Which of the following reactions can occur in a voltaic cell with the generation of electron flow?
a) zn2+ + s2- → zns
b) zncl2 + h2s→ zns + 2hcl
c) zn+ cucl2 → zncl2 + cu
d) fe3+ + po43- → fepo4
e) none of above

c) Zn + CuCl₂ ⇒ ZnCl₂ + Cu

Explanation:

Voltaic cells are devices that take advantage of reactions of oxidation and reduction to generate electrical energy.

In the oxidation, a substance loses electrons and increases its oxidation state. This reaction occurs in an electrode known as anode.

In the reduction, a substance gains electrons and decreases its oxidation state. This reaction occurs in an electrode known as cathode.

Oxidation and reduction happen simultaneously and the flow of electrons from anode to cathode is what generates an electric potential.

From the reactions in the list, "c" is the only one where oxidation and reduction are present.

 Zn oxidizes into Zn²⁺ according to the reaction:

 Zn(s) ⇒ Zn²⁺(aq) + 2 e⁻

 The oxidation state increases from 0 to 2.

 Cu²⁺ reduces to Cu according to the reaction:

 Cu²⁺(aq) + 2 e⁻ ⇒ Cu(s)

 The oxidation state decreases from 2 to 0.

they both have a y in them

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.