chemistry help please

This question is about the identification of ions in unknown solutions.
A student completes a number of test-tube reactions on solutions A, B and C.
Table 2 shows the student’s observations.
Table 2
Test 1 Test 2 Test 3
Add H2SO4(aq) Warm with NaOH(aq) Add acidified AgNO3(aq)
A white precipitate, no visible change no visible change.
B effervescence, a gas is formed that turns, damp red litmus blue, effervescence.
C no visible change, no visible change, off-white precipitate

Suggest the identity of the positive ion in solution A.

Give the simplest ionic equation for the formation of the white precipitate in
Test 1 for solution A.

Identity of positive ion in A :
Ionic equation:

Different gases are formed when solution B reacts in Test 1 and in Test 2.
Suggest the identity of each gas.
Give the simplest ionic equation for the formation of the gas in Test 2.

Gas formed in Test 1:
Gas formed in Test 2:
Ionic equation for the formation of the gas in Test 2:

The student thinks that solution C contains either chloride ions or bromide ions.
Describe a further test, or tests, to show whether solution C contains chloride or
bromide ions.

Reply 1

bl0bf1sh

15

what have you got so far?

Reply 2

GCM42

11

Original post by nesaa

This question is about the identification of ions in unknown solutions.
A student completes a number of test-tube reactions on solutions A, B and C.
Table 2 shows the student’s observations.
Table 2
Test 1 Test 2 Test 3
Add H2SO4(aq) Warm with NaOH(aq) Add acidified AgNO3(aq)
A white precipitate, no visible change no visible change.
B effervescence, a gas is formed that turns, damp red litmus blue, effervescence.
C no visible change, no visible change, off-white precipitate

Suggest the identity of the positive ion in solution A.

Give the simplest ionic equation for the formation of the white precipitate in
Test 1 for solution A.

Identity of positive ion in A :
Ionic equation:

Different gases are formed when solution B reacts in Test 1 and in Test 2.
Suggest the identity of each gas.
Give the simplest ionic equation for the formation of the gas in Test 2.

Gas formed in Test 1:
Gas formed in Test 2:
Ionic equation for the formation of the gas in Test 2:

The student thinks that solution C contains either chloride ions or bromide ions.
Describe a further test, or tests, to show whether solution C contains chloride or
bromide ions.

The addition of H2SO4 is used to test for barium ions as barium sulphate is formed, which is a white precipitate.

The addition of NaOH is used to test for ammonia (if ammonia is present, a pungent gas that turns damp red litmus paper will form)

The addition of acidified silver nitrate (acidification is from nitric acid) is used to test for halide ions. A further test is to use varying concentrations of ammonia to form an ammoniacal silver complex (silver chloride dissolves in dilute and conc. NH3, whereas silver bromide only dissolves in conc. NH3)