When 2.4 g of Co(NO3)2 is dissolved in 0.350 L of 0.22 M KOH, what are [Co^2+],[Co(OH)4^2-], and

step 1 Question 104 is very similar to question 103. It is a complex ion formation question where knowi

When 2.4 g of Co(NO3)2 is dissolved in 0.350 L of 0.22 M...

Key Concepts

Molarity and Concentration

This concept involves converting between the number of moles of a solute and its concentration in solution by using the volume of the solution. It is crucial for setting up calculations in solution chemistry, where the molarity is defined as moles of solute per liter of solution.

Reaction Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It allows the determination of how many moles of a substance react or form during a chemical process based on the balanced chemical equation, which is essential in quantifying reactions in solution.

Limiting Reagent Concept

The limiting reagent is the reactant that is completely consumed first in a chemical reaction, thereby determining the maximum amount of product that can be formed. Recognizing the limiting reagent is important for accurate stoichiometric calculations, especially when reactants are provided in different amounts.

Complex Ion Formation Equilibrium

Complex ion formation occurs when a metal ion bonds with one or more ligands, leading to the formation of a complex. This process is governed by equilibrium principles where the formation of the complex ion can shift the concentrations of the involved species in solution.

Formation Constant (Kf) and its Significance

The formation constant (Kf) is the equilibrium constant for the formation of a complex ion from a metal ion and its ligands. A high Kf value indicates that the complex is very stable and forms almost completely, which is crucial when predicting the concentrations of various species in a solution undergoing complexation.

Transcript

00:01 Question 104 is very similar to question 103.

00:06 It is a complex ion formation question where knowing the equilibrium for the formation of the complex ion, the cobalt with four hydroxides, we should be able to salt and the kf value for the formation of that complex ion, we should be able to once equilibrium has been reached, solve for the final cobalt concentration, the final hydroxide concentration, and the final complex ion concentration.

00:39 We'll do what we did, similar to question 103.

00:43 Let's first identify the equilibrium that creates the complex ion with its corresponding kf expression and kf value.

00:54 We have cobalt 2 plus reacting with four hydroxides, producing the complexion.

01:00 Complex ion of cobalt with four hydroxides and a total two minus charge.

01:05 The kf expression is going to be the product concentration minus the reactant content, i'm sorry, divided by the reactant concentrations, which is what we have here, product concentration divided by the reactant concentrations, each raised to their corresponding coefficient.

01:23 So the only one that has something other than one is hydroxide, which is raised to the fourth power.

01:28 And that kf value was given to us at 5 times 10 to the 9.

01:36 We can solve for the cobalt concentration once equilibrium has been established, by first determining the concentration of cobalt before equilibrium has been established, by recognizing we added 2 .4 grams of cobalt 2 nitrate.

01:55 If we take the mass of cobalt 2 nitrate, divide by the molar, mass of cobalt 2 nitrate.

02:02 This will give us the moles of cobalt 2 nitrate that we have in solution before equilibrium is established.

02:08 We divide by the volume of the solution, which was given to us at 0 .35 liters.

02:15 This will be the molarity of cobalt 2 plus before equilibrium has been reached.

02:21 Once equilibrium has been reached and we form the product, then cobalt 2 plus will be consumed by a certain amount we will call x.

02:31 So we have minus x here.

02:35 If i finish the calculation as much as i can, the cobalt concentration will be equal to this number, 0 .03748 minus x.

02:46 Now let's look at the hydroxide concentration...

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