# Explaining the Result of Adding AgNO3 to Test Tube #6

• General_Sax
In summary, the conversation discusses an equation involving COCL4 and H2O that results in a color change from blue to pink. The solution in test tube #6 turns pink, indicating a shift to the products. A precipitate is also formed. The conversation then delves into an explanation for this occurrence, discussing the solubility of Ag+ and Cl- and how the equilibrium can be shifted to the right. The final equation presented is CoCl42- + 6HOH + 4AgNO3(s) <=> Co(HOH)62+ + 4AgCl(s) + 4NO3- + energy, although it is noted that this equation may not be entirely correct.
General_Sax

## Homework Statement

COCL4 + 6H2 <=> Co(H20) +4CL

blue <=> pink

Question: Add a very small amount of AgNO3 to test tube #6. Stopper the test tube and shake.

The solution in test tube turned pink, so I interpreted that as a shift to the products. Also, a precipitate (proper term? a solid was present...) formed.

## The Attempt at a Solution

Now I have to offer an explanation for why this occurred. It seems as though the Ag+ is slightly soluble in Cl-, and the Cl is found on the product side, so was the Cl consumed somehow and thus produced CoCl42-?

To me that doesn't seem reasonable.

EDIT: I somehow thought myself into a circle, because CoCl42- wouldn't have been produced, for if it had the solution should have turned blue right? I'm fairly sure my explanation should hinge on the fact that Ag+is only slightly soluble with Cl-, but I don't want to go off on a tangent either, so if I'm horribly misguided please advise.

Last edited:
I'm using this thread as a sort of running journal. If that is unacceptable, for some reason, please do inform me.

New equation:

2AgNO3(s) + 6H2O(al) + 2CoCl4(al)2- <=> Co(h2O)6(al)2+ + 8Cl(al)- + Co(NO3)2 (al) + 2Ag (s) + energy

How many different ways can the equilibrium be shifted to the right? i.e. Removal of product, addition of reactant and removal of energy.

The charges on the new equation don't balance. Looks like more Co(H20)6 (al) 2+ will have to be produced, and if that holds true then I can explain the colour change.

None of the reaction you have written so far is correct.

What happens in the solution containing Ag+ and Cl-?

Borek said:
None of the reaction you have written so far is correct.

What happens in the solution containing Ag+ and Cl-?

CoCl42- + 6HOH + 4AgNO3(s) <=> Co(HOH)62+ + 4AgCl(s) + 4NO3- + energy

Is this equation correct?

Much better, but not necesarilly correct.

AgNO3 is well soluble. And no need to put some fancy looking dihydrogen monoxide HOH in the equation

Doesn't HOH = H2O? I just found it easier to type HOH, so I did. Thanks for the help.

## What is the purpose of adding AgNO3 to Test Tube #6?

The purpose of adding AgNO3 to Test Tube #6 is to test for the presence of chloride ions. Silver nitrate (AgNO3) reacts with chloride ions to form a white precipitate of silver chloride (AgCl).

## What does a positive result of adding AgNO3 to Test Tube #6 indicate?

A positive result of adding AgNO3 to Test Tube #6 indicates the presence of chloride ions. The formation of a white precipitate of silver chloride confirms the presence of chloride ions in the substance being tested.

## What does a negative result of adding AgNO3 to Test Tube #6 indicate?

A negative result of adding AgNO3 to Test Tube #6 indicates the absence of chloride ions. If no white precipitate is formed, it means that there are no chloride ions present in the substance being tested.

## What other substances could potentially interfere with the result of adding AgNO3 to Test Tube #6?

Other substances that could potentially interfere with the result of adding AgNO3 to Test Tube #6 include sulfide ions and bromide ions. These ions can also react with silver nitrate to form white precipitates, which may lead to a false positive result for chloride ions.

## What precautions should be taken when interpreting the result of adding AgNO3 to Test Tube #6?

When interpreting the result of adding AgNO3 to Test Tube #6, it is important to consider the potential for interference from other substances. It is also important to carefully observe the formation of the precipitate and compare it to known reactions to accurately identify the presence or absence of chloride ions.

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