Unit 4 Chemistry Test

water and oil are non polar or polar

water is polar

oil is non polar

• SOLUTE:

• SOLVENT:

• SOLUTE: substance that is in the lesser quantity

• SOLVENT: substance that is in the greater quantity

*Note: solutions can contain multiple solutes

• CONCENTRATED SOLUTION:

• DILUTE SOLUTION:

• CONCENTRATED SOLUTION: high quantity of solute compared to the volume of the solution

• DILUTE SOLUTION: low quantity of solute compared to the volume of the solution

Solution:

Solution: a homogeneous mixture made when a solute dissolves in a solvent

• DISSOCIATION:

• HYDRATION:

• DISSOCIATION: the separation of individual ions from an ionic compound as it dissolves in H2O

• HYDRATION: the process in which ions are surrounded by water molecules

Single Displacement Reactions

Key idea
If the free element is higher on the activity series, the reaction happens.

Double Displacement Reactions

A reaction only occurs if a driving force is formed.

Driving forces include
a precipitate (solid)
a gas
water (neutralization)

Determining dipoles

The arrow points to the more electronegative atom

Increases going right

Atoms become more electronegative as you move across a period (left → right)

Increases going up

Atoms become more electronegative as you move up a group (bottom → top)

The most electronegative atoms are usually:

F, O, N, Cl

Polar or non polar

Uneven shape → usually polar

Symmetrical shape → usually nonpolar

Intermolecular forces

H with N/O/F → hydrogen bonding

Polar (no H-bond) → dipole–dipole

Nonpolar → London dispersion

Like dissolves like 

• Polar substances dissolve in polar substances

• Nonpolar substances dissolve in nonpolar substances

• Ionic compounds usually dissolve in polar substances (especially water)

Dissolving

• Water molecules bump into solute

• Water surrounds solute

• Water carries solute into solution 

• This is called solvation

If the solute is covalent (non metal + non metal)

If the solute is ionic (non metal + metal)

= they dissociate into ions (the water splits apart the non metal ions and the metal ions)

= the molecules stay intact

Partial Charges Attracted to Ions

The O in H2O is attracted to the metal as the metal is positive and the H is negative

The 2 Hs in H2O is attracted to the non metal as the non metal is negative and the 2 Hs are positive

• Unsaturated solution:

• Saturated solution:

• Supersaturated solution:

• more solute can be dissolved at a given temperature and pressure

• contains the maximum quantity of solute at a given temperature and pressure

• contains more than the maximum quantity of solute than it should at a given temperature and pressure

Solubility:

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

Concentration:

amount of solute in a given amount of solution
Amount concentration = amount of solute (mol) / volume of solution (L)

c = n /v rearranged

n = c × V

V = n / c

Stock solution:

concentrated solution that is to be diluted to a lower concentration prior to use

During dilution:

Concentration decreases because volume increases and solute stays the same

Formula: 

C1V1 = C2V2

rearranged

Rearranged for C₁
C₁ = (C₂V₂) / V₁

Rearranged for V₁
V₁ = (C₂V₂) / C₁

Rearranged for C₂
C₂ = (C₁V₁) / V₂

Rearranged for V₂
V₂ = (C₁V₁) / C₂

Dilution:

the process of reducing the concentration of a substance in a mixture

 concentration(v/v) = (volume solute (mL) / volume solution (mL) ) x 100%
rearranged

* units must be the same (easiest to use mL)

Rearranged for V solute
V solute = (C × V solution) / 100

Rearranged for V solution
V solution = (V solute × 100) / C

concentration(w/v) = (volume solute (g) / volume solution (mL) ) x 100%
rearranged

* units must be g / mL

Rearranged for mass (g)
mass = (C × volume) / 100

Rearranged for volume (mL)
volume = (mass × 100) / C

concentration(w/w) = (mass solute (g) / mass solution (g) ) x 100% 
rearranged

* units must be the same (easiest to use g)

Rearranged for mass solute
mass solute = (C × mass solution) / 100

Rearranged for mass solution
mass solution = (mass solute × 100) / C

Formula: ppm = (mass of solute / mass of solution ) x 10^6 

rearranged

Rearranged for mass solute
mass solute = (ppm × mass solution) / 10⁶

Rearranged for mass solution
mass solution = (mass solute × 10⁶) / ppm

*units must be the same grams on the top and litres on the bottom

Formula: ppb = (mass of solute/ mass of solution) x 10^9 
rearranged

Rearranged for mass solute
mass solute = (ppb × mass solution) / 10⁹

Rearranged for mass solution
mass solution = (mass solute × 10⁹) / ppb

* units must be the same grams on the top and litres on the bottom

Mass conversions
mg to g:
g to mg:
kg to g:
g to kg:

• mg to g: divide by 1000
  
  

• g to mg: multiply by 1000
  
  

• kg to g: multiply by 1000
  
  

• g to kg: divide by 1000

Volume conversions
mL to L:
L to mL:

• mL to L: divide by 1000
  
  

• L to mL: multiply by 1000

Qualitative Analysis:

the identification of the specific substances present based on a unique physical or chemical property

Sequential Qualitative Analysis

Testing for ions in solution using low-solubility products (forming precipitates)

• Procedure is summarized in a flow chart

• Tests must be performed in a specific order to successfully identify the ions present

How to create your flow chart

Follow three steps in order

1. Which ions are able to precipitate with the ions we are concerned with

2. Which order were going to test the ions in 

3. Summarize it in a flow chart

to determine your starting point you have to start with the ion that will precipitate only one of two

Qualitative

Quantitative

Qualitative = qualities (descriptions)

Quantitative = quantities (numbers)

• flame test:

• precipitation reaction:

• emission spectra:

• flame test: identifies metal ions by colour (When heated, metal ions absorb energy, which pushes their electrons into higher energy levels. As these electrons fall back to their lower, original states, they release this extra energy in the form of light.)

