### All GRE Subject Test: Chemistry Resources

## Example Questions

### Example Question #4 : Solubility And Equilibrium

Consider the following balanced equation for the solubility of barium hydroxide in an aqueous solution.

What is the solubility of barium hydroxide?

**Possible Answers:**

**Correct answer:**

In order to solve for the solubility of barium hydroxide, we need to establish an ICE table for the reaction.

I. Initially, there are no barium ions or hydroxide ions in the solution, so we can call their concentrations zero at the beginning of the reaction.

C. For every molecule of dissolved barium hydroxide, there will be one ion of barium and two ions of hydroxide. As a result, the increases in each ion can be designated and , respectively.

E. Finally, we plug these values into the equilibrium expression and set it equal to the solubility product constant.

### Example Question #1 : Solubility And Precipitation

Write the solubility product, , for .

**Possible Answers:**

**Correct answer:**

The solubility product constant () is an expression that describes the extent to which a compound is soluble in an aqueous solution. It describes the equilibrium between a solid and its constituent ions in a solution. The equilibrium constant for can be written as:

The denominator represents solid barium sulfate which is considered a constant. When the equation is rearranged, it becomes:

The product, , can be considered a constant expression called the solubility product constant () and the equation can be written in the form:

### Example Question #2 : Solubility And Precipitation

Write the solubility product, , for .

**Possible Answers:**

**Correct answer:**

The solubility product constant () is an expression that describes the extent to which a compound is soluble in an aqueous solution. It describes the equilibrium between a solid and its constituent ions in a solution. The equilibrium constant for can be written as:

The denominator represents solid barium sulfate which is considered a constant. When the equation is rearranged, it becomes:

The product, , can be considered a constant expression called the solubility product constant () and the equation can be written in the form:

### Example Question #3 : Solubility And Precipitation

Write the expression for the following equilibria:

**Possible Answers:**

None of these

**Correct answer:**

The solubility product constant () is an expression that describes the extent to which a compound is soluble in an aqueous solution. It describes the equilibrium between a solid and its constituent ions in a solution.The equilibrium between undissolved and its ions dissolved in solution is:

The equilibrium constant for can be written as:

The denominator represents solid barium sulfate which is considered a constant. When the equation is rearranged, it becomes:

The product, , can be considered a constant expression called the solubility product constant () and the equation can be written in the form:

### Example Question #4 : Solubility And Precipitation

Considering that for the equilibrium reaction:

What would be the concentration for a solution buffered at a pH of 8.5?

**Possible Answers:**

**Correct answer:**

The pH of the solution is , therefore the pOH would be considering the relationship:

Therefore ^{ }based on the equation

The solubility product expression for is :

By inserting the knowns in to the expression, gives:

Rearrange this equation

### Example Question #5 : Solubility And Precipitation

The K_{sp} of is . What is the molar solubility of _{ }in water?

**Possible Answers:**

**Correct answer:**

The equation for the dissolution of in water is below:

The K_{sp }for the above equation is:

Due to the solubility of _{ }of in water, the concentration of and ^{-} should be equal:

Plug into the K_{sp} equation:

Therefore:

The solubility of in water is

### Example Question #6 : Solubility And Precipitation

The K_{sp} of is . What is the molar solubility of in_{ }water?

**Possible Answers:**

**Correct answer:**

The equation for the dissolution of in water is below:

The K_{sp} for the above equation is:

Due to the solubility of of in water, the concentration of and should be equal:

Plugging X into the K_{sp} equation gives:

Therefore:

The solubility of CuBr in water is

### Example Question #7 : Solubility And Precipitation

Which salt is insoluble in water?

**Possible Answers:**

**Correct answer:**

Solubility rules must be followed for substances in aqueous media. Below are some of the solubility rules and they must be followed in the order given. For example, rule 1 should have precedence over rule 2.

1. All alkali metal and compounds are soluble.

2. Nitrate , perchlorate , chlorate, , and acetate salts are soluble.

3. Silver, lead, and mercury salts are insoluble.

Thus, we see that silver chloride is insoluble due to rule 3.

### Example Question #8 : Solubility And Precipitation

The of is . What is the molar solubility of in water?

**Possible Answers:**

**Correct answer:**

The equation for the dissolution of in water is:

The for the above equation is:

Due to the molar ratios of the species of , the concentration of and should be equal when dissolved:

Plugging into the equation gives:

Therefore, the solubility of in water is

### Example Question #9 : Solubility And Precipitation

Calculate the molar solubility of with if enough is added to raise the pH of the solution to pH 12.

**Possible Answers:**

**Correct answer:**

The equation for the dissolution of in water is:

The for the above equation is:

Due to the solubility of in water, the concentration of can be set to:

Therefore the concentration of should be double that of :

The solution was adjusted to pH 12 using , therefore:

Using an ICE table to process the data:

Plugging these variables into the equation gives:

Therefore, the equation can be approximated to:

Therefore, the solubility of in water is .

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