NY Regents Chemistry Exam Jan 2023
When a voltmeter is connected in the circuit of a voltaic cell, an electrical measurement called voltage can be read on the meter. The voltage of the cell is affected if the concentration of the solute in the half-cells is changed. The diagram, the ionic equation, and the graph below represent a copper-zinc cell. When the switch is closed, electricity flows through the circuit as the cell operates at constant temperature.
80 Based on the graph, determine the voltage of the cell if the Cu(NO3)2(aq) concentration is 1.5 M. [1]
We need to find 1.5M on the x axis of the graph and then go up until we reach the line. The voltage is on the y-axis and should be around 1.105M
Answer: Any value from 1.102 V to 1.108 V, inclusive.
81 Write a balanced half-reaction equation for the oxidation of zinc that occurs in this operating cell. [1]
In the equation above, we see that Zn(s) turns into Zn2+(aq). Oxidation is loss of electrons and we should put 2 electrons on the right side.
Answer: Zn(s) → Zn2+(aq) + 2e-