• precipitation reaction: forms solid to identify ions

• emission spectra: light pattern from elements

Formula for pH

pH = -log[H+]

Example equation: 

How much more acidic is a substance with a pH of 2 compared to a substance with a pH of 5?

pH 2
[H⁺] = 10⁻² mol/L

pH 5
[H⁺] = 10⁻⁵ mol/L

Comparison:
10⁻² ÷ 10⁻⁵ = 10³ = 1000

Final answer:
A substance with a pH of 2 is 1000 times more acidic than a substance with a pH of 5.

• Acid:

• Base:

• Strong acid/base:

• Weak acid/base:

• Acid: produces H⁺ in water

• Base: produces OH⁻ in water

• Strong acid/base: fully ionizes in water

• Weak acid/base: partially ionizes

Oxyacids

# OF OXYGEN	NAME OF OXYANION	EXAMPLE (FORMULA)
+ 1 OXYGEN	per__ic acid	H2SO5
BASE	_____ic acid	H2SO4
- 1 OXYGEN	______ous acid	H2SO3
- 2 OXYGEN	Hypo__ous acid	H2SO2

• Neutralization reaction:

• Titration:

• Neutralization reaction: acid + base → salt + water

• Titration: lab method used to find unknown concentration using a known solution

Perc (chemical contaminant)

• Perc is a non-polar organic solvent

• It dissolves in grease (also non-polar)

• It does not mix with water → forms separate layers

• It is denser than water, so it sinks

• Oil spills vs perc spills are different:

  • oil floats

  • perc sinks → cannot be treated the same way

Flocculation & Water Treatment

• Floc = clumps of particles formed when chemicals are added

• Floc forms during flocculation

• It settles during sedimentation

• This removes suspended particles and cleans water

Water disinfection methods

• Chemical methods:

  • chlorine

  • ozone

  • chlorine dioxide

• Non-chemical method:

  • ultraviolet (UV) light

• Ammonia is added later to stabilize chlorine so it lasts longer in water

Hard water removal (softening)

Reaction:
Ca²⁺ + CO₃²⁻ → CaCO₃(s)

• Calcium ions cause hard water

• Sodium carbonate provides CO₃²⁻ ions

• Forms solid calcium carbonate (removes Ca²⁺)

Water softeners

• Used in areas with groundwater (contains Ca²⁺ and Mg²⁺)

• Resin removes hardness ions

Regeneration

• Resin becomes full of Ca²⁺/Mg²⁺ over time

• NaCl solution is used to replace hardness ions with Na⁺

• This restores the softener

Boiling water

• Kills biological contaminants:

  • bacteria

  • viruses

  • protozoa

• Does NOT remove:

  • sand

  • heavy metals

  • pesticides

  • dissolved chemicals

Why sanitation and water quality are important

• Sanitation is the safe disposal of human waste

• Poor sanitation contaminates drinking water sources

• Contaminated water spreads water-borne diseases (example: cholera)

• Clean water reduces disease and increases public health

• Improves education and productivity because people are healthier

Types of water contaminants

• 1. Physical contaminants

  • Not dissolved in water

  • Examples:

    • sand

    • twigs

    • plastic

    • suspended particles (cloudy water)
      

  2. Biological contaminants

  • Living organisms in water

  • Examples:

    • bacteria (E. coli)

    • viruses

    • protozoa

  • Cause disease and can come from sewage or animal waste

• 3. Chemical contaminants

  • Dissolved substances (solutions)

  • Examples:

    • pesticides

    • fertilizers (nitrates, phosphates)

    • heavy metals (lead, mercury, cadmium)

    • organic solvents (perc)

    • road salt

7 steps of water treatment

1. Collection

• Water enters plant

• Large debris removed with screens

2. Coagulation

• Chemicals added to neutralize particles so they stick together

3. Flocculation

• Gentle mixing forms floc (clumps of particles)

4. Sedimentation

• Floc sinks to bottom due to gravity

5. Filtration

• Water passes through sand/charcoal filters

• Removes remaining particles and impurities

6. Disinfection

• Chlorine, ozone, UV, etc. kill microorganisms

7. Distribution

• Clean water is pumped to homes and businesses

Soft water vs hard water

Soft water

• Low Ca²⁺ and Mg²⁺ ions

Hard water

• High Ca²⁺ and Mg²⁺ ions

Problems with hard water

• Does not lather well with soap

• Forms soap scum (precipitate)

• Clogs pipes and heating systems

• Creates scale in kettles and appliances

How water is softened

• Ion exchange resin replaces Ca²⁺ with Na⁺ ions

• Resin eventually becomes saturated

• Regenerated using sodium chloride solution

Key ideas from the reading

Big takeaway

• Water contamination increases when people are concentrated in one area

• Industrial and agricultural activities also pollute water

• Contaminants are classified as physical, biological, or chemical

• Safe drinking water is regulated using maximum acceptable concentrations (MAC)

• Water treatment does NOT fully purify water — it makes it potable (safe to drink)
  
  Water treatment is a multi-step system designed to:

  • remove physical particles

  • kill microorganisms

  • reduce harmful chemicals
    so water is safe for human use