Unit 8 Chemistry Review

Suspensions

Suspensions

Mixtures with large particles that settle at the bottom if not mixed, heterogeneously dispersed, can scatter light but not transparent.

Colloids

Mixtures with intermediate-sized particles, also called colloidal dispersion, where the solvent is dispersed in the dispersion medium as colloidal particles.

Tyndall effect

Scattering of light by colloidal particles in a transparent medium, seen in fog, indicating heterogeneity and inability to separate by filtration.

Solutions

Homogeneous mixtures where solute is dissolved in a solvent, not scattering light, with solute and solvent components.

Electrolytes

Substances that dissolve in water to conduct an electric current, including ionic solutions.

Miscible

Liquids that dissolve in each other.

Immiscible

Liquids that do not dissolve in each other.

Hydration

Solution with water as the solvent, where ions are surrounded by water molecules.

Factors affecting dissolving

• Increased surface area of the solution

• Stirring of solution

  • Speeds up process of dissolving

• Heating up a solvent

  • Increases rate in which particles bump into each others and dissolve

Solution equilibrium

A point of dissolving where the solution is at max saturation, and there is a set concentration of crystalized and saturation solution. The rate at which the crystals resolve or undergo dissolution and the rate at which the solute recrystallizes are the same so that the concentration of crystalized and saturation solution remains constant. 

Solubility

Maximum amount of solute that can dissolve in a solvent at a given temperature.

Concentration

Measure of solute amount in a given solvent.

Solution

Solvent + Solute

Percent volume

(Volume Solute/Volume Solution) x 100

Percent mass

(Mass Solute/Mass Solution) x 100

Molarity

Number of moles of solute in 1 liter of solution

Solvent in Moles/Liters of Solution

Properties of acids

• Aqueous solutions of acids have a sour taste

• Change color of acid-based indicators

  • Turns litmus paper red

• Some acids react with active metals and release hydrogen gas, H2

  • HCI + NaOH → NaCI + NaCI + H2O

• Acids conduct electrical current (electrolytes)

• pH less than 7

Properties of bases

Bitter taste, color change in indicators, feel slippery, react with acids to form salts and water, conduct electricity, pH > 7.

Arrhenius acid

Increases H+ concentration in water.

Arrhenius base

Increases OH- concentration in water.

Strong Acids

• Ionizes completely in an aqueous solution 

• Every ion in the solute completely breaks down in the solvent (water) and there are no more ions still undissociated 

Weak Acids

• Releases few hydrogen ions in aqueous solutions 

• Not all of the acid is dissociated 

• Some of the ions are still connected 

• Goes back and forth: weak not stable

• 

Bronsted-Lowry acid

Donates H+ ions.

Bronsted-Lowry base

Accepts H+ ions.

Conjugate Acid

Base that gained hydrogen → conjugate acid

Conjugate Base

Acid that lost Hydrogen → Conjugate Base

pH and pOH

Negative logarithm of H3O+ and OH- concentrations, respectively, with pH + pOH = 14.

Heterogeneous

Not evenly dispersed mixtures

Steps for Making Solutions (Ex. Preparing a 0.5000M Solution)

1. Start by calculating the mass of CuSo4 + 5H2) needed. Making a liter of this solution requires 0.5000 mol of solute. Convert the moles to mass by multiplying the molar mass of CuSO4 x 5H2O. The mass is calculated to be 124.8 g.  

2. Add some solvent to the solvent to dissolve it, and then pour it into a 1.0 L volumetric flask. 

3. Rinse the weighing beaker with more solvent to remove all the solute, and pour the rinse into the flask. Add water until the volume of the solutionnears the neck of the flask. 

4. Put the stopper in the flask, and swirl the solution thoroughly. 

5. Carefully fill the flask to the 1.0 L mark with water. Restopper the flask, and invert it at least 10 times to ensure complete mixing. 

6. The resulting solution has 0.5000 mol of solute dissolved in 1.000L of solution, which is a 0.5000 M concentration.

Binary Acid

Hydrogen and one of the more electronegative elements 

• Ex: Hydroflouric acid (HCI)

Oxyacid/Ternary Acid

Compound with hydrogen, oxygen, and a third element

• Ex: Chloric acid (HCIO)

Atmospheric Substances

Can be both acids and bases

• Ex. H2O

pH

potential hydrogen power

Calculating pH

pH = -log[ [H₃O⁺] or [H⁺]

OR 14 - pOH

pOH

potential hydroxide ion power

calculating pOH

pOH = -log [oh-]

OR 14 - pH