CHEM 1100: EXAM 2
149 Cards in this Set
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Water's Interesting Properties
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Essential for life
-Unusually high boiling point and specific heat
-Can be observed in all 3 phases (Solid, Liquid, Gas)
-"Universal Solvent"
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Electronegativity
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Measure of the attraction of an atom for an electron in a chemical bond
-This yields polar covalent bonds
--Bond in which electrons are not equally shared between the two atoms
---Slight positive and negative charges
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Many of water's unique properties can be attributed to ___________________.
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hydrogen bonding and the role it plays.
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Hydrogen Bonding
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An intermolecular attraction which arises when a H molecule is bonded to a highly electronegative molecule (Usually Oxygen, Nitrogen, or Fluoride)
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Hydrogen Bonding impact on properties
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Hydrogen bonding in ice leads to a rigid hexagonal structure with holes in the middle
--Water is locked into place with 4 hydrogen bonds
---Less dense than liquid water as a result
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Hydrogen Bonding requires more energy to pull apart hydrogen bonds
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Usually high boiling point compared to other comparable molecules
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Blue Water
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Amount of surface/ ground water used in production
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Green Water
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Amount/ Volume of rain water used in production
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Grey Water
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Amount/ Volume of fresh water that is polluted during production
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Water Footprint
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An estimate (for an individual or a nation) of the amount of water required to sustain the consumption of goods and services
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Reverse Osmosis
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You push the salt water through the semi-permeable membrane and pure water comes out
-Ions are blocked by the semi-permeable membrane
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Global Climate Manage
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Climate affects supply and demand for water
-Plays important role in the timing of the water cycle and the timing of events in the ecosystem
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What is the aqueous solution 3 step process
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1. Break up solvent
2. Break up solute
3. Combine them together
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Polar solvents dissolve polar (or ionic) solutes
Non polar solvents dissolve non-polar solutes
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"Like dissolves like"
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1. Break up solvent
2. Break up solute
3. Combine them together
The bonds broken in 1 and 2 need to be roughly equal to _____.
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to bonds made in 3
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Why is water so good at dissolving things?
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When a substance dissolves, means that the solution is more stable than the solute and the solvent by themselves
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Large electronegativity difference --->
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Ionic Bond
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What is a cation
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The element that loses an electron and becomes positive
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What is an anion
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The element that gains an electron and becomes negative
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Nonelectrolyte
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Solute nonconducting in aqueous solutions
Example: Sugar
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Electrolyte
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Solute that conducts electricity in aqueous solution
Example: Salt
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Ionic Bond
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Bond formed when oppositely charged atoms attract
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Ionic Compound
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Ions in a fixed proportion and arranged in a regular structure
-the more valence electrons an atom has, the less likely it is to give them up (higher stability)
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Naming Ionic Compounds
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-Balance the charges
-Cation first
-Anion Second
--Anion ends with suffix -ide
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Periodic Table
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Row 1-2 tends to lose electron
Row 3-7 tend to gain electrons
Row 8 is a full electron shell
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Many ionic compounds are dissolved in the oceans
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Example: NaCl (s) -----H2O----> Na+ (aq) + Cl- (aq)
-Bond to oxygen in water because of the partial negative charge
Example: Na2SO4 (s)----H2O----> 2Na+(aq) + SO4^2-(aq)
-bond to the hydrogen in water because of the partial positive charge
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OH groups participate in hydrogen bonding an make molecules more polar. Polar dissolves polar and that suggests an important solubility rule:
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"Like dissolves Like"
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General Solubility Rule: "Like dissolves like"
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If both molecules are polar, they dissolve better with each other
If both molecules are non polar, they dissolve better with each other
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OH groups participate in ________. So the more -OH groups in a molecule, the more _____it is.
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Hydrogen Bonding
Polar
Example: Water
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Two familiar polar covalent compounds:
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Ethylene Glycol: main ingredient in antifreeze
-Ethanol
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Surfactants
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Surfactants help polar and non polar compounds to mix, because they have both polar and non polar groups
Example: Soap
-The non polar tail is hydrophobic, which means that it prefers to be away from water. The polar head is hydrophilic, which means that it is attracted to water.
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-The fatty acid anions (surfactants) in soaps have a long, non-polar tail, consisting of hydrocarbon chain, and a polar, anionic (negatively charged) head.
--Non-polar grease molecules are taken into the non-polar center of the clump
--Surfactants club together and stay suspended in wa…
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When surfactants are added to water, they do no spread every through the water, instead they clump together, with the negative heads pointing outwards. The negative ends interact with polar water molecules and the whole clump stays suspended in water, forming an emulsion rather than a sol…
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Safe Drinking Water Act (SDWA)
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-Regulated by Environment Protection Agency (EPA)
-The Act makes sure water is measured for the amount of harmful substances that they have and ensure people have access to clean drinking water
-Maximum contaminant level goal (MCLG) and Maximum Contaminant Level (MCL)
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What does Environment Protection Agency (EPA) look for?
