All GRE Subject Test: Chemistry Resources
Example Questions
Example Question #1 : Gravimetric Analysis
Household vinegar contains the organic compound acetic acid with chemical formula, . If a vinegar sample contains of acetic acid, calculate the percent (mass/mass) of the in the vinegar sample.
Density of vinegar is the following:
Convert the moles of to grams:
To calculate the percentage of in the vinegar we need to use the following formula:
Therefore,
Example Question #1 : Analyzing Solids
Consider the following balanced equation for the solubility of barium hydroxide in an aqueous solution.
What is the solubility of barium hydroxide?
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 .
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 #1 : Solubility And Precipitation
Write the solubility product, , for .
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 expression for the following equilibria:
None of these
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 #45 : Analytical Chemistry
Considering that for the equilibrium reaction:
What would be the concentration for a solution buffered at a pH of 8.5?
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 #43 : Analytical Chemistry
The Ksp of is . What is the molar solubility of in water?
The equation for the dissolution of in water is below:
The Ksp for the above equation is:
Due to the solubility of of in water, the concentration of and - should be equal:
Plug into the Ksp equation:
Therefore:
The solubility of in water is
Example Question #44 : Analytical Chemistry
The Ksp of is . What is the molar solubility of in water?
The equation for the dissolution of in water is below:
The Ksp for the above equation is:
Due to the solubility of of in water, the concentration of and should be equal:
Plugging X into the Ksp equation gives:
Therefore:
The solubility of CuBr in water is
Example Question #2 : Solubility And Precipitation
Which salt is insoluble in water?
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 #1 : Analyzing Solids
The of is . What is the molar solubility of in water?
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
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