This is my last question for this month can some please answer question 1 and 2.

Question

This is my last question for this month can some please answer question 1 and 2.

Exercise 1: Qualitative Anion Tests

Data Table 1. Anion Confirmation Tests.

Chemical

Anion

Addition of AgNO3

Addition of HCl

NaBr

Bromide

It became white and cloudy

Still was white and cloudy

Na2CO3

Carbonate

Clear inside white and cloudy around the outside

Still white and cloudy but bubbles start to form

NaCl

Chloride

Turn white cloudy on bottom clear on top

Still white cloudy on bottom clear on top

NaI

Iodide

In the middle very dark and cloudy fades out lighter white around the middle

Became a little separate

Na2SO4

Sulfate

Clear

Became white and cloudy

Na2S

Sulfide

Turn a brown color in the middle but separated from the clear

The brown becomes more separate from the clear

Unknown #103

CO3^2-

White and cloudy

Small particles

Bubbles form white and cloudy

Unknown #104

S^2-

Turn brown color I the middle around clear

Some of the brown disappeared and become separate

Flow chart:

Solution containing: Br-, CO3^2-, Cl-, I-, SO4^2-, and S^2-

{AgBr(cloudy), Ag2CO3(cloudy), AglCloudy),Agl(very dark), Ag2S-(brown)}     {So4^2-}

{AgBr(cloudy), AgCl(cloudy), Agl(very cloudy), Ag2S(brown)}          {CO3^2-(decomposes to give CO2 gas)}

Data Table 2. Cation Flame Tests.

Chemical

Cation

Flame Observations

KI

Potassium

LIGHT PINK

CaCl2

Calcium

RED

LiOH

Lithium

FUSHA PINK

NaCl

Sodium

ORANGE

Cu(NO3)2

Copper

TEAL

Unknown #105

Copper

TEAL

Unknown #106

Potassium

LIGHT PINK

Unknown #107

Calcium

RED

Data Table 3. Complete Chemical Identification.

Chemical

Cation

Anion Test Observations

Anion

Complete Chemical Name and Formula

Unknown #105

Copper

with AgNO3: No chane

No3^2-

Copper(II) nitrate, Cu(NO3)2

Unknown #106

Potassium

with AgNO3: In the middle very dark and cloudy fades out lighter white the middle

I-

Potassium iodide, KI

Unknown #107

Calcium

With AgNO3: Turn white cloudy on the bottom on top

Cl-

Calcium chloride, CaCl2

Questions

1. 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.

2. If you were asked to confirm the identity of an unknown chemical as lithium sulfide (Li2S), 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

Bromide

It became white and cloudy

Still was white and cloudy

Na2CO3

Carbonate

Clear inside white and cloudy around the outside

Still white and cloudy but bubbles start to form

NaCl

Chloride

Turn white cloudy on bottom clear on top

Still white cloudy on bottom clear on top

NaI

Iodide

In the middle very dark and cloudy fades out lighter white around the middle

Became a little separate

Na2SO4

Sulfate

Clear

Became white and cloudy

Na2S

Sulfide

Turn a brown color in the middle but separated from the clear

The brown becomes more separate from the clear

Unknown #103

CO3^2-

White and cloudy

Small particles

Bubbles form white and cloudy

Unknown #104

S^2-

Turn brown color I the middle around clear

Some of the brown disappeared and become separate

Explanation / Answer

The solutions are as given below

1. This is practically adding AgNO3 and HCl solution to a mixture and observe the change : start from first, the one which gives change is the type of anion present. Sum all of it like,

With AgNO3 ------> does it became white and cloudy: Yes confirms Br-, Not absence of Br- -------> Does it became clear inside white and cloudy around the outside: Yes confirms CO3^2-, NOT absence of CO3^2- ------and then next.

Every place you will have two options one arrow going down for negative and other going on the side for +ve tests.

2. Li2S

Li can be identified by flame test : gives a fusha pink coloration to the flame

Sulfide S2- can be identified by AgNO3 test : turns a brown color in the middle but separated from the clear

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