[whimsical create]

Trying to come up with an IA on titration ( finding phosphoric acid content in a type of soda) but have to have at least 5 independent variables? Any suggestions?

Also I only have methyl red to work with...would this work? Or do I just use a ph meter because of the dark color of the soda - won't be able to see color change? My teacher said that using just a ph meter wouldn't be reliable to do a titration.

[Borek]

Trying to come up with an IA on titration ( finding phosphoric acid content in a type of soda) but have to have at least 5 independent variables? Any suggestions?

Five is a lot, unless you are expected to just list them and ignore. Things like temperature or partial pressure of CO₂ are always present, are definitely independent and definitely influence the titration result - by a negligible amount.

My teacher said that using just a ph meter wouldn't be reliable to do a titration.

I am afraid I have to disagree with your teacher, pH meter is typically the most reliable instrument in such cases.

You can always try to remove the coloring with activated carbon, or oxidize it with bleach. Don't forget to use exactly the same amount of whatever you decide to use in each sample and to do a blank test, so that you can correct your titration result.