Neutralisation
Q1.
The salt sodium hydrogen phosphate (Na2HPO4) is used as a softening agent in processed cheese.
 
          It can be made by reacting phosphoric acid (H3PO4) with an alkali.
(a)     Complete the name of an alkali that could react with phosphoric acid to make sodium hydrogen phosphate.
____________________ hydroxide
(1)
(b)     What is the name given to a reaction in which an acid reacts with an alkali to make a salt?
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(1)
(c)     How would the pH change when alkali is added to the phosphoric acid solution?
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(1)
(d)     What ions are present when any acid is dissolved in water?
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(1)
(e)     What ions are present when any alkali is dissolved in water?
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(1)
(f)      Write a chemical equation for the reaction which takes place between the ions you have named in (e) and (f).
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(1)
(Total 6 marks)
Q2.
The diagrams show what happens when an acid is added to an alkali.
 
(a)     What is present in the solution at stages 2 and 3 apart from universal indicator and water?
(i)      At stage 2 _____________________________________________________
(ii)     At stage 3 _____________________________________________________
(3)
(b)     Write an ionic equation to show how water is formed in this reaction and state the sources of the ions.
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(3)
(Total 6 marks)