E6 Water Treatment

this image is a blank and white image of the water system through each pipes and drains and how it gets cleaned and transferred through the system in a diagram.

this image talks about the water treatment system and how the water transfers from each system and leads to the soil and roots at the end of the image.

review questions;

Waste water can contain metal ions such as chromium. Chromium ions can cause damage to the liver and kidneys. Chromium ions can be removed from water by chemical precipitation using hydroxide ions.

(a) Assuming chromium is present as Cr3- , state an equation for its reaction with hydroxide ions, include state symbols. [2]

(b) State an expression for the solubility product constant, K, for chromium (III) hydroxide. [1]

(c) The solubility product of chromium (III) hydroxide is 1.00×10-33 mol4 dm-12 at 298 K. Calculate the concentration, in mol dm-3, of Cr3+ in the solution, when chromium (III) hydroxide is precipated. [2]

1.   (a) Two processes used to treat sewage are filtration and chemical precipitation.

(i)  Name the type of substance removed by filtration and the equipment used to do this. [2]

(ii) Name the type of substance removed by chemical precipitation and a chemical used to do this. [2]

(b) (i)  State two advantages of treating drinking water with ozone rather than chlorine. [2]

(ii) Other than cost, name one disadvantage of treating drinking water with ozone  rather than chlorine. [1]

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One Response to E6 Water Treatment

  1. acelapat says:

    a.Cr2(SO4)3(aq)+6NaOH(aq)=>2Cr(OH)3(s)+3Na2SO4(aq)
    b.Ksp=(Cr3+)1(OH-)3
    c.2.5×10-33M
    1a.
    i. Carbon filters the Chlorine in water and that’s according to http://www.historyofwaterfilters.com/filtration-process.html
    ii Alum is used to react with carbonate or hydroxide to form precipitate which can be used in water treatment according to the http://water.epa.gov/scitech/wastetech/upload/2002_06_28_mtb_chemical_precipitation.pdf
    1b.
    i Ozone is known to be more healthier water treatment than chlorine.
    ii Chlorine in the other hand last longer according to http://www.ozoneapplications.com/info/ozone_vs_chlorine.html

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