how to I calculate 0.50% w/w phenolphthaleine solution from a 70 ppt phenolphthalein solution? Sol'n pls.?

Answer 1

70 ppt is 70 parts per thousand, or 70g in one kg.

This is 0.7% w/w

To get 0.5% you need 50g in one kg., or 70g in 70/50 = 1.4kg

Therefore add solvent until the original solution's total weight increases by 40%.

Answer 2

Phenolphthaleine

Answer 3

Specify the volume.