Hey, 1)What are the solvents that could be used in chromatography? + 2)What is meant by the terms excess and concentrated? -i know what do they mean but i dont know what 2 write 
- + 3)Why is crushing with sand helpful? + 4)What are the conditions for rusting, and explain what happenes + 5)while calculating the temperature difference, is it initial-final or final-initial? + 6)How can the purity of a liquid -such as ethanol- be checked? + 7)why ninhydrin and locating agents are used?
I know thats alot, but i'd appreciate any answer, Thanks
1) Water, or organic solvents, such as ethanol, depending what the dyes are soluble in.
2) -Excess refers to a substance in a greater quantity than the minimum quantity required to complete the reaction.
-A solution is concentrated when it contains a greater quantity/concentration i.e more solute than solvent.
3)To remove solid impurities, i guess. :S As it acts like a filtering sieve? :S
4)Oxygen and Water are required for rusting. i.e, HYDRATED IRON OXIDE (Fe2O3.xH20) forms, where x is the number of molecules of Water. This hydrated iron oxide is a reddish-brown layer, which when covering iron on steel, i.e corroding it, is specifically termed as rusting.
5)Final-Initial. Yes, the temp. diff. can be -ve. Examples of +ve and -ve graphs are there in past papers.
6) Umm, by checking the boiling point. Pure ethanol has a boiling point of 78 deg. C.
7) Often the amino acids or results of separating dies formed on the chromatogram ARE COLOURLESS/INVISIBLE, so to make them visible, so that they may be 'located', such agents are used.
Hope that helped.
