I had this high school project and my experiment involves using coconut water as a culture medium.
what perplex me is that when i add agar-agar to coconut water the volume increase?!
-what i do know from what my chemistry teacher told us is that when you add more mass it won't increase the volume but the density will increase
In my experiment, i had to make a ratio for the right mix not too soft and not to hard
the manufacturer's instructions said mix 90 g of agar-agar into 400 ml of water
Hench to make 1000 ml media i use a basic ratio and portion formula
M1/V1 = M2/V2
90g/ 400ml X n/1000ml
(90 g X 1000 ml) / 400 ml = 225 g
thus i added 225 g agar- agar to 1000 ml coconut water but what happened next disappoints me,
the volume increased it went way over the 1000 ml mark in my Erlenmeyer flask, but i still proceed with it.
it remained to be over 1000 ml mark after cooling it to room temp and worst of all the coconut agar was too soft
The next idea i had was to subtract 1000 mL and 225 g
so tried i subtracted 1000 by 225 and gave me 775
giving me a ration of 1:3.4
(density of coconut water is about 1.02 g/mL at 20 deg. Celsius basically it's near the density of water 1.0 g/mL
http://www.fruits-journal.org/articles/fruits/pdf/2012/03/fruits120009.pdf)
Hench i used 225 g of agar -agar and mixed it with 775 ml of coconut water
i did just that and it gave me a little below the 1000 mL mixture maybe around 990-999 mL. After heating, the media cooled and solidified they way i wanted not to soft and not to hard
I'm already finished with this project and my teachers never question the ratio i pulled out they just focused if i could grow things on it, i even got an A +
been weeks after that but it's still on my mind. It seems to break the laws of physics, it's too surreal because
the mass of the agar-agar added on to the coconut water what happen its like 225 g + 775 mL = about 1000 mL medium but not exactly 1000 mL
is that even possible? is there other laws behind it? i do know solvent increase the volume of the solute but not that significant unlike the case here.
I didn't have any pure cultures of any organisms to grow so i used banana, orange fruit peels, and leaves
results was a lot of fungi and yeast grew on it
sorry i have no pictures of it.
and sorry if bad english it's not my1st language
