Which of the following reactions does not involve oxidation-reduction?
a). C3H8 + 5O2 → 4H2O + 3CO2
b). Mg + 2HI → MgI2 + H2
c). Ba + 2H2O → Ba(OH)2 + H2
d). MnO2 + 4HI → I2 + 2H2O + MnI2
e). NaOH + HI → H2O + NaI
To determine which of the given reactions does not involve oxidation-reduction, we need to examine each reaction and identify any changes in oxidation numbers.
Oxidation is the loss of electrons, while reduction is the gain of electrons. If there is a change in oxidation numbers between reactants and products, it indicates an oxidation-reduction reaction. On the other hand, if there is no change in oxidation numbers, it suggests a reaction that does not involve oxidation-reduction.
Let's examine each reaction:
a) C3H8 + 5O2 → 4H2O + 3CO2
In this reaction, carbon in C3H8 loses four electrons and gains four oxygen atoms to form CO2. Oxygen in O2 gains four electrons and combines with carbon to form CO2. Since there is a change in oxidation numbers, this is an oxidation-reduction reaction.
b) Mg + 2HI → MgI2 + H2
In this reaction, magnesium (Mg) loses two electrons to form MgI2, and iodine in HI gains two electrons to form MgI2. There is a change in oxidation numbers, indicating an oxidation-reduction reaction.
c) Ba + 2H2O → Ba(OH)2 + H2
In this reaction, barium (Ba) reacts with water to form barium hydroxide (Ba(OH)2) and hydrogen gas (H2). There is no change in oxidation numbers for any of the elements. Therefore, this reaction does not involve oxidation-reduction.
d) MnO2 + 4HI → I2 + 2H2O + MnI2
In this reaction, manganese (Mn) in MnO2 loses electrons to form MnI2. Iodine in HI gains electrons to form I2. There is a change in oxidation numbers, indicating an oxidation-reduction reaction.
e) NaOH + HI → H2O + NaI
In this reaction, there is no change in oxidation numbers for any of the elements involved. Therefore, this reaction does not involve oxidation-reduction.
So, the reaction that does not involve oxidation-reduction is option c) Ba + 2H2O → Ba(OH)2 + H2.
The reaction that does not involve oxidation-reduction is the one in option e): NaOH + HI → H2O + NaI.
The point of this you missed. You should be able to look at them and see which ones changed oxidation state.
c for example, Ba is zero, goes to +2
d for example, Mn goes from +4 to +2
One of the equations oxdation states do not change.