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-Metals (heavy metals)
-Microorganisms
-Chlorine
-Pesticides (toxic chemicals)
-Hardness
-Fluoride
-pH
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Water Treatment
-Pure Source:
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Aquifer (underground geologic formation or porous materials)
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Disinfection Water
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A crucial step in the water treatment process
-Chlorination: accomplished by adding chlorine gas (C12)
-Some chlorine left behind to continue the disinfection process
-Some other methods of disinfecting water:Ozone, UV Light, Ultrasound
---Ozone, UV Light, Ultrasound are three methods…
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Isomers
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Same formula, but different structure
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Functional Groups
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Group of atoms that act as one molecule. Have distinctive chemical properties.
-Responsible for all drugs
--Functional Groups play a role in solubility, especially O, N, OH.
---- These higher polarity means more soluble in H2O which makes it better for drug molecules
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How does Aspirin work>
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Alters the chemical communication of the body. Hormones are chemical messenger that control said communications. Aspirin relieves pain and fever.
-Enzymes speed up chemical interactions.
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Optical Isomers
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Have the same chemical formula, but differ in 3-D orientation
-Non superimposable mirror image)
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Optical Isomer: Chiral
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There has to be 4 different groups bonded to the carbon
-One isomer may have fewer side effects and a more efficient reaction in the body
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Steroids
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A class of naturally occurring or synthetic fat solvable organic compounds that share a common carbon skeleton arranged in 4 rings.
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The phrase "like dissolve like" refers to
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Solvents dissolve solutes that have similar properties
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What are major disadvantages of using ozone instead of chlorine to disinfect water?
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Ozone is more expensive
Ozone does not protect the water from contamination after it leaves the plant
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Which compound is ionic?
CO2
MgCl2
SO2
NO2
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MgCl2
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The octet rule is applied to bonding in carbon-containing compounds. In accordance with the octet rule,
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Each carbon atom forms bonds so as to have 8 electrons around it
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What is a characteristic of a solution?
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The solute cannot be separated from the solvent by simple filtration
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Enzymes
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Biochemical catalysts that influence the rate of reactions
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What is a Ionic Compound?
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Compound composed of electrically charged ions that are present in fixed proportions and are arranged in a regular, geometric pattern
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What is a surfactant?
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A class of molecules that contain both polar and non polar regions
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Does it take more energy (per gram) to boil water or to melt ice?
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When boiling water it involves separating the water molecules complexly from all the neighbors. When melting ice on the other hand, only requires breaking off about 1 hydrogen bond per H2O molecule. Boiling water, breaks about 3- Hydrogen bonds/Water Molecules, and therefore costs more en…
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Hydrogen bonds are strong, but _____ bonds are stronger.
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Covalent
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Do different isotopes of carbon affect a drug's shape or chemical structure?
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Neutrons have no charge so they aren't attracted to (or repelled) by electrons, so the bonding and electronegative are unaffected. The chemical properties of different C- Isotopes are identical.
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How does chlorination work? How does water purification work in a well and septic tanks?
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Chlorination works so well because the formation of HOCl, and the fact that it doesn't dissociate much into ions. The neutral molecule can penetrate the hydrophobic cell walls more effectively than charged species can. Once there the Cl atom in HOCl can use chemical reactions to occur by …
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What is the difference between solute and solvent?
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Solute is a minor component of a solution
Solvent is a major component of a solution
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How does water and drugs influence the economics of climate change around the world?
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The connections for water has to do with the reliance on glacier run off for hundreds of millions of people. Climate change may stress fresh water availability. Another issue is that global warming may lead to certain diseases spreading to new regions. Malaria is one possibility which wou…
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What's the difference between ionic and covalent bonds?
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Ionic attract between ions; no electron sharing occurs between atoms having very different electronegativities
Covalent bonds share pair of electrons that occurs between atoms having similar electronegativities.
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When the ocean absorbs CO2, does it also release CO2?
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Yes, the oceans are constantly exchanging lots of CO2 with the atmosphere. One of the other potential feedback loops occurs because CO2 is less soluble in warmer water (soda goes flat when warm) meaning more CO2 will be released in warmer ocean water.
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How do drugs mimic neurotransmitters?
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Shape and polarity.
Drugs like cocaine, nicotine and methanphetamine act to disrupt the normal neurotransmitters. Because there are several classes of neurotransmitters affecting different physiological functions different drugs affect difficult neurotransmitters.
