How Do You Calculate pAg in Precipitation Titrimetry?

[Pruddy]

Homework Statement

Calculate the pAg after the addition of 5ml, 40ml, and 45ml of 0.05M AgNO3 to 50.00ml of 0.04M Kbr (AgBr Ksp = 5 x 10^-13)

Homework Equations

The Attempt at a Solution

when 5ml of AgNo3 is added , we have
(50 x 0.004 - 5 x 0.05)/55
= 0.0318
P(kbr) = -log 0.0318
= 1.497

The point is that I don't know when and how to calculate the Pag. I find this topic very confusing.I will be very gratefull if anyone can give me a hint on how to solve this problem. Thanks

 

[Borek]

What is the definition of pAg?

 

[Pruddy]

PAg means the P-function of Ag.

 

[Borek]

So what do you need to calculate pAg? (note the capitalization - pAg, not PAg, just like pH and not PH).

 

[DeeNos]

!

Precipitation titrimetry is a technique used to determine the concentration of a substance in a solution by measuring the amount of a precipitate formed. In this case, we are looking at the precipitation of silver bromide (AgBr) from the reaction between silver nitrate (AgNO3) and potassium bromide (KBr).

To calculate the pAg, we first need to understand what it represents. pAg is the negative logarithm of the silver ion concentration (Ag+) in a solution. In this case, we are dealing with a mixture of two solutions - 0.04M KBr and 0.05M AgNO3. When these two solutions are mixed, a reaction occurs and some of the silver ions (Ag+) combine with bromide ions (Br-) to form a precipitate of AgBr. The remaining silver ions will still be present in the solution.

To calculate the pAg, we need to know the concentration of the remaining silver ions in the solution. This can be determined by using the concentration of the original solutions and the volume of each solution added. In this case, we are adding 5ml, 40ml, and 45ml of 0.05M AgNO3 to 50.00ml of 0.04M KBr.

Using the formula for dilution, we can calculate the final concentration of silver ions in the solution after each addition. For example, after adding 5ml of 0.05M AgNO3, the final volume of the solution will be 55ml (50ml of 0.04M KBr + 5ml of 0.05M AgNO3). Plugging these values into the formula C1V1 = C2V2, we get:

(0.05M)(5ml) = (C2)(55ml)
C2 = 0.004545M

This means that after adding 5ml of 0.05M AgNO3, the concentration of silver ions in the solution is 0.004545M. We can repeat this calculation for the other additions and use this concentration to calculate the pAg using the formula -log[Ag+].

I hope this helps clarify how to approach this problem. If you have any further questions, please don't hesitate to ask.