Water quality and composition

Water Quality Overview

• Focuses on the presence of foregin substance in water and their effects on environment and health.
• Standards are needed to assess water suitability for specific uses.
• Water quality is affected by human activities and direct discharge of municipal or industrial wastewater.

Water Composition

• Water has a high tendency to dissolve other substances.
• It Is rarely found in nature in its pure condition.
• Even mountain streams contain some natural impurities in solution and in suspension.
• Rainfall picks up dust particles, oxygen, and carbon dioxide affecting water quality.
• Surface runoff collects silt, bacteria, organic material, and dissolved minerals changing water quality.
• Groundwater contains more dissolved minerals because of prolonged contact with soil and rock.

Chemistry Fundamentals

• Chemistry is the study of the composition and properties of substances.
• It also explores how elements react and combine to form compounds.
• Compounds which re substances made of combinations of basic elements.
• A molecule is the smallest part of a chemical compound with the same chemical properties as the compound.

Matter states/phases

• Matter can exist in four states i.e. solids, liquids gases and plasma.
• Solid state atoms/molecules are ordered with a relatively stable geometric form and a defined shape and volume.
• Liquid atoms/molecules are less ordered and have a variable shape, definite volume and they can flow.
• Gases atoms/molecules are completely disordered and have neither a fixed shape nor volume.
• Plasma exists as gas-like clouds and contains a large portion of charged particles like ions or electrons.
• Plasma is the most abundant form of ordinary matter in the universe and can be found in stars, including our Sun.

Chemical Formulas

• Chemical formulas show molecules made up of atoms using their corresponding symbols.
• Water's chemical formula is H₂O which means "H-two-O.”
• The subscript 2 shows there are two hydrogen atoms in a molecules of water.
• Iron oxide's (rust) formula is written as Fe3O4, this means three atoms of iron and four atoms of oxygen are in one molecule of the compound.

Organic vs Inorganic Compounds

• Organic compounds are complex and carbon-based, combined with elements like hydrogen and oxygen.
• Proteins, carbohydrates, and lipids are examples of organic compounds.
• They Are mostly related to living things
• Inorganic compounds usually lack carbon except for carbon monoxide and carbon dioxide.
• Inorganic compounds can be found more in the inanimate world.
• They feature in water or wastewater treatment operations.

Atomic Structure Basis

• The way in which elements combine to create compounds is based on the atomic structure.
• Simplified model of atomic structure includes a dense center called the nucleus comprised of.
  • Protons: positively charged particles
  • Neutrons: Particles with no charge.
  • Electrons: These are very light, negatively charged particles that spin around the atomic nucleus in certain shells or orbitals.
• Atoms that have an equal amount of electrons and protons are said to be neutral.

Atomic Number

• The atomic number represents the number of protons found in the nucleus of an atom.
• Every element has another atomic number.
• Hydrogen's atomic number is 1.
• Oxygen's atomic number is 8.

Atomic Weight

• Atomic weight, or the total number of protons and neutrons in the nucleus.
• The atomic weight of hydrogen is 1.
• The atomic weight of oxygen is 16.

Electrons Orbitals

• An element's chemical behavior is mainly depended of the amount of electrons in the atoms outermost shell.
• The orbital closest to the nucleus can contain at most two electrons for stability.
• Stability for the second orbital is achieved with eight electrons.
• Larger atoms come equipped with other orbitals for electrons.

Molecule Formation

• Compounds are formed by atoms transferring or sharing their electrons.
• During ionic bonding, electron transfer occurs, where, in covalent bonding, electrons are shared to stabilize orbitals.
• Sodium chloride (NaCl) development is formed by an electron transfer from the Na outer shell to Cl outer shell.
• Sodium's (Na) atomic number is 11
• Chlorine's (Cl) atomic number is 17

Ionic vs Covalent bonds

• Sodium (Na) has only one outer orbit electron.
• Chlorine (Cl) has seven outer orbit electrons in the figure right.
• Atoms need eight electrons in their outer most orbit for stability.
• Therefore atoms with unstable outer orbits are known as "chemically active".

Ionic Bonding Formation

• Sodium loses outermost electron, and because more electrons are available it obtains a positive charge.
• Chlorine receives an electron and becomes negatively charged
• Due to ionic bonds, the opposite charges attract allowing sodium to become NaCl.

Water Molecules

• During H2O formation, the two hydrogen atoms tend to share their electrons with the oxygen atom.
• No neutrons or electrons are gained or lost. The water molecule has a total of 10 protons and 10 electrons.
• Hydrogen contains one proton on the nucleus, and oxygen has 8 protons and 8 neutrons.
• Since the water has the same number of proton and electron then it means it has a neutral charge.
• Oxygen atom and the hydrogen atoms share electrons via covalent bonds, however the sharing is not equal.

