in one of the routine analyses, dr entropy found that the concentration of phosphate had increased from 0.0090 mg/l to 0.220 mg/l. this will require a lengthy investigation and detailed report into the causes. being the master of disorder, he considers an act of serious scientific misconduct - diluting the sample to reduce phosphate concentration to the maximum allowable level of 0.100 mg/l, and hoping that no-one notices.
if the volume of the original sample with concentration 0.220 mg/l is 10.0 ml, what should be the final volume of solution in order to dilute it to 0.100 mg/l?

thats how its supposed to be

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.