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Worksheets4-3 WA1 Revision (C09 QA, C10 Redox)
Total questions: 35
Worksheet time: 46mins
Name a chemical other than aqueous sodium hydroxide that Chemists use to test for the presence of cation.
(a)
When Jason tests for the positive ion in a solution, he observes a blue precipitate.
What positive ion is present?
(a)
Chemical X is used to test for the cation. When X is added to a test tube containing an unknown solution, white precipitate is observed.
What is/are ions that could be present?
iron(II)
calcium ion
aluminium
Iron(II)
A few drops of chemical X is added to a solution containing Cu2+. What would be observed?
(a)
When a few drops of sodium hydroxide is added to a solution, green precipitate forms.
State the name of the green precipitate.
(a)
When a few drops of sodium hydroxide is added to a solution, red-brown forms.
State the name of the precipitate.
(a)
Describe the test for zinc ion.
Jayden suspects that calcium ion is present in a solution. When he puts a few drops of sodium hydroxide into the solution, white precipitate forms.
State the name of the precipitate.
(a)
When aqueous ammonia is added in excess to a solution containing Cu2+, the precipitate dissolves to form a (a)
State the name of this substance: Al3+
(a)
A student adds excess aqueous sodium hydroxide to a solution containing an unknown metal ion. A white precipitate forms but dissolves in excess sodium hydroxide, forming a colorless solution. Which of the following cations could be present in the solution?
(Select all that apply.)
Aluminum ion
Calcium ion
Zinc ion
Copper(II) ion
When aqueous sodium hydroxide is added to an unknown solution, a green precipitate forms. The precipitate turns reddish-brown on standing. The cation present is likely to be (a) ion.
A student tests for sulfate ions in a solution by adding (a) followed by (b) . The formation of a white precipitate confirms the presence of sulfate ions.
Match each cation with its characteristic observation when tested with aqueous sodium hydroxide.
Fe3+
Red brown ppt
Zn2+
White ppt dissolves in excess
Fe2+
Green ppt turns red brown on standing
Ca2+
White ppt insoluble in excess
A student is given a colorless solution and performs two tests:
- Adding aqueous sodium hydroxide produces a white precipitate that dissolves in excess.
- Adding aqueous ammonia produces a white precipitate that dissolves in excess.
Which cation is present in the solution?
(a)
A teacher asks students to confirm the presence of nitrate ions in an unknown solution.
Which steps should they follow?
Add aqueous sodium hydroxide
Add aluminum foil
Warm the mixture
Test for ammonia gas
Definition of redox reaction: Redox reaction is a reaction where both _____occur in the ___ chemical reaction.
oxidation and reduction, same
chemical and non-chemical, different
oxidation and reduction, different
oxidation and reduction, similar
Ca + 2HCl --> CaCl2 + H2
In the reaction, Ca is (a) because its oxidation state (b) from (c) to (d) .
In a reaction, Ba becomes BaCl2. The oxidation state of Ba (a) from (b) to (c)
State the initial colour of aqueous potassium iodide.
(a)
In a reaction, iron(II) ion becomes iron(III) ion. This is (a) because electron is (b) .
An oxidising agent (a) another substance while itself gets (b)
Group the chemicals into oxidising and reducing agents.
acidified potassium manganate(VII)
oxygen
hydrogen peroxide
carbon
carbon monoxide
sulfur dioxide
potassium iodide
When acidified potassium manganate(VII) is added to a chemical which is an reducing agent, the colour change would be from (a) to (b) .
When aqueous potassium iodide is added to a chemical which is an oxidising agent, the colour change would be from (a) to (b) .
State the colour of acidified potassium manganate(VII).
(a)
State the colour of aqueous potassium iodide.
(a)
State the oxidation state of O in O2.
(a)
State the oxidation state of magnesium in magnesium chloride (MgCl2).
(Hint: need to split MgCl2 into its ions.)
(a)
To test for the presence of a reducing agent, we need to use a (a) such as (b) .
To test for the presence of a oxidising agent, we need to use a (a) such as (b) .
State the oxidation state of iron(II) ion.
(a)
The oxidation state or number of a substance is similar as the (a) of the substance.
Classify the definitions of oxidation and reduction.
it gains oxygen
it loses hydrogen
it loses electron
its oxidation state increase
it loses oxygen
it gains hydrogen
it gains electron
its oxidation state decreases
When aqueous potassium iodide turns brown, it is because of the formation of (a)
