Acids, Bases and Solutions Chapter 7. Solutions. Notes 7-1 & 7-2. A homogeneous (uniform) mixture that contains a solvent and at least one solute Solvent = dissolves the other substances (Ex. water) Solute = dissolved by the solvent (Ex. salt)
Notes 7-1 & 7-2
A homogeneous (uniform) mixture that contains a solvent and at least one solute
Solvent = dissolves the other substances (Ex. water)
Solute = dissolved by the solvent (Ex. salt)
*In solutions, there is more solvent than solute.
Water is the universal solvent
It dissolves more solutes than any other solvents
Because its polar (slightly charged)
Life depends on water solutions
Water is the solvent in blood, saliva, sweat, tears
Solutions can be formed from any combination of solids, liquids, and gases.
Not all mixtures are solutions. Colloids and suspensions are mixtures that have different properties than solutions.
When a solution forms, particles of the solvent surround and separate the particles of the solute.
Ionic compounds, like salt (NaCl), are separated into individual ions
Covalent compounds (molecular compounds), like sugar, are separated into individual molecules
Ionic compounds in water conduct electrical current due to the charged ions present
Molecular compounds in water usually do not conduct electrical current
Solutes lower the freezing point of a solvent.
This is why salt is added to icy roads; it melts the ice and keeps it from refreezing thus making the roads less slippery.
Solutes raise the boiling point of a solvent.
This is why salt is added to water when boiling pasta; it makes the water hotter thus cooking the pasta faster.
Concentrated solutions have a lot of solute in the solvent
Dilute solutions have a small amount of solute in the solvent
Solubility is a measure of how much solute can dissolve in a solvent at a given temperature.
If solute continues to dissolve, the solution is unsaturated.
If no more solute will dissolve, the solution is saturated.
Which compound is the most soluble?
Pressure- increases solubility (soda can)
Solvent- some solvents and solutes are not compatible (oil and water), “like dissolves like”
Temperature- increases solubility (high temps when cooking)
Examples: Juice, Vitamin C, Vinegar, HCl
Examples: Ammonia (cleaners), baking soda, soap
Acids in Solutions
An acid produces Hydrogen ions (H+) in water
Acids in water solution separate into hydrogen ions (H+) and negative ions. In the case of hydrochloric acid, for example, hydrogen ions and chloride ions form:
High in Hydrogen Ions (H+), Low in Hydroxide Ions (OH-)
Low on the pH scale (pH0-pH7) *pH7= neutral
Bases in Solutions
A base produces hydroxide ions (OH-) in water
When bases dissolve in water, the positive ions and hydroxide ions separate. Look at what happens to sodium hydroxide in water:
Not all bases contain hydroxide ions. For example, the gas ammonia (NH3) does not. But in solution, ammonia is a base that reacts with water to form hydroxide ions.
Low in Hydrogen ions (H+), High in Hydroxide Ions (OH-)
High on pH scale (ph7-pH14)