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When a voltaic cell operates, ions move through the*
Based on Reference Table J, which two reactants react spontaneously?*
In an oxidation-reduction reaction, the total number of electrons lost is*
Which metal will spontaneously react with Zn2+(aq), but will not spontaneously react with Mg2+(aq)?*
Given the incomplete equation representing a reaction:
What is the formula of the missing product?*
In an oxidation-reduction reaction, the number of electrons lost is*
Which element reacts spontaneously with 1.0 M HCl(aq) at room temperature?*
Given the balanced ionic equation:
3Pb2+(aq) + 2Cr(s) → 3Pb(s) + 2Cr3+(aq)
What is the number of moles of electrons gained by 3.0 moles of lead ions?*
Given the balanced equation representing a reaction:
2Al(s) + 3Cu2+(aq) → 2Al3+(aq) + 3Cu(s)
Which particles are transferred in this reaction?*
Base your answers to questions 10 on the information below.
The diagram below represents an operating electrolytic cell used to plate silver onto a nickel key. As the cell operates, oxidation occurs at the silver electrode and the mass of the silver electrode decreases.
Explain, in terms of Ag atoms and Ag+(aq) ions, why the mass of the silver electrode decreases as the cell operates.*
Base your answers to questions 11 on the information below.
Metallic elements are obtained from their ores by reduction. Some metals, such as zinc, lead, iron, and copper, can be obtained by heating their oxides with carbon.
More active metals, such as aluminum, magnesium, and sodium, can not be reduced by carbon. These metals can be obtained by the electrolysis of their molten (melted) ores. The diagram below represents an incomplete cell for the electrolysis of molten NaCl. The equation below represents the reaction that occurs when the completed cell operates.
Identify one metal from the passage that is more active than carbon and one metal from the passage that is less active than carbon.*
Base your answers to questions 12 on the information below and on your knowledge of chemistry.
Fossil fuels produce air pollution and may eventually be depleted. Scientists are researching ways to use hydrogen as an alternate fuel.
A device called an artificial leaf was invented to produce hydrogen and oxygen using sunlight and water. The artifical leaf is an electrochemical cell. Equations 1 and 2 below represent the reactions taking place in the leaf. Equation 3 represents a reaction of hydrogen when used as fuel.
Equation 1: 2H2O + energy from sunlight → O2 + 4H+ + 4e−
Equation 2: 4H+ + 4e− → 2H2
Equation 3: 2H2(g) + O2(g) → 2H2O(g) + energy
State one benefit of using the artificial leaf to produce hydrogen.*
Base your answers to questions 13 on the information below and on your knowledge of chemistry.
The diagram and balanced ionic equation below represent two half-cells connected to produce an operating voltaic cell in a laboratory investigation. The half-cells are connected by a salt bridge.
State the purpose of the salt bridge in this voltaic cell.*
Base your answers to questions 14 on the information below and on your knowledge of chemistry.
A student sets up a voltaic cell using magnesium and zinc electrodes. The porous barrier in the cell has the same purpose as a salt bridge. The diagram and the ionic equation below represent this operating cell.
State, in terms of ions, how the porous barrier functions as a salt bridge in this cell.*
Base your answers to questions 15 on the information below.
A student constructs an electrochemical cell during a laboratory investigation. When the switch is closed, electrons flow through the external circuit. The diagram and equation below represent this cell and the reaction that occurs.
State the direction of electron flow through the wire when the switch is closed.*
