CHEMICAL ANION ADDITION OF AgNO3 ADDITION OF HCl NaBr BROMIDCARBONATEE CLOUDY NO
ID: 1018865 • Letter: C
Question
CHEMICAL
ANION
ADDITION OF AgNO3
ADDITION OF HCl
NaBr
BROMIDCARBONATEE
CLOUDY
NOTHING
Na2CO3
CHLORIDE
CLOUDY
BUBBLES
NaCl
IODIDE
CLOUDY
THIN CLOUD
Nal
SULFATE
CLOUDY
THICK WHITE COLOR
Na2SO4
SULFIDE
NOTHING
THIN WHITE
Na2S
YELLOW CLOUD
BROWN CLUMPS
UNKNOWN 103
WHITE CLOUD
THICK WHITE
UNKNOWN 104
BLACK CLOUD
BROWN CLOUD
What was the identity of the anion in Unknown #103? Explain how you used the observations recorded in Data Table 1 to reach this conclusion.
What was the identity of the anion in Unknown #104? Explain how you used the observations recorded in Data Table 1 to reach this conclusion.
Write the chemical equation for ionic reaction between Na2 S and AgNO3 .
Write the chemical equation for ionic reaction between NaBr and AgNO3 .
Use your results and observations in Data Table 1 to create a flow chart for identification of unknown anions, using the AgNO3 and HCl confirmation tests. Insert the flow chart below
CHEMICAL
CATION
FLAME OBSERVATIONS
Kl
POTASSIUM
YELLOW
CaCl2
CALCIUM
RED
LiOH
LITHIUM
PURPLE
NaCl
SODIUM
ORANGE
Cu(NO3)2
COPPER
PURPLE RED AND GREEN
UNKNOWN 105
GREEN
UNKNOWN 106
ORANGE
UNKNOWN 107
NO CHANGE
CHEMICAL
CATION
ANION TEST OBESERVATIONS
ANION
COMPLETE CHEMICAL NAME
105
106
107
A. What was the identity of the cation in Unknown #105? Explain how you used the observations
recorded in Data Table 1 to reach this conclusion.
B. Use your results and observations in Data Tables 1, 2, and 3, to create a flow chart for the
identification of an unknown (both an unknown anion and cation), using the AgNO3
and HCl
confirmation tests and the cation flame tests.
C. If you were asked to confirm the identity of an unknown chemical as lithium sulfide (Li2
S),
describe the tests that you would use to confirm the identity. Use your results in both Exercise
1 and Exercise 2 to describe the observations in both the cation and anion tests that would
allow the unknown to be confirmed as lithium sulfide.
CHEMICAL
ANION
ADDITION OF AgNO3
ADDITION OF HCl
NaBr
BROMIDCARBONATEE
CLOUDY
NOTHING
Na2CO3
CHLORIDE
CLOUDY
BUBBLES
NaCl
IODIDE
CLOUDY
THIN CLOUD
Nal
SULFATE
CLOUDY
THICK WHITE COLOR
Na2SO4
SULFIDE
NOTHING
THIN WHITE
Na2S
YELLOW CLOUD
BROWN CLUMPS
UNKNOWN 103
WHITE CLOUD
THICK WHITE
UNKNOWN 104
BLACK CLOUD
BROWN CLOUD
Explanation / Answer
Unknown-103:
Addition of AgNO3 to this solution gives white cloudy and then turns into thick white on addition of HCl.
From table: NaI solution gives a white cloudy on addition of AgNO3 solution and turns into thick white on addition of HCl.
So, the anion in the unknown-103 solution is iodide (I- ).
Unknown-104:
This solution gives black cloud on addition of AgNO3 and Brown cloud on addition of HCl.
From table: Na2S can only gives yellow cloud on addition of AgNO3 and brown cloud on addition of HCl and no anion gives black cloud.
So, the anion in unknown-104 solution is sulfide (S2- ).
The net ionic equation between Na2S and AgNO3 is,
S2- (aq) + 2Ag+ (aq) -------> Ag2S(s)
The net ionic equation between NaBr and AgNO3 is,
Br- (aq) + Ag+ (aq) ------> AgBr(s)