Question

Solution Investigation Question: What are some of the key characteristics of unknown sample of an aqueous solution containing an ionic compound?

Specific questions: 1. Given that the cation is from Group 1A, what is the identity of the group 1A metal ion in your solution?

2. Given that the ionic compound contains either chloride or hydroxide, how can you determine which? (Two pieces of evidence are required and one must be related to solubility rules)

3. What is the concentration of your solution? (Your unknown sample is known to be about 1 M, but you need to determine the concentration to 3 significant figures using titration. You should plan ahead so that you know approximately what volume of your sample you will need in order to use approximately 25 mL of 0.100 M sulfuric acid for the titration).

Answer 1

Answer 2.When two solutions are mixed, a compound formed from a cation in one solution and an anion in the second solution will precipitate if its concentration is higher than its solubility (see Section 4.4 of Silberberg). Therefore, the solubility test can be conducted by mixing a few drops from two different solutions and noting whether a precipitate forms.(The formation of a solid precipitate will be evident due to the increased turbidity of the mixture).For qualitative analysis, often only general trends in solubility need to be known. These trends can be summarized by a set of relatively simple rules, often referred to as “the solubility rules”

So if the anion is Cl-, Br-, I- then cation will be + Any, except Ag+, Pb2+, Hg2+,Cu+and the compound will be Soluble

Or if the anion is OH– ,S2- then cation will be + Any, except alkali metal ions, NH4+, Sr2+. , Ca2+ , Ba2+and the compound will be Insoluble

Answer.3 Assuming if we can burn away the water and just leave the material remaining we can easily find the unknown.

This requires both step 2 and 3 to be completed.

The first thing is we know the concentration. So since we know the concentration we can get a specific amount of moles.

Lets just assume for the sake of this that you have .1 mol of the solution.

We also know if it is a hydroxide or chloride form number 2.

Take a look at this and what do you have.
Moles you have of product.
Weight of half of the compound.
So all you need to do from here is weigh the solution.

Mass/Mols = molar mass 1
molar mass = Molar mass of the other half
Molar mass of the other half gives us the molar mass of the element.

Answer 2.When two solutions are mixed, a compound formed from a cation in one solution and an anion in the second solution will precipitate if its concentration is higher than its solubility (see Section 4.4 of Silberberg). Therefore, the solubility test can be conducted by mixing a few drops from two different solutions and noting whether a precipitate forms.(The formation of a solid precipitate will be evident due to the increased turbidity of the mixture).For qualitative analysis, often only general trends in solubility need to be known. These trends can be summarized by a set of relatively simple rules, often referred to as “the solubility rules”

So if the anion is Cl-, Br-, I- then cation will be + Any, except Ag+, Pb2+, Hg2+,Cu+and the compound will be Soluble

Or if the anion is OH– ,S2- then cation will be + Any, except alkali metal ions, NH4+, Sr2+. , Ca2+ , Ba2+and the compound will be Insoluble

Answer.3 Assuming if we can burn away the water and just leave the material remaining we can easily find the unknown.

This requires both step 2 and 3 to be completed.

The first thing is we know the concentration. So since we know the concentration we can get a specific amount of moles.

Lets just assume for the sake of this that you have .1 mol of the solution.

We also know if it is a hydroxide or chloride form number 2.

Take a look at this and what do you have.
Moles you have of product.
Weight of half of the compound.
So all you need to do from here is weigh the solution.

Mass/Mols = molar mass 1
molar mass = Molar mass of the other half
Molar mass of the other half gives us the molar mass of the element.

Answer 2.When two solutions are mixed, a compound formed from a cation in one solution and an anion in the second solution will precipitate if its concentration is higher than its solubility (see Section 4.4 of Silberberg). Therefore, the solubility test can be conducted by mixing a few drops from two different solutions and noting whether a precipitate forms.(The formation of a solid precipitate will be evident due to the increased turbidity of the mixture).For qualitative analysis, often only general trends in solubility need to be known. These trends can be summarized by a set of relatively simple rules, often referred to as “the solubility rules”

So if the anion is Cl-, Br-, I- then cation will be + Any, except Ag+, Pb2+, Hg2+,Cu+and the compound will be Soluble

Or if the anion is OH– ,S2- then cation will be + Any, except alkali metal ions, NH4+, Sr2+. , Ca2+ , Ba2+and the compound will be Insoluble

Answer.3 Assuming if we can burn away the water and just leave the material remaining we can easily find the unknown.

This requires both step 2 and 3 to be completed.

The first thing is we know the concentration. So since we know the concentration we can get a specific amount of moles.

Lets just assume for the sake of this that you have .1 mol of the solution.

We also know if it is a hydroxide or chloride form number 2.

Take a look at this and what do you have.
Moles you have of product.
Weight of half of the compound.
So all you need to do from here is weigh the solution.

Mass/Mols = molar mass 1
molar mass = Molar mass of the other half
Molar mass of the other half gives us the molar mass of the element.

Answer 2.When two solutions are mixed, a compound formed from a cation in one solution and an anion in the second solution will precipitate if its concentration is higher than its solubility (see Section 4.4 of Silberberg). Therefore, the solubility test can be conducted by mixing a few drops from two different solutions and noting whether a precipitate forms.(The formation of a solid precipitate will be evident due to the increased turbidity of the mixture).For qualitative analysis, often only general trends in solubility need to be known. These trends can be summarized by a set of relatively simple rules, often referred to as “the solubility rules”

So if the anion is Cl-, Br-, I- then cation will be + Any, except Ag+, Pb2+, Hg2+,Cu+and the compound will be Soluble

Or if the anion is OH– ,S2- then cation will be + Any, except alkali metal ions, NH4+, Sr2+. , Ca2+ , Ba2+and the compound will be Insoluble

Answer.3 Assuming if we can burn away the water and just leave the material remaining we can easily find the unknown.

This requires both step 2 and 3 to be completed.

The first thing is we know the concentration. So since we know the concentration we can get a specific amount of moles.

Lets just assume for the sake of this that you have .1 mol of the solution.

We also know if it is a hydroxide or chloride form number 2.

Take a look at this and what do you have.
Moles you have of product.
Weight of half of the compound.
So all you need to do from here is weigh the solution.

Mass/Mols = molar mass 1
molar mass = Molar mass of the other half
Molar mass of the other half gives us the molar mass of the element.