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What chemical compounds might be present in drinking water?
What chemical compounds might be present in drinking water?

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Summary of Section 3

  • Phosphate is used in fertilisers and excess phosphate in natural water can cause eutrophication.
  • Phosphorus has several acids including phosphoric and phosphorus acid. Note the higher oxidation number, or oxidation state, is indicated by the suffix -ic and the lower oxidation state by the suffix -ous.
  • Generally for oxoacids if more than two oxidation numbers are involved, the prefixes per- and hypo- are used as well where per- denotes the highest oxidation number and hypo- the lowest oxidation number.
  • Some acids of phosphorus are polyprotic. For instance, phosphoric acid:
    H3PO4(aq) = H+(aq) + H2PO4(aq)
    (Equation 21)
    H2PO4(aq) = H+(aq) + HPO42−(aq)
    (Equation 22)
    HPO42−(aq) = H+(aq) + PO43−(aq)
    (Equation 23)
  • Deprotonation of an acid yields its conjugate base or anion. In Equation 21 H2PO4 is the conjugate base of phosphoric acid.
  • Oxoacids and oxoanions can polymerise by condensation.
  • Phosphorus also forms polyacids containing two or more acidic phosphorus centres.
  • Polyphosphate can form chain or ring polymers.
  • Adenosine triphosphate (ATP) stores energy in the body which is released upon its hydrolysis to adenosine diphosphate (ADP).
  • The negative charges on ATP, ADP and DNA are counterbalanced by cations, usually magnesium.