# What Is the Molarity of Potassium Ions in a Potassium Sulfite Solution?

• jackthehat
In summary, Jack has attempted to solve a problem involving finding the molar concentration of potassium ions in a solution of potassium sulfite. He has broken down the process into three steps, finding the molarity of the solute, calculating the ion-to-solute ratio, and finding the ion molarity. His final answer is 0.632M. He asks for input on whether he is approaching the problem correctly.
jackthehat
Hi,
I have a problem which I have attempted to solve several times without success and i am at a loss to know where I am going wrong. The problem is ..

If 10.0 g of potassium sulfite is dissolved in water to make 200.0 mL of solution, then what is the molar concentration of potassium ions in the solution? (Hint: You should write a balanced chemical equation for the dissolution of potassium sulfite in water.)

My attempt ..
I did the thing in 3 steps ..
Step 1 - Find the Molarity of the solute ..
First find formula of compound .. compound comprises 2 elements 'K' (1+ ionisation number) and 'SO3' (2- ionisation number) so formula for compound is ... K2SO3 .. Molar mass of K2SO3 is ((2x39.098)+(1x32.06)+(3x15.999)) g/mol = 158.253 g/mol.
So Moles of (K2SO3) = (10.0 g/158.253) mol = 0.0632 mol
Now we have to account of the volume of the solution ..
Moles of solute (in solution) = 0.0632/100ml x 1L/1000ml = (0.0632 / 0.200) mol = 0.31595 mol

Step 2 - Find 'ion-to-solute' ratio
Reaction equation - K2SO3(s) --> 2K 1+ + SO3 2-
From the above reaction equation we see 2 moles of K1+ are produced from 1 mole of K2SO3 .. ratio is 2moles (K1+)/1 mole (K2SO3) =2/1

Ste 3 - Find ion molarity
Molarity of K1+ ion = Molarity of K2SO3 x (2/1) = 0.3159 x 2 = 0.63190 M .. ~ 0.632M (to 3 significant figures).

Am I attempting this all wrong or am I doing it the right way .. can you help please ?
Regards
Jack

Last edited by a moderator:
Everything looks fine to me.

jim mcnamara
Ygggdrasil said:
Everything looks fine to me.
Hi Ygggdrasil ,
Thanks for taking the time to have a look at my problem and for your input.
Regards,
Jack

## What is the definition of molarity of ions in a solution?

Molarity of ions in a solution refers to the concentration of ions in moles per liter of solution. It is a measure of the number of ions present in a given volume of solution.

## How is molarity of ions in a solution calculated?

Molarity of ions in a solution can be calculated by dividing the number of moles of ions present in a solution by the volume of the solution in liters. This is represented by the formula M = n/V, where M is molarity, n is the number of moles, and V is the volume in liters.

## Why is molarity of ions in a solution important in chemistry?

Molarity of ions in a solution is important in chemistry because it helps to determine the reactivity and behavior of ions in a solution. It also plays a crucial role in various chemical reactions and is used to calculate the concentration of solutions in experiments.

## How does temperature affect the molarity of ions in a solution?

Temperature can affect the molarity of ions in a solution because it can change the volume of the solution. As temperature increases, the volume of the solution also increases, resulting in a decrease in molarity. This is known as thermal expansion.

## What factors can affect the molarity of ions in a solution?

The molarity of ions in a solution can be affected by factors such as temperature, pressure, and the presence of other solutes. Changes in these factors can alter the volume and concentration of the solution, thus affecting the molarity of ions present in the solution.

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