# Chem. Prob.

1. Jul 8, 2008

### nikkee

Could someone explain to me how to solve this?

I have a 10 gallon solution made up of 6.40%Cl, 5.52%Na, and 4.11%Ca, with a density of 1.21. How much HCl is needed to get the %Cl up to a 6.60%, and what would the theoretical %Na and %Ca be after the HCl addition?

Can anyone show me the steps to solve this?

2. Jul 8, 2008

### symbolipoint

How about just a couple of hints!

The density information is only to help start the solution of the problem. You are adding a number then to both the mass of the liquid and to the mass of Cl, from the addition of HCl. (we notice that your concentration of HCl source is not given).

3. Jul 8, 2008

### nikkee

The concentration of the HCl is ~32% by weight.

4. Jul 9, 2008

### lewdtenant

You absolutely need to pay attention to units. What are the units of density you have given?

I'm assuming your percentages are by weight. Figure out how much mass you have in ten gallons of solution; use molecular weights to do this.

That would be a good starting point.

5. Jul 9, 2008

### symbolipoint

You will need to check a handbook unit conversion ratios to go from gallons to pounds, which is why you will need also to convert the density into pounds/gallon. The best of memory suggests that 453.59 grams = 1 pound; 2850 milliliters = 1 gallon. Convert your 10 gallons of mixture to its number of pounds.

Now, you need to choose a variable to apply to both the numerator and denominator of a ratio representing the "percent" of Cl. The variable will be the amount of mass of HCl solution which you want to add to your 10 gallons of mixture. I will leave all of the algebraic transcription to you.

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