All High School Chemistry Resources
Example Questions
Example Question #6 : Concentration And Units
Which of the following aqueous solutions is the most concentrated?
All of these solutions have the same concentration.
In order to answer this question, it helps to know that 1 kilogram of water is equal to 1 liter of water, due to its density. Two of the above options refer to a 1m solution of hydrochloric acid. The other is a 1M solution.
All three of the options have the same amount of hydrochloric acid (one mole). For molarity, the hydrochloric acid is diluted with water until one liter of solution is created. For molality, one mole of HCl is added to one kilogram of water. Since one kilogram of water is one liter, this becomes the same concentration.
One a very small level, the 1M HCl solution will be slightly more concentrated. Creating a molal solution does not take into account the volume of the solute. If, for example, 100 cubic centimeters of HCl were added to one kilogram of water, the resulting volume would be more than one liter, making the concentration slightly less than 1M. This discrepancy is usually not accounted for in basic chemistry, but you should be familiar with the concept.
Example Question #7 : Concentration And Units
What is the molality of a solution created by mixing 4.3g into 43g of water?
Cannot be determined
Molality can be defined:
It is slightly different from Molarity and has different uses.
Example Question #1 : Titrations
How much solid NaOH must be dissolved to make 740mL of a 0.32M solution?
9.47g
4.26g
9.47 * 102g
The sodium hydroxide will boil off with the water
12.8g
9.47g
This problem can be solved by stoichiometry. Remember that 0.32M gives us the moles of NaOH per liter, and solve for the number of moles per 0.740L.
Example Question #1 : Titrations
Find the mass of in 10L of water if it is a 2m solution.
Molality is grams of solute per kilogram of solvent.
Water has a density of one gram per mililiter, so one liter of water equal to one kilogram. If we have a 2m solution, that means we have two moles of per kilogram of water.
has a molecular weight of .
This gives us of .
Example Question #1 : Titrations
10mL of a solution of of unknown concentration mixed with 34mL of produced a solution with a pH of 7. What is the concentration of the solution?
None of these
For this question use the following formula:
is the number of acidic hydrogens on the acid, is the molarity of the acid, is the volume of the acid, is the number of basic hydroxides on the base, is the molarity of the base, is the volume of the base
Rearrange the equation for the molarity of the base:
Plug in known values and solve.
Example Question #472 : High School Chemistry
30mL of a solution of of unknown concentration mixed with 19mL of produced a solution with a pH of 7. What is the concentration of the solution?
None of these
For this question use the following formula:
is the number of acidic hydrogens on the acid, is the molarity of the acid, is the volume of the acid, is the number of basic hydroxides on the base, is the molarity of the base, is the volume of the base
Rearrange the equation for the molarity of the base:
Plug in known values and solve.
Example Question #481 : High School Chemistry
29mL of a solution of is mixed with 65mL of an solution of unknown concentration produced a solution with a pH of 7. What is the concentration of the solution?
None of these
For this question use the following formula:
is the number of acidic hydrogens on the acid, is the molarity of the acid, is the volume of the acid, is the number of basic hydroxides on the base, is the molarity of the base, is the volume of the base
Rearrange the equation for the molarity of the acid:
Plug in known values and solve.
Example Question #11 : Titrations
39mL of a solution of is mixed with 24mL of an solution of unknown concentration produced a solution with a pH of 7. What is the concentration of the solution?
None of these
For this question use the following formula:
is the number of acidic hydrogens on the acid, is the molarity of the acid, is the volume of the acid, is the number of basic hydroxides on the base, is the molarity of the base, is the volume of the base
Rearrange the equation for the molarity of the acid:
Plug in known values and solve.
Example Question #482 : High School Chemistry
None of these
For this question use the following formula:
is the number of acidic hydrogens on the acid, is the molarity of the acid, is the volume of the acid, is the number of basic hydroxides on the base, is the molarity of the base, is the volume of the base
Rearrange the equation for the molarity of the acid:
Plug in known values and solve.
Example Question #12 : Titrations
None of these
For this question use the following formula:
is the number of acidic hydrogens on the acid, is the molarity of the acid, is the volume of the acid, is the number of basic hydroxides on the base, is the molarity of the base, is the volume of the base
Rearrange the equation for the molarity of the acid:
Plug in known values and solve.