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    Chemistry worksheet
    Topic: Electrolyte

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    Electrolyte
    1

    Which compounds are electrolytes?

    (1) C2H5OH and H2SO4

    (2) C2H5OH and CH4

    (3) KOH and H2SO4

    (4) KOH and CH4

    2

    Which substance is an electrolyte?

    (1) C6H12O6(s)

    (2) C2H5OH(ℓ)

    (3) NaOH(s)

    (4) H2(g)

    3

    Which two compounds are electrolytes?

    (1) KOH and CH3COOH

    (2) KOH and C5H12

    (3) CH3OH and CH3COOH

    (4) CH3OH and C5H12

    4

    The electrical conductivity of an aqueous solution depends on the concentration of which particles in the solution?

    (1) molecules

    (2) electrons

    (3) atoms

    (4) ions

    5

    Why is potassium nitrate classified as an electrolyte?

    (1) It is a molecular compound.

    (2) It contains a metal.

    (3) It can conduct electricity as a solid.

    (4) It releases ions in an aqueous solution.

    6

    Which statement describes an electrolyte?

    (1) An electrolyte conducts an electric current as a solid and dissolves in water.

    (2) An electrolyte conducts an electric current as a solid and does not dissolve in water.

    (3) When an electrolyte dissolves in water, the resulting solution conducts an electric current.

    (4) When an electrolyte dissolves in water, the resulting solution does not conduct an electric current.

    7

    Which compound is an electrolyte?

    (1) CCl4

    (2) CH3OH

    (3) C6H12O6

    (4) Ca(OH)2

    8

    Which compound is an electrolyte?

    (1) CH3CHO

    (2) CH3OCH3

    (3) CH3COOH

    (4) CH3CH2CH3

    9

    Which compounds are classified as electrolytes?

    (1) KNO3 and H2SO4

    (2) KNO3 and CH3OH

    (3) CH3OCH3 and H2SO4

    (4) CH3OCH3 and CH3OH

    Base your answers to questions 10 on the information below.

    Ammonium chloride is dissolved in water to form a 0.10 M NH4Cl(aq) solution. This dissolving process is represented by the equation below.

    physical-behavior-of-matter, concentration-of-a-solution fig: chem12013-exam_g18.png

    10

    Explain, in terms of ions, why a 10.0-milliliter sample of 0.30 M NH4Cl(aq) is a better conductor of electricity than a 10.0-milliliter sample of the 0.10 M NH4Cl(aq).

    Allow 1 credit. Acceptable responses include, but are not limited to:

    • The 0.30 M NH4Cl(aq) sample has more mobile ions in solution.

    • The 0.10 M NH4Cl solution has a lower concentration of ions.

    Base your answers to questions 11 on the information below and on your knowledge of chemistry.

    A laboratory technician is given the table below and a sample of one of the three substances listed in the table. The technician makes an aqueous solution with a portion of the sample. When a conductivity tester is lowered into the solution, the lightbulb on the tester glows brightly. Another portion of the sample is placed in a heat-resistant container that is placed in an oven at 450.°C. The sample melts.

    chemical-bonding, differentiation-of-types-of-substances fig: chem12016-exam_g9.png

    11

    Explain, in terms of ions, why an aqueous solution of potassium chromate conducts an electric current.

    Allow 1 credit. Acceptable responses include, but are not limited to:

    • An aqueous solution of potassium chromate has mobile ions that conduct electricity.

    • The K2CrO4 dissociated into mobile ions.

    • Aqueous potassium chromate has charged particles that can move.

    • The K+(aq) and CrO42−(aq) move freely.

    Base your answers to questions 12 on the information below.

    Calcium reacts with water. This reaction is represented by the balanced equation below. The aqueous product of this reaction can be heated to evaporate the water, leaving a white solid, Ca(OH)2(s).

    Ca(s) + 2H2O(ℓ) → Ca(OH)2(aq) + H2(g)

    12

    Compare the electrical conductivity of the aqueous product in the reaction to the electrical conductivity of the white solid that remains after the water is evaporated from the solution.

    Allow 1 credit. Acceptable responses include, but are not limited to:

    • The solution can conduct an electric current better than the white solid.

    • The Ca(OH)2(aq) is a good conductor and Ca(OH)2(s) is not.

    Base your answers to questions 13 on the information below and on your knowledge of chemistry.

    A small digital clock can be powered by a battery made from two potatoes and some household materials. The “potato clock” battery consists of two cells connected in a way to produce enough electricity to allow the clock to operate. In each cell, zinc atoms react to form zinc ions. Hydrogen ions from phosphoric acid in the potatoes react to form hydrogen gas. The labeled diagram and balanced ionic equation below show the reaction, the materials, and connections necessary to make a “potato clock” battery.

    oxidation-reduction, oxidation-reduction-(redox)-reaction, oxidation-reduction, electrochemical-cell, voltaic-cell fig: chem62015-exam_g16.png

    13

    Explain why phosphoric acid is needed for the battery to operate.

    Allow 1 credit. Acceptable responses include, but are not limited to:

    • The H+ ions that are reduced come from the phosphoric acid.

    • Phosphoric acid releases ions that are free to move.

    • H3PO4 is an electrolyte.

    • H3PO4(aq) can act as a salt bridge.

    Base your answers to questions 14 on the information below and on your knowledge of chemistry.

    Vinegar is a commercial form of acetic acid, HC2H3O2(aq). One sample of vinegar has a pH value of 2.4.

    14

    Explain, in terms of particles, why HC2H3O2(aq) can conduct an electric current.

    Allow 1 credit. Acceptable responses include, but are not limited to:

    • The HC2H3O2(aq) has ions in water, which are mobile.

    • The charged particles move freely.

    • Acetic acid forms moveable ions in aqueous solution.

    Base your answers to questions 15 on the information below and on your knowledge of chemistry.

    In a laboratory investigation, an HCl(aq) solution with a pH value of 2 is used to determine the molarity of a KOH(aq) solution. A 7.5-milliliter sample of the KOH(aq) is exactly neutralized by 15.0 milliliters of the 0.010 M HCl(aq). During this laboratory activity, appropriate safety equipment is used and safety procedures are followed.

    15

    Explain, in terms of aqueous ions, why 15.0 mL of a 1.0 M HCl(aq) solution is a better conductor of electricity than 15.0 mL of a 0.010 M HCl(aq) solution.

    Allow 1 credit. Acceptable responses include, but are not limited to:

    • The 1.0 M solution has a greater concentration of mobile ions than the 0.010 M solution.

    • The 0.010 M solution has fewer mobile ions.

    • The 1.0 M solution has more aqueous ions.