Unit 4 Test review - Solutions and Solubility

Question 1

What is a solute?

Answer 1

○ a substance that dissolves in a solvent

Question 2

What is a solvent?

Answer 2

○ The substance that dissolves solutes
○ The particles of a solute
○ and is usually the substance in a solution present in the
greatest amount

Question 3

What are the different levels of solubility?

Answer 3

○ A solute is described as soluble if more than 1 g will dissolve in 100 mL of solvent. e.g. table salt is soluble in water.

○ A solute is described as partially soluble if it has a solubility
between 0.1 g and 1 g per 100 mL of solvent.

○ A solute is described as insoluble if less than 0.1 g of a solute
will dissolve in 100 mL of solvent.

Question 4

Define the term solution

Answer 4

○ A homogenous mixture of 2 or more substances

Question 5

In a solution…

Answer 5

○ The particles of a solute

○ Are evenly distributed throughout the solvent
resulting in a solution that is considered
homogeneous

Question 6

Define homogenous

Answer 6

○ Uniform in composition

○ Equally distributed throughout

Question 7

What do we call solutions where the solvent is water?

Answer 7

○ Aqueous

Question 8

Different substances dissolve…

Answer 8

○ more readily in a solvent

○ OR in different amounts in a solvent

Question 9

What are the three types of variables taken into consideration when conducting an experiment? Explain each

Answer 9

1) Independent variable - the variable that we change
2) Dependent variable - the variable we record
3) Controlled variable - the variable that we keep the same

Question 10

What does concentrated mean?

Answer 10

○ A high ratio of solute to solution

Question 11

What does dilute mean?

Answer 11

○ a low ratio of solute to solution

Question 12

What are the 4 types of ways to calculate concentration? What is the formula for each of them?

Answer 12

1) percent mass/mass:
% (m/m) = (mass of solute)/(mass of solution) ×100%
○ units are g

2) precent mass/volume
% (m/v) = (mass of solute)/(volume of solution) ×100%
○ units are g and mL

3) percent volume/volume
% (v/v) = (volume of solute)/(volume of solvent) x 100%
○ units are mL

4) Molar concentration
co = mo/vo
○ units are mol/L

Question 13

What do the symbols for molar concentration mean?

Answer 13

○ mo = amount of solute (mol)
○ vo = amount of solution (L)
○ co = concentration of solution (mol/L)

Question 14

What are the two ways to prepare solutions?

Answer 14

1) dissolve a measured mass of solid solute in water, then dilute
the solution to a known volume

2) dilute a stock solution by adding a known volume of water

Question 15

What is a stock solution?

Answer 15

○ a concentrated solution that is diluted for use

Question 16

What is solubility?

Answer 16

○ The MAX amount of a substance that can dissolve in A given
amount of a solvent at a specific temperature

Question 17

What is the formula for calculating the concentration of a diluted solution? What do these variables mean?

Answer 17

Formula: C1V1 = c2v2

C1 = concentration of stock solution 
V1 = volume of stock solution 
c2 = concentration of dilute solution (being prepared)
v1 = volume of dilute solution (being prepared)

Question 18

What is the key difference between percent concentration and molar concentration?

Answer 18

Percent concentration is the ratio of the amount of solute to solution. Molar concentration is a unit of concentration that specifically relates to the number of moles of a solute per liter of solution

Question 19

What are simple general steps to prepare a solution dissolving a solid solute?

Answer 19

1) measure a mass of solute (using a balance)
2) dissolve solute in water (in a volumetric flask)
3) mix the solution thoroughly
4) add water until the required volume on the flask
5) transfer the prepared solution to a clean, dry container

Question 20

What is a standard solution?

Answer 20

A solution with an accurate/known concentration

Question 21

What is a simple procedure to dilute a stock solution?

Answer 21

1) Pour the stock solution of a known volume into a volumetric flask
2) Use a volumetric pipette to transfer an aliquot of the solution into another container, allow the meniscus to reach the mark of the volumetric pipette required
3) Transfer the solution in the pipette to a new volumetric flask
4) Remove the pipette and dilute the transferred amount of the stock solution by adding an amount of solvent (water) until the exact required volume is reached on the volumetric flask