SOLUTIONS CHEMISTRY Flashcards
What is a solution? What are solutions composed of?
A homogenous mixture of 2 or more substances
In a homogenous mixture the substances included are uniform
Solutions are composed of SOLUTES and SOLVENTS
What is a solute?
The substance being dissolved
Can be liquid, solid, or gas
Typically the less abundant component of the solution
What is a solvent?
The substance that dissolves the solute
Can be liquid, solid, or gas
Typically the substance that is in greater abundance
What is an aqueous solution?
A solution created by dissolving a solute in water
Solutions can be classified as…
Saturated, unsaturated, supersaturated
What is a saturated solution?
The solution contains the maximum amount of solute for the solvent at a specific temperature
What is an unsaturated solution?
The solution contains less than the maximum amount of solute for the solvent at a specific temperature
What is a supersaturated solution?
The solution can hold more solute than is present in the saturated solution
Heat is required for more solute to be dissolved
Will form crystals (crystallize)
What is solvation?
The interaction between solute and solvent particles; the attaching of solute to solvent particles is called solvation
Solvation occurs at the surface of a solid
What type of molecule is water? What does this mean?
Water is a polar molecule meaning…
It is covalently bonded with positive and negative ends
Since water is polar it interacts with ionic solids (polar molecules).
NaCl is an example of an ionic solid, the positive Na+ would bond with the negative oxygen in H2O
What is dissociation?
Dissociation is the process of crystal decomposition into component ions
Dissociation is the separation of ions from each other
Dissociation can be expressed by the following formula:
NaCl (s) —H2O—> Na+(aq) + Cl-(aq)
What is Molarity (M)?
Mol/L (# of moles of a substance dissolved per litre of solution)
a.k.a. How much solute and solvent are present
Also referred to as the concentration of a solution. Shown with [ ]
What are dilutions?
Changing the concentration of a substance to lower the molarity
More solvent is added to dilute a solution
Solutions in a lab are of high concentration and can be diluted to any desired concentration
Dilution equation
(M1)(V1) = (M2)(V2)
Initial higher concentration -> final diluted concentration
Note: know how to do the following equations
Moles, Molarity, etc.,
dilution, ion concentration in mixed solutions, precipitation reactions, solubility questions.
What factors affect the role of dissolving?
- Heating
Temperature increases the motion of the molecules
which allows them to collide with water more often
This increases the rate of dissolving - Stirring
By stirring, we are bringing fresh solvent into contact with the solute
This increases the rate of dissolving - Particle Size
Increasing the surface area (crushing) means that there is a greater probability that the molecules will collide
This increases the rate of dissolving
What factors affect solubility?
1.
Nature of solute and solvent
Polar or nonpolar Like dissolves like
2. Temperature
Solubility generally increases as temperature increases
(solid solute)
Solubility of solutes vs temperature can be graphed. The
3. Pressure
No effect for solid and liquid solutes
For gas solutes, as pressure increases solubility increases and vice versa
curves that are generated are called solubility curves
For all gases, solubility decreases as temperature increases
Spectator ions and net equation
The ionic equation shows all the ions in the reaction
Some of the ions in the equation take no part in the reaction and are not involved in the chemical change
These ions are called spectator ions and they can be cancelled off
The resulting equation is called the Net Ionic Equation
