Unit 4 Test review - Solutions and Solubility Flashcards
What is a solute?
○ a substance that dissolves in a solvent
What is a solvent?
○ The substance that dissolves solutes
○ The particles of a solute
○ and is usually the substance in a solution present in the
greatest amount
What are the different levels of solubility?
○ 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.
Define the term solution
○ A homogenous mixture of 2 or more substances
In a solution…
○ The particles of a solute
○ Are evenly distributed throughout the solvent
resulting in a solution that is considered
homogeneous
Define homogenous
○ Uniform in composition
○ Equally distributed throughout
What do we call solutions where the solvent is water?
○ Aqueous
Different substances dissolve…
○ more readily in a solvent
○ OR in different amounts in a solvent
What are the three types of variables taken into consideration when conducting an experiment? Explain each
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
What does concentrated mean?
○ A high ratio of solute to solution
What does dilute mean?
○ a low ratio of solute to solution
What are the 4 types of ways to calculate concentration? What is the formula for each of them?
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
What do the symbols for molar concentration mean?
○ mo = amount of solute (mol)
○ vo = amount of solution (L)
○ co = concentration of solution (mol/L)
What are the two ways to prepare solutions?
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
What is a stock solution?
○ a concentrated solution that is diluted for use
What is solubility?
○ The MAX amount of a substance that can dissolve in A given
amount of a solvent at a specific temperature
What is the formula for calculating the concentration of a diluted solution? What do these variables mean?
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)
What is the key difference between percent concentration and molar concentration?
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
What are simple general steps to prepare a solution dissolving a solid solute?
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
What is a standard solution?
A solution with an accurate/known concentration
What is a simple procedure to dilute a stock solution?
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
