[gakgx6]

0.2 molar acetic acid- % solution=Molarity x molecular weight/10=0.2 x 60/10=1.2%.
1.2 gram of acetic acid per 100 ml water. If I add 20 ml of water, then I have 1.2 gram acetic acid per 120 ml water=1% acetic acid. How do I figure out how much of chitosan i need to add?

I was thinking to add 1 gram chitosan, am I correct?

[Borek]

1g per 120mL (more or less 120g) will be not 1%, more like 0.8%.

[gakgx6]

1g per 120mL (more or less 120g) will be not 1%, more like 0.8%.

Sorry I meant 1.2 gram. Will my method be the right one to make the 1% acetic 1% chitosan?

[Borek]

To be exact you should take even a little bit more than 1.2g, as final mass will be 120g plus the mass of chitosan added, so the concentration will be 1.2/(120+1.2)*100%. But the error is so small you can safely ignore it. Your method looks reasonably good.