Solutions

• A solution is a uniform mixture consisting of 2 or more substances in only phase either solid, liquid or gas.
• Aqueous solutions represent solutions of water.
• Carbon monoxide (CO) dissolving in air is a gaseous solution.
• Carbon, C, and manganese Mn, dissolving in iron to create steel, makes a firm solution.
• In mixtures like this, the solvent is the substance present in the largest amount while the solute are the ones present in smaller amounts.
• The properties of solutions are different from the properties of the solvent.
• For example, adding salt NaCl, to lower its freezing point below zero.

Solutions Properties

• Solid ones become more soluble in warm water as compared to cold water.
• The solubility of gases relies on temperature.
• The solubility of a gas decreases as temperature increase.
• Measuring concentration of gases such as chlorine, oxygen and carbon dioxide is important in environmental technology.
• "Mg/L" means milligrams/liter of the concentration of oxygen in the water.

Aqueous Solution Properties

• In an aqueous sugar solution, the sugar molecule identity continues unchanged
• They don't break into molecule pieces either.
• The unchanged or unchanged sugar molecules are scattered across the water molecules.
• After a time if more sugar is contained, the sugar molecules stops dissolving. So it becomes a saturated solution.

Ionization

• Dissociated substances will break apart when they dissolve, and form electrically charge particles known as ions. This process is ionization.
• Sodium chloride (NaCI) dissociates in water:
• NaCl -> Na+ + Cl-
• Sodium chloride dissolves -> positive sodium ions and negative chloride ions are produced.

Suspensions and Colloids

• Suspended substances mix with fragments larger than molecules.
• Suspended substances properties vary from those of real solutions are important in environmental technology
• A real solution means solute partials do not come out for any amount of time.
• True solutions cannot be physically separated from their solvent by conventional filters.
• However suspended particles will settle from waters due to gravity.
• Therefore filters can get rid of suspended particles.

Suspensions types

• Large relative particle suspensions are called coarse suspension.
• Large particles will generally exit from still water after minutes.
• Finer particles require hour to settle out.

Colloids

• Extremely Fine ones (< to 0.1 μm).
• Their too small to settle out via gravity or most filters.
• Smaller than coarse suspensions but larger than particles in true solution.
• colloidal particles repel themselves to keep distance.
• Making in near impossible to form larger and heavier ones.

Where can colloids be found

• Colloids are available in both both water and air.
• They appear in water with clay particles.
• They appear in air with smoke.
• Like what's in the a true solution, the particles in a colloidal suspension are undetectable by an microscope. -Colloidal particles scatter light unlike the way light behaves with true solutions meaning it will show the Tyndall effect.

Concentrations

• Solutions, suspensions, and colloids characteristic are strongly governed by the concentration levels.
• concentrations need quantitative expression.
• concentrations are usually expressed in terms of:
  • mass per unit volume
  • parts per million or billion
  • percent.

Mass per Unit Volume

– mg/L is the concentration of something most used

• If a 10 mg of oxygen is dissolved in liter of water then the concentration is 1 mg/L
• Solve: 0.3 g is solved in 1500 mL of water.
  • 0.3 g equals 300 mg.
  • 1 g equals 1000 mg; 1 L equals 1000 mL so 1500 mL equals 1.5 L therefore the concentration is 300 mg, 1.5 L which equals 200mg/L

Mass per Unit Volume

• Very diluted solutions can be written as micrograms per liter (µg/L) is convenient.
• 1000 µg is = 1 mg,
• Use a µg/L value conversions to mg/L, and move the decimal point three left. Then with µg/L going of to mg/L then more three right.
• Solve: 0.004 mg/L concentration is what of µg/L?
  • This is the same as : 4 μg/L.
• Solve: What's 1250 µg/L concentration written as mg/L?
  • 1.25 mg/L.
• In the air, the amount for grams or particular matter are represented as cubic meter (µg/m³).

Parts per Million (PPM)

• Liter of water has 1 mg of mass and a kilograms. This kilogram represents 1000 g, or about a million milligrams.
• "Parts per million" means that there is 1 mg of a substance for every million mg of water in that solution giving a concentration of
• If a solution as 1mg for water as 1mg of total water it can be expressed as 1 ppm
• The expression of "one pot per million parts" Is 1 inch over 16 miles, or 1 second over 12 days
• To simplify a 1 L of the concentration as 1mg for milligrams and PPM. That's 1 mg/L = 1 ppm

Very Dilute Concentrations

• Very dilute amounts are often expressed parts per billion (ppb), compared to parts per million and 1 ppb = 1 μg/L3.
• A concentration of 0.005 ppm can be written as 5 ppb.
• One part per billion means 33 year long second and a one penny over 10 million dollars.
• Very tiny concentration can affect human health and environmental quality.

Sensitive Analytical

– New tech instruments measure what is nanograms per liters.

