Water Quality Management - Lec 1 Part 2

Water properties

What does it mean when we say water is a polar molecule?

It has oppositely charged ends because oxygen still has some unpaired electrons, making it negative and hydrogens positive

Water molecules form ____ bonds between the positive and negative ends of two molecules.

Hydrogen

What is cohesion and what is it responsible for?

Attraction to other water molecules, surface tension

What is surface tension and which water property is responsible for it?

A measure of the force necessary to stretch or break the surface of a liquid

What is adhesion?

Attraction of water to other substances that it can form a hydrogen bond with - doesn’t have to be polar

What is capillary action and what property(s) is/are responsible for it?

Capillary action is the ability of water to flow upwards without a pump. Cohesion and adhesion.

The capillary action effect gets ____ (less/more) with a wider tube because…?

less, water can only hold so much weight before surface tension is overcome

What is specific heat?

The amount of heat that must be absorbed or expended to change the temperature of 1 gram of a substance by one degree celsius

What is water’s specific heat like and what does this mean in layman’s terms?

Water’s specific heat is high, meaning water does not heat up or cool down very quickly.

What is latent heat/heat of vaporization and what happens to the hydrogen bonds when this occurs?

The amount of energy required to turn 1 kg of liquid water into a gas. Hydrogen bonds are broken

Water is know as a _____ due to its ability to form hydrogen bonds, making it very versatile.

Universal solvent

Solid water/ice is _____ (more/less) dense than liquid water. This property is responsible for..?

Less, ice floating

Water is most dense at what temperature?

4 degrees Celsius

Is air or water bigger? Something that is _____(airtight/watertight) is almost always _____(airtight/watertight), but something that is _____(airtight/watertight) can still leak ____(air/water)

Air is bigger. Airtight, watertight, watertight, air

Is dry air or moist air denser/heavier? What phenomenon occurs because of this?

Dry air, clouds

What does pH determine?

Solubility of nutrients and metals, availability of these chemicals for use by aquatic life

What is the main factor contributing to the pH of water?

Geology/soils

Rain has a pH ____ (lower/higher) than 7 due to…?

Lower, it has dissolved acids (CO2, sulfur oxide, nitrous oxide)

True or false? pH can be negative

True. A pH of -0.1 results in a hydrogen concentration of 1.3M/L.

In eastern Canada, pH is ____ compared to western.

Lower

What phenomenon dissolves metals and makes them water soluble?

Acid rain

What does water soluble mean?

The item that is water soluble dissolves and mixes evenly with the water, rather than settling to the bottom.

How do the following factors affect pH? Explain.

1. Algal blooms

2. Bacterial activity

3. Water turbulence

4. Chemicals flowing into water body

5. Sewage overflows

1. Increases - CO2 is removed and hydroxide is increased

2. Decreases - Organic material is decomposed and CO2 is released, reacting w/ water to form carbonic acid (H2CO3)

3. ????? Check this question lowkey

For most fish, the _____ the pH, the better, because a ____ pH causes the release of _____

Higher, low, metals

What is alkalinity and what are the three types? Where does alkalinity come from?

The ability of water to neutralize acid (having a pH greater than 7.0), acts as a buffer, bicarbonate, carbonate, hydroxide, rocks

What is conductivity? What is it an indirect measure of?

How good the water is at conducting electricity, salinity.

What is specific conductance an indicator of? What reduces it?

Hardness of water, rain

What is salinity a measure of? What are the words used to describe salinity levels? How is salinity measured?

Percentage of salt. Fresh water, brackish, moderately saline, saline, sea water. Boiling water.

How is turbidity measured?

Light is passed through a sample, and a photocell (device used to measure light) is set at a 90 degree angle to measure scattered light

What is the main factor determining what properties your water has?

The geology of the soil/rocks

Water clings to ____ molecules, causing them to be soluble in water.

Polar

What is thermal expansion?

The tendency of matter to increase in size with increasing temperature

What are the three ways oxygen gets into water?

1. Diffusion from surrounding air

2. Aeration

3. Photosynthesis

Explain how dead zones are created

1. Excessive nutrients enter water body, for example from agriculture (or wastewater)

2. Nutrients cause algae to form and reproduce very quickly 9algal bloom)

3. Water doesn’t have enough nutrients/light/space for all the algae being made, and so it dies and falls to bottom of water body

4. Algae is decomposed by bacteria, which consumes oxygen

5. Dead zone is formed as critters need oxygen

If all ions are correctly determined by a lab, then the…? What percentage of difference is considered acceptable before you should start questioning lab results?

Sum of cations should equal sum of anions. 5%

What is the formula for equivalent concentration?

Equivalent concentration (Meq/L) = concentration mg/L / (formula weight g/mol / charge)

What is the formula for chlorophyll concentration in summer?

CHL (mg/m³) = 0.0731(TP mg/m³)^1.449

What is the formula for loss rate of total coliform bacteria in water bodies?

kb’ = kb1 + kbi + kbs
where kb’ is loss rate for total coliform bacteria in water bodies
kb1 is base mortality rate
kbi is loss rate due to solar radiation
kbs is loss rate due to settling
all units are day^-1

When is max concentration?

When x = vt