urgent ... help

[Jenz08]

how many grams of sucrose is needed to make up 0.2m in a 200cm solution??

[Pigletion]

Sucrose molecular weight = 342 (approx will say exact on side of jar), i.e 1 M solution is 342 g of sucrose in 1 L of water.

0.2 M is therefore 342/5 = 68.4 g in 1 L.

I don't understand the 200 cm, but hope this helps. I'm sure you can work out the ratio you need from 1 litre.

[Jenz08]

Thankyou, you did it the same way as i did and i got that answer also, but i needed to get 17.35g...

I did manage to work out how to get 17.35 grams; But i had to used 250cm instead; So all i had to do was to take the moles and times it by the volume (dm3) and then times by the RMM;

0.2 x 0.25 x 347.5 (as on side of the bottle)

[Pigletion]

So did you only want 200 ml? If so that's 1/5 of a litre,

so 0.2 M is therefore 342/5 = 68.4 g in 1 L

therefore

0.2 M in 200 ml is 68.4/5 = 13.68g in 200 ml water.

[Jenz08]

It was 250ml of water which i used.