A green powder, G, is used as a pigment in paint.
A student does four tests on G.
Test 1: When G is heated strongly, it turns into a black solid. The gas given off turns limewater milky.
Test 2: The black solid dissolves in warm dilute sulfuric acid to make a blue solution.
Test 3: Sodium hydroxide solution is added to the blue solution. A blue precipitate forms.
Test 4: A flame test on G gives a green flame.
Identify the gas given off in Test 1.
Identify the metal ion in G.
Give two pieces of evidence from the tests.
G is a compound of one metal and one negative ion.
Name G and write the balanced symbol equation for the reaction in Test 1.
Write the balanced symbol equation for the reaction of the black solid with dilute sulfuric acid in Test 2.
The student heats 2.47 g of G until there is no further change. The mass of black solid left is 1.59 g.
Show that these masses are consistent with your answer to (c).
Relative atomic masses (Ar): C = 12.0, Cu = 63.5, O = 16.0
The student says:
"Test 1 alone proves that G is a carbonate."
Evaluate the student's statement.
52 exam-style questions on OCR GCSE Chemistry 4.2 Identifying the products of chemical reactions, covering 4.2.1 Tests to identify gases, 4.2.2 Tests for aqueous ions and flame tests, and 4.2.3 Instrumental methods of analysis. Each one has a worked solution and a mark scheme showing where the marks go.