Cocaine blocks the st…
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Trihalomethane
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The compounds classified as THM are byproducts of water chlorination. They are controlled by EPA because they are potentially carcinogenic.
Examples: CHFCl2, CHCl3, CHClBr2, CHCl2Br. CHICl2, etc.
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When is International World Water Day?
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March 22nd
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Water is the only common substance that can exist as a ______,________,_______ at average Earth Temperatures.
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Solid, Liquid, Gas
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Because ice floats on water, ecosystems in lakes and streams can survive beneath the ice during frigid winter days. Water also absorbs more heat per gram than most other substances, allowing bodies of water on Earth to serve as heat reservoirs.
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True.
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When water freezes
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it expands
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What is electronegativity?
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A measure of the attraction of an atom for an electron in a chemical bond.
The scale runs from 4.0-7.0
*The greater the electronegativity, the more an atom attracts the electrons in a chemical bond toward itself.
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For covalent substances, as the molar masses increases,
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the boiling point increases
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What elements have the highest values?
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Florine(4.0) and oxygen (3.5)
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Electronegativity on the periodic table
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Values increase from left to right in a row of the periodic table (from metals to nonmetals) and decrease going down a group.
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The greater different in electronegativity between two bonded atoms, the more
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polar the bond is.
**** if the electronegativity difference between two atoms is more than 1.0, the bond is considered polar covalent. If it is greater than 2.0, the bond is considered ionic.
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What is a polar covalent bond?
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a covalent bond in which the electrons are not equally shared but rather are closer to the more electronegative atom.
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What is a non polar covalent bond?
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a covalent bond in which the electrons are shared equally or nearly equally between atoms.
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Intermolecular Forces vs. Intramolecular Forces
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Intermolecular Forces are between molecules whereas intramolecular forces are within molecules
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What is Hydrogen Bonding?
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is an electrostatic attraction between a H atom bonded to a highly electronegative atom (O, N, or F) and a neighboring O, N, or F atom, either in another molecule or in a different part of the same molecule.
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Is water in a solid state or liquid state have a greater density?
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Density, the mass per unit volume, of liquid water is greater than that of ice.
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What do hydrogen bonds do?
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The hydrogen bonds help stabilize the shape of large biological molecules, such as proteins and nucleic acids.
Example: The double helix structure of DNA molecule is stabilized by the hydrogen bonds between the two DNA strands.
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What is specific heat?
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the quantity of heat energy that must be absorbed to increase the temperature of 1 gram of a substance by 1º C.
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Because of water's high specific heat, large bodies of water influence regional climate. When the water evaporates the heat is _____.
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Absorbed.
-By absorbing large quantities of heat, the oceans and water in the clouds help moderate global temperatures.
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What is potable water?
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Water safe for drinking and cooking.
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What does non potable water contain?
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Contaminants that include particulates from dirt, toxic metals such as arsenic, or bacteria that cause cholera.
-Although not drinkable, it still has a use to wash sidewalks, to reduce roadway dust, or to irrigate!
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Where is fresh water found on our planet?
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The most convenient source for human access is surface water, the fresh water found in lakes, rivers and streams.
The less convenient to access is ground water, freshwater found in underground reservoirs also known as aquifers.
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How much of the water on our planet is fresh water?
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Only about 3%; the remainder is salt water.
2/3 of this fresh water is locked up in glaciers, ice caps, and snowfields.
Lakes, rivers, and wetlands account for a mere 0.3% of the fresh water.
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How is it possible to drink seawater?
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Seawater is drinkable only if we remove its salt through a process called desalination.
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What can water easily dissolve?
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Salt, Sugar, Ethanol, SO2 (air pollutant)
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What is hard for water to dissolve?
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Limestone rock, CO2, Oxygen
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Polar Covalent Bond
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A covalent bond in which the electrons are not equally shared but rather are closer to the more electronegative atom
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Intramolecular force
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A force that exists within a molecule
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Intermolecular force
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A force that occurs between molecules
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Density
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The mass per unit volume
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Water footprint
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An estimate (for an individual) of the amount of water required to sustain the consumption of goods and services.
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Surface waters
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The fresh water found in lakes, rivers, and streams
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Concentration
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The ration of the amount of solute to the amount of solution
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Desalination
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Any process that removes ions from salt water
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Freebase
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a nitrogen containing molecule in which the nitrogen is in possession of its lone pair of electrons
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The phrase "like dissolve like" refers to
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solvents dissolve solutes that have similar properties
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What are the major disadvantages of using ozone instead of chlorine to disinfect water?
