Cobalt form complex ions with water and chloride as shown in the reactionThe left side of the reaction is pink, and the right side of the reaction is blue. Co(H 2 O) 6 ^ 2+ +4Cl^ - +heat Rightarrow CoCl 4 ^ 2- +6H 2 O Which statement about the system at equilibrium is correct?
The concentration of CoCl4^2- is greater than the concentration of Co(H2O)6^2+.
The statement about the system at equilibrium that is correct is that the left side of the reaction is pink, and the right side of the reaction is blue.
To determine the correct statement about the system at equilibrium, it's important to understand the concept of Le Chatelier's principle. According to this principle, when a system at equilibrium experiences a change in conditions, it will shift in a way that minimizes the effect of the change.
In the given chemical reaction, cobalt ions (Co²⁺) form complex ions with water (H₂O) and chloride ions (Cl⁻). The left side of the reaction represents the complex with six coordinated water molecules (Co(H₂O)₆²⁺), which appears pink. On the right side of the reaction, the cobalt ions form a complex with chloride ions (CoCl₄²⁻), resulting in a blue color. The reaction is exothermic, indicated by the heat symbol.
Now, let's consider the statements:
1. Adding more chloride ions will cause the reaction to shift to the left.
2. Increasing the temperature will cause the reaction to shift to the right.
3. Removing water molecules will cause the reaction to shift to the left.
4. Decreasing the temperature will cause the reaction to shift to the left.
To evaluate these statements, let's apply Le Chatelier's principle to determine the effect of the changes.
1. Statement 1: Adding more chloride ions will cause the reaction to shift to the left.
According to Le Chatelier's principle, if we add more chloride ions (Cl⁻), the system will shift to the left to minimize the effect of the increase. Consequently, the reaction will favor the formation of Co(H₂O)₆²⁺, resulting in a pink color. Therefore, statement 1 is incorrect.
2. Statement 2: Increasing the temperature will cause the reaction to shift to the right.
In an exothermic reaction, increasing the temperature typically favors the reverse reaction to absorb the excess heat. Since the reaction is exothermic and the formation of CoCl₄²⁻ is favored by a decrease in temperature, statement 2 is incorrect.
3. Statement 3: Removing water molecules will cause the reaction to shift to the left.
Since the formation of complex ions involves water molecules (Co(H₂O)₆²⁺), removing water molecules will shift the equilibrium towards the side with more water molecules. Therefore, the reaction will favor the formation of CoCl₄²⁻, resulting in a blue color. Thus, statement 3 is incorrect.
4. Statement 4: Decreasing the temperature will cause the reaction to shift to the left.
As mentioned earlier, the reaction is exothermic, and decreasing the temperature will shift the equilibrium to the left to absorb the excess heat. The formation of Co(H₂O)₆²⁺ will be favored, resulting in a pink color. Therefore, statement 4 is correct.
In conclusion, the correct statement is: "Decreasing the temperature will cause the reaction to shift to the left."