Question

HELP!
It was observed that the longer the pine drink was set, the more sour it tasted once it was left uncovered. A science student predicted that this was due to the presence of ethanoic acid in the pine drink. According to him, the lower the pH, the stronger the sour taste. Plan and design an experiment to investigate the student's claim.

All i need is the experiment concept and i'll continue from there. Thanks in advance.

Answer 1

okay, so you always start of with an hypothesis;

ours could be: we believe that the lower the pH the more sour the pine drink will taste,

Answer 2

@kym02 We could measure the amount of time the drink was set, in minutes. then measure the pH. and the taste as well.

Answer 3

the pH and time are related so we would measure both. we know that if it's sour then there's bound to be acid in there. we measure the pH after say maybe intervals of five minutes.

Answer 4

alright...got it. Where does the ethanoic acid come in all of this?

Answer 5

it's believed that the ethanoic acid is the cause of the sourness.

Answer 6

we need to first figure out whether the drink tastes sour and whether that relates to a lower pH or not

Answer 7

this is a stretch but after we do that we could easily say maybe identify the compound by some type of spectroscopy

Answer 8

make sense?

Answer 9

I'm trying to make sense out of all this but i'm failing quite miserably. I understand that the longer the pine drink is out, left uncovered, the more ethanoic acid will be fermented. Now, where is this CH3COOH coming from? since the pH and time is related, i'll have to provide a discussion and my control, responding and manipulated variable and just thinking about it makes me want to stare at the wall.

Answer 10

Also, is it wise to include a control? say, one is uncovered and the other, covered?

Answer 11

that's interesting. it wasn't really mentioned yeah great observation though. there could be some reaction occurring, but I think a control would be maybe you have two groups right?

one you introduce ethnanoic acid into the drink, and then measure the pH change and sourness over time.

the second group you just leave the drink out and do the same thing.

Answer 12

@kym02 I assume that the ethanoic acid forms, by some kind of reaction, due to it sitting out longer. maybe carbon dioxide is being absorbed into the solution, that's a stretch but hmm..

the idea is that acid is forming the longer you keep it out. but the thing is @kym02 we dont know if there's acid in there to begin with. that's why I suggested introducing ethnoic acid into the drink for a second group and seeing what happens.

Answer 13

And that's what was bugging me. At first, I assumed that there was an acetic acid bacteria that converts ethanol to acetic acid in the presence of oxygen (the uncovered pine drink) but the thing is, where does the ethanol come from?

Answer 14

I think maybe for the purposes of this experiment you're just suppose to determine whether there's acid in there.

Answer 15

reason why I said to put ethnoic acid into one group and leave the other one dormant is to check to see if some other medium is required other than just leaving it out.

Answer 16

Alright, that will definitely work then. If that way is done, what exactly are the materials/ apparatus that should be used. That's all i need to know in terms of clearing everything up in my head.

Answer 17

or

Answer 18

I honestly can't see the words at the end :s they were cut short.

Answer 19

oh, it's better now.

Answer 20

have a computer that measures the pH in certain time intervals, then you could just take a small bit of the solution out and taste it to determine sourness.

Answer 21

alright, Thanks a bunch for your help!

Answer 22

also, is there any sort of limitation or sources of error? *_*

Answer 23

I guess it's like how do you measure sourness that's a big limitation that's more qualitative that quantitate.

Answer 24

well that's more of a limitation than a source of error

Answer 25

okay. Thanks you very much, once again ^_^