Chemistry In The Environment Unit Test Flashcards
Percentages of Water
- Earth is 70% water
- 1% of fresh water is in liquid state
- 97% of water is in the oceans
- 2% is in icecaps and glaciers
Water Cycle
- Sun energy causes water to evaporate
- As water evaporates it cools into mist, fog and clouds
- When condensed into a liquid, it precipitates
- Then repeats
Why does water have a high boiling point and heat capacity?
- Water has strong hydrogen bonds which takes lots of energy to break
What ions are commonly responsible for hard water?
Calcium and magnesium
Methods to soften water
- Boiling
- ## Sodium Carbonate
What is aeration?
- When water is dissolved through agitated water (waterfalls, waves)
How can oxygen in water be decreased?
- Waste can lead to increased bacteria populations
- Pollutant-tolerant organisms (bacteria) can cause oxygen to decrease.
3 types of contaminants
- Physical (non-dissolvable, oil, waste, soils)
- Chemical (soluble, chemicals, pesticides)
- Biological ( Bacterial and viral, e. coli)
What are safe chlorine levels in water?
0.1 - 0.4 ppm
Above 1 ppm you can taste it
What can hard water cause (health-wise)
- Kidney Stones
- Pipe and dishwasher scaling
- Problems for industry
What is a good standard for alkalinity?
Above 80 ppm
Ph in water
- 7 is neutral, 6-9 is considered safe
- 1-6 is acidic
- 9-14 is basic
What are the 2 types of water hardness?
Temporary - can remove ions by boiling
Permanent - can’t remove ions by boiling
What can water quality kits test for
- Nitrate
- Phosphate
- Hardness
- Chlorine
- Dissolved O2
- CO2
- Silica
- Iron
Testing for ions in water
Positive test - colour change or precipitate, indicates an ion is resent
Negative test - does not mean an ion is absent
Qualities of acids
- Ph above 7
- Burns skin
- Sour taste
- Water soluble
- Turns blue litmus red
- Neutralizes bases
- Produces H2 when reacting with metals
Qualities of Bases
- Ph below 7
- Slippery on skin
- Bitter taste
- Water soluble
- Turns red litmus blue
- Neutralizes acids
Differentiate between electrolytes and non-electrolytes
Electrolytes are conductive, compounds separate into ions
Non-electrolytes don’t conduct, don’t dissociate
How can acids be strong or weak
Strength depends on how many molecules ionize in water, more ionization = stronger acid
How is each unit on the Ph scale represented
Ten fold
An increase in one is 10
Dilution
Many products and acids are diluted
Dilution causes pH values to increase
Reactions of Acids and Bases
- Combustion reactions produce oxides
- Oxides form with water to form acid rain
- Acids and bases combine in neutralization reactions to produce water and a salt compound
- Strong acids and bases produce heat (explosion)
What pH does acid rain have?
5.6 pH, slightly acidic due to dilute carbonic acid
What compounds contribute to acid rain?
Carbon dioxide, Sulphur oxide nitrogen oxides
How is carbon dioxide produced?
- Respiration
- Volcanic eruptions
- Forest fires
- Burning of fossil fuels and wood
How are nitrogen oxides produced?
- Lightning strikes
- Plant decay
- Burning of fossil fuels, 40%
- Geothermal generation, 25%
- Industrial practices, 35%
How do compounds form acid rain?
In gaseous form, these compounds can be carried long distances which gives them time to form acids with water vapour.
How can acid rain be neutralized in a lake?
Limestone bedrock
How are sulphur oxides produced?
- Combustion of coal and oil
Titrations
- The acid is called an analyte
- The base is called the titrant
How does respiration affect the atmosphere?
You breathe out gases that affect the atmosphere
What happens to a particle as speed increases?
Energy increases, then heat increases
Boyle’s law states
As the pressure of a gas increases the volume decreases, as long as the temperature and amount are constant
Charles’s law states
As the temperature of a gas increases, the volume increases, as long as pressure and amount are constant
What is one Kelvin?
273K
