Question

Theory Topics - Explain why inexpensive Calorimeters must use Small quantities of reactants and low concentrations Describe how a (Cerror in temperature reading con lead to a large error overall in this lab. AH calculation

Answer 1

It involves the quantitative estimation of colour. A substance to be estimated colorimetrically must be coloured or it should be capable of forming chromogens (coloured complexes) through the addition of reagents. coloured solution have a property of absorbing certain wavelength of light when a monochromatic light is passed through them. The amount of light absorbed or transmitted by by a coloured solution is in accordance with two laws : Beers law & Lamberts law

Beers law : When a monochromatic light passes through a coloured solution, amount of light transmitted decreases exponentially with increase in concentration of coloured substances. i.e. the amount of light absorbed by a coloured solution is directly propottion to the concentration of substance in the coloured solution.

Lamberts law : the amount of transmitted light decreases exponentially with increase in path length (diameter) of cuvette or thickness of colored solution through which light passes i.e. the amount of light absorbed by a colored solution depends on the pathlenght of cuvette or thickness or depth of colored solution.

Combines berrs-lamberts law : the amount of light transmitted through a colored solution decreases exponentiallly with increase in concentration of colored solution & increase in concentration of colored solution & increase in pathlength of cuvette or thickness of colored solution.