. none of these

    Solution

    Answer: C

    Concept: ionic compounds

    
    

21. What is the name of the C₃H₈?

    1. hexane
    2. propane
    3. decane
    4. butane
    5. ethane

    Solution

    Answer: B

    Concept: nomenclature; organic molecule

    
    

22. What is the name of this compound?

    

    Solution

    Answer: octanol

    Concept: nomenclature; organic molecule

    
    

23. What is the chemical formula for magnesium carbide?

    Solution

    Answer: Mg₂C₃

    Concept: nomenclature

    
    

24. What is the name of PH₃?

    Solution

    Answer: phosphine

    Concept: nomenclature

    
    

25. Write the empirical formulas for the following compounds

    1. iron(II) sulfide
    2. iron(III) sulfide
    3. iron(II) sulfate
    4. iron(III) sulfate
    5. iron (II) sulfite

    Solution

    Answer:
    

    1. FeS
    2. Fe₂S₃
    3. FeSO₄
    4. Fe₂(SO₄)₃
    5. FeSO₃

    Concept: nomenclature

    
    

26. Provide the name for each of the following and identify it as a molecular or ionic compound

    
    

    Solution

    Answer: B

    Concept: nomenclature

    
    

27. Provide the name for each of the following and identify it as a molecular or ionic compound

    
    

    Solution

    Answer: B

    Concept: nomenclature

    
    

28. Provide the name for each of the following and identify it as an alkane, alcohol, or carboxylic acid.

    
    

    Solution

    Answer: B

    Concept: nomenclature

    
    

29. Provide the chemical formulas and identify each as molecular or ionic compound. Include phase labels where necessary.

    
    

    Solution

    Answer: B

    Concept: nomenclature

    
    

30. Provide the chemical formulas and identify each as molecular or ionic compound. Include phase labels where necessary.

    
    

    Solution

    Answer: B

    Concept: nomenclature

    
    

Questions are written by UGA Chemistry unless otherwise indicated and translated with minor tweaks into an online format by Eric Van Dornshuld.