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Ozone is more expensive
Ozone does not protect the water from contamination after it leaves the plant
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The octet rule is applied to bonding in carbon-congaing compounds. In accordance with the octet rule,
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each carbon atom forms bonds so as to have 8 electrons around it
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What is a characteristic of a solution?
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The solute cannot be separated from the solvent by simple filtration
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What is an enzyme
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Biochemical catalysts that influence the rate of reactions
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What is an ionic compound?
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Compound composed of electrically charged ions that are present in fixed proportions and are arranged in a regular, geometric pattern.
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What are surfactants?
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A class of molecules that contain both polar and non-polar regions
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What are properties of water?
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High boiling point
Universal solvent
Can be seen in all 3 phases
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Electronegativity
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Atoms that are attract electrons very strongly
yields polar covalent bonds
electrons are not equally shared
slight positive and negative charges
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Hydrogen Bonding
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What a Hydrogen molecule is bonded to a highly electronegative molecule, usually O, N, or F
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Reverse Osmosis
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Push salt water through semi permeate membrane and pure water comes out
Ions are blocked by the membrane
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Why is water so good at dissolving things?
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Aqueous solutions are more stable than either the pure solvent or put solute alone
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The more OH groups in a molecule the more
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polar they are
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chlorination
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disinfecting water, some Cl left behind to continue disinfecting process
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Functional Group
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Group of atoms that act as one molecule; have distinctive chemical properties
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__% of all water is in oceans
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97%
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__% of is fresh water
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3%
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_-% of freshwater is in glacier and ice caps
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69%
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What is virtual water?
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Amount of water that is used to make a product.
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What is the importance of water have high melting and boiling points?
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We can observe all 3 phases: liquid, solid, and gas
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What is the importance of H2O having a "high" heat of vaporization
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Condensation
Releases engery
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Do atomic compositions and molecular geometry affect the physical proponents and solubility
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Yes
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Polar Covalent Bonds
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A shared pair of electrons where the pairs is not shared equally
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Electronegativity
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The relative ability of an atom in a bond to attract electrons to itself
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Electronegativity goes up as you go___ and to ____ on the periodic table.
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up
right
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The 4 most electronegative atoms and their charges are
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F (4.)
O (3.5)
N (3.)
Cl (3)
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Hydrogen Bonding
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Hydrogen bonded directly to O,N, f in the intermolecular bonds
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H2O molecules in ice arrange themselves to max the number of ___
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hydrogen bonds
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Ice has a ____ density
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Low
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Density of ice is ____ than density of water.
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Less
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Chemical compositions and structures of the solutes and their interactions with H2O determine
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Solubility
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What is the Universal Solvent?
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Water
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What is a solvent?
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The substance doing the dissolving (There is more of this in the substance)
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What is a solute?
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The substance(s) that are being dissolved (There is less of this substance)
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What is a solution?
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Homogenous mixture of solvent and one or more solutes
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When the electronegativity difference get very large, there is no more hearing of electrons
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True
Ionic Bond
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Electron transfers from the ___ electronegativity atom to the __ electronegativity atom.
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least
most
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Ionic bonds no not create molecules but
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an ionic lattice
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What is molarity?
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How much solute there is in ppm by mass
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Unit of molarity
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Moles solute/ L solution
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Why is water so good at dissolving things?
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Because when a solute dissolves that means the solution is more stable, or has a lower energy, than the solute and solvent separately
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Process of dissolving
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1. Break of solvent.
2. Break of solute
3. Combine them together
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1. Break of solvent.
2. Break of solute
3. Combine them together
If the energy used for step 1 and 2 are about equal to the energy given back in step 3 then the substance
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dissolves
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1. Break of solvent.
2. Break of solute
3. Combine them together
If the energy used for step 1 and 2 are much less than the energy given back in step 3 the substance is
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insoluble
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Oil doesn't mix with water because
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its a hydrocarbon which is nonpolar
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There are no strong attractions between oil and water because
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there are no slightly + or slightly - ends
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Like dissolve ____
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like
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Soap
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Surfactant
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What two acts do the EPA regulate?
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Clean Water Act
Safe Drinking Water Act
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What does the Safe Drinking Water Act (1974) regulate/ set?
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Maximum contaminate goals
Maximum contaminate levels
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What are three steps of water purification?
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1. Find a pure source
2. Treatment Plant
3. Disinfect and protect
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What is the main pure source used to obtain water?
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Aquifer
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What is an aquifer?
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Underground geological formation of porous material
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What are the steps for water purification at the water treatment plant?
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Coarse filtration
gel
aeration
chlorination
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What is a surfactant?
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Have both polar and non polar regions
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What are some chemicals used to disinfect and protect water?
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Chlorine
NaOCl
Ca(OCl)2
Solution Chloramine
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CHEM 110O: EXAM 3