Q4.96 P - Chemistry: Molecular Nature Of Matter And Change

Question

Predict the product(s) and write a balanced equation for each of the following redox reactions:

(a) Pentane (C₅H₁₂) + Oxygen →

(b) Phosphorus trichloride + Chlorine →

(c) Zinc + Hydrobromic acid →

(d) Aqueous Potassium iodide + Bromine →

(e) Write a balanced net ionic equation for (d).

Step-by-Step Solution

Answer

The product and the balance equation of the given reactions are:$$\begin{gathered} \left(a\right) C_5{H}_{12}\left(I\right)+8O_2\left(g\right)\to 5C{O}_2\left(g\right)+6H_{2}O\left(I\right) \\ \left(b\right) P{C}_3\left(I\right)+C{I}_2\left(g\right)\to PC{I}_5\left(s\right) \\ \left(c\right) Zn\left(s\right)+2HBr\left(aq\right)\to ZnB{r}_{}\left(aq\right)+H_2\left(g\right) \\ \left(d\right) 2KI\left(aq\right)+B{r}_2\left(I\right)\to 2KBr\left(aq\right)+I_2\left(s\right) \\ \left(e\right) 2I^{-}\left(aq\right)+B{r}_2\left(I\right)\to 2B{r}^{-}\left(aq\right)+I_2\left(s\right) \end{gathered}$$

Step 1: Determine the product of the equation (a)

The given redox reaction is a combustion reaction.

Combustion of pentane takes place in presence of oxygen and forms carbon dioxide and water.

Step 2: Write balanced chemical reaction of equation (a)

The balanced reaction is:

$C_5{H}_{12}\left(I\right)+8O_2\left(g\right)\to 5C{O}_2\left(g\right)+6H_{2}O\left(I\right)$

Step 3: Determine the product of the equation (b)

The given redox reaction is a combination reaction.

Phosphorous trichloride combines with chlorine and forms phosphorous pentachloride.

Step 4: Write balanced chemical reaction of equation (b)

The balanced reaction is:

$P{C}_3\left(I\right)+C{I}_2\left(g\right)\to PC{I}_5\left(s\right)$

Step 5: Determine the product of the equation (c)

The given redox reaction is a displacement reaction.

Zinc displaces two hydrogen atoms and forms zinc bromide.

Step 6: Write balanced chemical reaction of equation (c)

The balanced reaction is:

$Zn\left(s\right)+2HBr\left(aq\right)\to ZnB{r}_{}\left(aq\right)+H_2\left(g\right)$

Step 7: Determine the product of the equation (d)

The given redox reaction is a displacement reaction.

Bromine displaces iodide from potassium iodide molecule and forms potassium bromide.

Step 8: Write balanced chemical reaction of equation (d)

The balanced reaction is:

$2KI\left(aq\right)+B{r}_2\left(I\right)\to 2KBr\left(aq\right)+I_2\left(s\right)$

Step 9: Determine the ionic equation

The balanced equation is:

$2KI\left(aq\right)+B{r}_2\left(I\right)\to 2KBr\left(aq\right)+I_2\left(s\right)$

Now, the total ionic equation is:

$2K^{+}\left(aq\right)+2I^{-}\left(aq\right)+B{r}_2\left(I\right)\to 2B{r}^{-}\left(aq\right)+I_2\left(s\right)$

Step 10: Net ionic equation

K⁺ is the spectator ion in the total ionic equation and it will not be present in net ionic equation. Hence the net ionic equation is

$2I^{-}\left(aq\right)+B{r}_2\left(I\right)\to 2B{r}^{-}\left(aq\right)+I_2\left(s\right)$