Equilibrium, Charge Balance, Mass Balance

[whatlifeforme]

1. The problem statement, all variables and given/known data

Write the charge balance for a solution containing H(+), OH(-), Ca^(2+). HCO3(-). CO3^(2-) , Ca(HCO3)+, Ca(OH)+, K+, and CIO4(-).


2. Relevant equations

Also, I am having a trouble understanding the concepts of mass balance and charge balance.

3. The attempt at a solution

The only thing I know to do is put the positive charges on one side and the negatives on the other, and then change the coefficients.

[studiot]

Well it would appear to be the aqueous calcium carbonate system with some potassium perchlorate thrown in to spice things up.

 

You are on the right track with the charge balance.

 

The first thing you need to do is to assign a coefficient to each species eg a(H+); b(OH-); c(Ca2+)....e(CO₃2-).... and so on.

 

They represent the relative numbers of each ion present in the solution.

 

These coefficients are pure numbers and will normally be the smallest set of numbers that satisfy both the charge and mass balance requirements. At the outset they are unknown and your task is to determine them from the question data.

 

What you then need to do is write down a numeric equation ie containing numbers only connecting the coefficients and

 

the charges on the ions - this is the charge balance equation and yes you collect positive on one side and negative on the other.

 

eg from my list above

 

(ax1) + (cx2) = (bx1) + (ex2)

 

As to the mass balance, which you have included in the question title, this is where you introduce context data such as 150g of calcium bicarbonate were dissolved in 1.5 litres of water.........again connecting the coefficients to each other but this time via the mass quantities and molecular weights of the species involved and the chemical reaction equation or (in this case equations) involved. You should remember that the solvent may also play a part with some of the species.

 

 

We can also discuss this further if you wish.

Edited August 23, 2013 by studiot