• The amount is called" trace amounts" for substance that for liter
• 1 ng/L = 1 ppt since they are equivalent
• In professional practice best express chemical substance with mass with volume so: - use mg/L more than ppm and - use ug/L more then equivalents of ppb.
• To that extend "ng/L" should be chosen not "ppt" for expressiveness.
• But to understand one another between students in enviro, environmental student who understand each term is most recommended.

Percentages Concentrations

• Percent amount often in terms of 10,000 mg/L, so.
• Convert 1 percent equals 10,000 mg/L for practical purposes.
• Even though solutions has more dense pure water. Follows these simple equation:
• 1l = 1 kg = 1000g
  • 1g = 1000mg -So for 1L to have equals to 1,000,000 mg

Conversions with math

10,000mg/L = 10,000mg/1,000,000 mg - To simply simply use the conversion factor divide by 100 and mg equals the first mg.

• 1 mg /100mg = 1 percent.

1. If the question asks the concertation of ocean water salt when it's 45,000mg/L, then to percents then uses percent solid in waste water to mg/L by reverse and dividing.

• 1 L = 1 kg = 1000 g, 1g = 1000 mg and 1L= 1,000,000
  • Convert to per cent salt by dividing over 10,000 which we can determine the factor .0001. So 4.5 percent. To convert to mg/L multiply by 10,000 which can get us to 40,000mg/L solids.

Equation

• So it can show amount of solute that goes as compute mass Percent : mass of solute mg/ over the amount of volume over to one hundred. Mass = % = (mass solute/mass solvent 100 )
• Solving. 500-ml amount of aqueous solution is dissolved with 125 over mass of salt dissolved. what's mg, ppm, percent?
• (a) mg/L, 125 /500 L x (multiply) 1000mL = 250 mg/L
• (b) ppm, 250mg/L = 250 ppm
• (c) percent, is to find amount salt dissolved to one-hundred 500 mL water there for what's salt Solve of salt dissolved: 125 mg/L over mass of salt
  • 500 Water mass equals mass of 500 gives percent = 0.125g/ over amount grams a-times over 100- equals to 0.025 %

Acids, Bases, and pH

• An acid is a substance that causes an increase in the hydrogen ion (H+) concentration.
• An example: Hydrochloric acid, HCl, is example of a strong acid dissociating in water to form a H+ and Cl- ions.
  • This greatly increases the H+ concentration in the water. – A base is a substance that creates increases of (HO -) concentration.
• Sodium hydroxide (NaOH: the increase with the Na+ and O+ (increases increases OH)
• Similar for NaOH alkaline base (a substance that that increase to concentration) means increase substances can be increase to concentration

Acids, Bases, and pH continued

• Acids- can be characterize in strong or weak depending how intense relative concentrations of H+ OH
• Chemical reaction where acid + base together is can be is neutralization.
  • 2 product of neutralization reaction with water added equals to salt.
• With example with Sodium and HCL equals the chemical equation for neutralization -HCL + NaoH gives Nacl+ h20

pH Scales Details

• It is dimensionless number this represents is either acidic or basic
• scale ranges from 0-14.
• Mid-range = 7 this shows neutral pH or that is not nor base
• Water is neutral since it contains the same amount of hydrogen ions hydroxyl.
• If less the number has below the 7 then acidic but bigger than it’s alkaline

pH Scale Details Further

• pH also can be use to indicate strength intensity of solutions
• pH value is 7 then it will neither be acidic nor basic
• pH is logarithmic scale base 10 where it measures each change represents x10 change the acidity degree the scale for a solution for example:
  • If it pH number equals 5 this this can represent a x10 more then a solution with 6 pH because it will mean than other it’s 6 the pH scale is use scale.

Organic Substances

• Is main characteristics is carbon in combination between these elements (H, O). With many structures (chains , ring, chains), carbon is a the of atoms.
• Atoms connect. For examples a few complex structures exists of carbon (molecules that aren't fully understood- by sciences .
• The structures is rings- is what's hexagonally by this process. and made of the bonds. all and
• Can can it's with for the both both exists is an with't and and

Organic Substances

• Hydrocarbons mean carbon hydrogen.
• This simplest simple carbon with a hydrogen is is the CH4
• It occurs where naturally carbon is sludge or garbage which can be used instead because there are decaying from those.
• Butane is this carbon simple can this in that occurs where hydrogen bonds is a for garbage.
• A carbon hexagonally benzene (hydrogen 6) is is structure is carbon.

Atoms Bonding

• Alcohols means are means are carbon in atoms
• Can that or by the
• With carbon by there are hydrogen's can classify these in classification atom which replaces by hydrogen. or alcohol.
• By chemical means is where group by carbons this classification a has to be of a. Where fuel which and the in is in is methanol.

Methane and Hydroxyl

• Methanal H atom formula: H- 2-O , H with carbon connecting 3.
• Because the is connects the to with to with in
• Methane this to will replacing what where methane this molecule's the can there carbon hydroxyl.
• Because the the is is