Wednesday, 13 February 2013

1.4 describe and explain experiments to investigate the small size of particles and their movement including: i dilution of coloured solutions ii diffusion experiments

Dilution: a substance is put in a solvent to reduce its concentration
Diffusion: The movement of particles from an area of high concentration to an area of low concentration

Experiment 1, Diffusion
Hydrochloric acid is placed at one end of a tube, ammonia solution at the other.
Where they meet a ring of ammonium chloride appears.
The diagram shows it is closer to the HCL end.
From this we can tell that ammonia must have travelled faster, as it got further in the time. Lighter particles travel faster- so we can tell that ammonia is a lighter gas.




Experiment 2, Dilution
Put a coloured substance in a solvent e.g food colouring in water.
You can see that over time the colour levels out but is weaker than the original colour- this is dilution.
Dilution at different temperatures: more heat; means more energy; means more movement; so the particles can move to different areas more quickly. So applying heat decreases the amount of time taken for the coloured substance to be fully diluted.

18 comments:

  1. Thank for the Blog its really helping me out

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    1. http://www.rsc.org/learn-chemistry/wiki/TeacherExpt:Diffusion_of_gases_-_ammonia_and_hydrogen_chloride it actually forms near the hydrochloric acid side.

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    2. Thank you very much! let me change that ;P

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  2. Hannah, have you got any other Revision Blogs for any other subjects and have you finished your IGCSEs?

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    1. I just have this blog and one for physics (hannahhelpphysics.blogspot.co.uk)and one for biology(hannahhelpbiology.blogspot.co.uk). I haven't finished yet, I am currently doing the exams: I have done all the paper 1s and in two weeks I will have done the paper 2s aswell!

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    2. Thanks for this! Really useful

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  3. Hannah, maybe you could do a site with GCSE exam tips (in particular for the sciences)? it would be really useful since you experienced them first-hand:)

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  4. This comment has been removed by the author.

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  5. "it is closer to the ammonia solution... that ammonia must have travelled faster". Not sure if that's correct, but I may be wrong.

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  6. If the ammonia particles travel faster then the ring should form closer to the hyrdrochloric acid.

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  7. Hannah,can you help me to solve this chemistry question?
    what is relationship between diffusion and space between particles?

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  8. Thank you so much! Can't tell you how much this has helped me xx

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  9. for the diffusion experiment, wouldn't it be hydrogen chloride gas rather than hydrochloric acid, as it is talking about diffusion?

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  10. The Chemistry Syllabus has changed…

    Here is a New blog for the 2017 Syllabus:

    https://igcse-chemistry-2017.blogspot.hk/

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