2.3 & 2.4 Flashcards
paper chromatography and planning a solubility investigation
what is paper chromatography?
the technique used to separate out coloured inks
what is a chromatogram?
the resulting image on the paper
why do the coloured inks separate?
water dissolved them. as the water moves up the paper it carries the ink particles with it
why do you have to dry the spot of ink before adding more?
so that the chromatography paper doesn’t tear because its very thin and can tear with too much ink put on.
why is it important not to let the ink spot go under the water?
so that the ink doesn’t just dissolve in the water, but actually travels up
why are different kinds of ink particles carried different distances?
because not all the ink particles have the same solubility, the more soluble the ink, the further its particles are carried.
how would you know if the ink is a pure substance, containing only one substance?
there would be only one colour, not different colours.
explain why a scientist should carry out further tests on a colouring that is not on the list of permitted colourings.
they must make sure its reliable and to check and confirm the previous results. if its confirm then they should suggest to stop the production of that drink.m
Alex and Harper are asked to compare solubility of two salts in water at room temperature. the two salts are labelled Y and X.
Name the independent, dependant and 2 control variables.
independent: the type of salt
dependent: the solubility of salt
control: temperature must be room temperature
volume of water
the mass of salt must be same
Alex and Harper are asked to compare solubility of two salts in water at room temperature. the two salts are labelled Y and X.
Describe how the carry out their investigation.
first, they prepare 2 beakers of water at keep them at rooms temperature. next, they put salt X is one beaker, and salt Y in the other. then they turn on the stopwatch to see how fast one salt dissolves, then move on to the next salt and do the same. they record the results of the time taken to dissolve each salt.
