Removing rust

Removing rust

Pencil and paperOnline interactive
Overview
Connecting to the Curriculum
Marking Student Responses
Further Resources
This task is about acid reactions.

Question 1Change answer

a)  Petra wanted to test how an acidic solution cleans rusty nails.
     First she had to be sure the solution she was using was acidic.
     What could she do to test if a solution is acidic or not? 

Question 1Change answer

b) She weighed several rusty nails and put them into an acid. She left them overnight, removed them from the acid, and then re-weighed the nails.
 
    How would the mass of each nail have changed?
Explain your answer.

Question 1Change answer

c)  Petra described the reaction as a neutralisation reaction. What does this mean?
Level:
5
Curriculum info: 
Science, Knowledge, Material World
Keywords: 
changes, pH scale, acids, acid-base reactions, indicators, neutralisation
Description of task: 
Explain how to test if a solution is an acid or not, and describe and explain what happens if rusty nails are put in an acid. Assessment focus: acid reactions.
Answers/responses: 
    Y9 (04/1997) Y10 (04/1997)
a) Any 1 of:

  • litmus [blue litmus paper turns red]
  • universal indicator [universal indicator turns orange or red]
  • carbonate [a carbonate will fizz]
  • Zn/Mg (reactive metal) [a metal will produce a salt and hydrogen gas]
 very difficult difficult
b) i) Decreased.
ii) The rust has reacted with the acid forming new products which are soluble/dissolved.
[NOTE: iron will react too and products are soluble.]		 difficult
moderate		 moderate
moderate
c) Acid + base = neutralisation reaction (salt + water are the products of this reaction). - -