Science Buddies: "Ask an Expert"

My daughter is working on the taste threshold experiment. Instructions say to get a 10% vinegar and water solution, mix 2ml vinegar and 18ml water. Please explain how to get 1%, 0.1%, 0.01% solutions? We need this right away. Thank you.

Good morning, Terie,

My first question is how much of each solution do you need? Assuming that you do not need a great deal, say, less than 20 ml, here's how you go about making your solutions:

Your first solution is 10 % vinegar, and you have made a 20 ml solution (2 ml of vinegar plus 18 ml of water).

To make a 1 % solution, take 2 ml of the 10 % solution and dilute it to 20 ml with water (that is, add 18 ml of water). This is a ten-fold dilution, so 10 % goes to 1 % - does that make sense?

(It is worth pointing out that you should always add the acid to the water, just to be safe. Using dilute acetic acid (vinegar) won't be hazardous in this context, but it is dangerous when using stronger and more concentrated acids.)

To make a 0.1 % solution, take 2 ml of your newly-made 1 % solution and dilute this to 20 ml (so 1 % goes to 0.1 %, another ten-fold dilution).

To make a 0.01 % solution, take 2 ml of the 0.1 % solution and dilute this to 20 ml (0.1 % goes to 0.01 %, a ten-fold dilution).

This process can continue until you have produced all of the solutions you need!

Of course, if you require more than 18 ml of each solution, then the calculations will be proportionally larger. Please let us know if you have any more questions, and good luck!

Geoff.

Hi Terie,
I agree with Geoff's expert advice. I just wanted to add that for doing this experiment with vinegar, the recommendation to use distilled water will be more important, because undistilled water, especially water from wells, will tend to contain dissolved minerals that neutralize the vinegar.
Good luck!
Chris

Thank you so much You have been a big help.

You're welcome! Glad to be of some assistance. Are you able to use distilled water for your experiment, as Chris suggested? (Thanks for catching that, Chris!)

If you have any more questions, please be sure to let us know.

Best wishes,
Geoff.