# Diluting the stock solution with ethanol

1. Feb 12, 2005

### physicsss

I think the idea is you are diluting the stock solution with ethanol...how do I calculate how much the concentration is in the solution X and Y?

ignore those lines...I had to use those to line the data up.

Last edited: Feb 12, 2005
2. Feb 12, 2005

### Gokul43201

Staff Emeritus
What is the definition of the concentration ? And what does the first line tell you ? And how do you think the dilution factor is defined ?

You ought to show some effort before asking for help, physicsss.

3. Feb 12, 2005

### physicsss

All I'm given is that V1C1=V2C2..., but the volume adds up to 3.0mL. I don't know what the dilution factor means.

Last edited: Feb 12, 2005
4. Feb 12, 2005

### Gokul43201

Staff Emeritus
Can you write down the question EXACTLY as it appears in your homework/text ?

5. Feb 13, 2005

### physicsss

This is all I'm given. I'm diluting the stock solution with EtOH. And I'm to"complete the missing entries given the table below:"
http://www.geocities.com/sinceury/untitled.JPG

6. Feb 13, 2005

### Gokul43201

Staff Emeritus
Okay, that's fine.

Notice that by the definition of dilution factor (volume of stock / total volume), the numbers in the first two colums are consistent with the numbers in the third column.

Example : (row 2) DF = 2.5/(2.5 + 0.5) = 2.5/3 = 1/1.2
In this manner you can calculate the DF for other rows.

The first row tells you the concentration of sunscreen in the stock (.0898 g/mL). Knowing how much sunscreen there is in 1 mL, you can then find out how much there will be in 2.5 mL, 2 mL, 1.5 mL, etc. (the volumes of the different stock solutions). Dividing these weights by the total volume gives you the concentration for each case.