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Chem Ch 5
Water for Life
| Question | Answer |
|---|---|
| Electronegativity | Measure of the attraction of an atom for an electron in a chemical bond. |
| Most electronegative element | first= fluorine; second= oxygen |
| Ideal Covalent bond and electronegativity | x and y have identical electronegativities. Most common. Neither dominate so the electrons are equally shared between them. |
| Polar Covalent and electronegativity | X and Y have dissimilar electronegativities. The one with slightly higher electronegativity will have greater control of the electrons. This end of the bond will be slightly more negative; other will be positive. |
| Ionic bond and electronegativity | X and Y have vastly different electronegativities. One with the greatest electronegativity will have full control of the electrons and have a -1 charge, and the other will surrender them and have a +1 charge. |
| Water has.... | large specific heat, large heat of fusion, large heat of vaporization, and high boiling point |
| High heat capacity | can take a lot of heat before reaction occurs |
| Solvent | Capable of dissolving 1 or more pure substance |
| Water becomes _______ when it freezes | less dense |
| Polar covalent bond | a covalent bond in which the electrons are not equally shared but rather are closer to the more electronegative atom |
| Hydrogen bond | 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. |
| Intermolecular Force | Force that occurs between two molecules (hydrogen bonding) |
| Intramolecular force | force that exists within a molecule |
| Water is ______ bonded with a ______ shape. | covalently; bent |
| Density | mass per unit volume. |
| How much water do we consume for domestic or household use? | 10% |
| How much water do we consume for industrial needs? | 20% |
| How much water do we consume for agricultural use? | 70% |
| How much water on earth is fresh water? | 3% |
| How much fresh water is easily accessible from lakes, swamps and rivers? | .3% |
| Surface water | fresh water found in lakes ,rivers, and streams. Water usually has to be treated before it is potable. |
| Ground water | less convenient to access. Fresh water found in underground reservoirs also known as aquifers. Accessed by drilling wells or using naturally occurring springs. |
| Aquifers | underground reservoirs. Water trapped 50-100 ft underground inside sand or gravel. |
| Water covers over how much of the planet? | 70% |
| Specific heat | heat required to warm 1 g of a substance by 1 degree Celsius |
| Heat of Fusion | Heat required to just melt 1 g of a substance already as its melting point |
| Heat of vaporization | heat required to boil 1 g of a substance already at its boiling point |
| Electronegativity ______ from left to right. | Increases |
| Density of ice is _______ than that of water. | Lower. Hydrogen bonds cause ice to have an open structure. As ice melts, molecules enter into these channels, the density of liquid water is higher. Allows for aquatic life, but causes burst pipes. |
| How much water do US residents use a day? | 100 gallons. Very little needs to be fit to drink. |
| What are the choices of potable water in the US? | Tap water, drinking water, filtered tap water |
| Why can't water always be used for drinking water? | Climate patterns, over-consumption, inefficient use contamination |
| Solubility | Result of an interaction between polar water molecules and the ions which make up a crystal. |
| Ionic Compounds | High melting and boiling point. Soluble in polar solvents like water. Insoluble in non polar solvents. Molten and/or aqueous solutions conduct electricity well. Formed from elements with very diff electronegativities |
| Covalent Compounds | Lower melting and boiling point. Often insoluble in polar solvents. Many soluble in non polar solvents. Molten and/or aqueous solutions poor conductors of electricity. Formed from elements w/ similar electronegativities. |
| Solvent | substance, often a liquid, that is capable of dissolving one or more pure substances. |
| Solute | Solid, liquid. or gas that dissolves in a solvent |
| Aqueous solutions | solutions in which water is the solvent |
| Non electrolyte | solute that is nonconducting in aqueous solutions |
| Electrolyte | solute that conducts electricity in aqueous solutions |
| Cation | positively charged ion. |
| Anion | Negatively charged ion |
| Ion | an atom or group of atoms that has acquired a net electric charge as a result of gaining or losing one or more electrons |
| In an ionic compound the sum of the....... | positive charges equals the sum of the negative charges |
| Surfactants | compounds that help polar and non polar compounds to mix, sometimes called "wetting agents" |
| Surfactants have a.... | polar head and a non polar tail |
| Polar head | is an anion or cation that dissolves in water |
| Non polar tails.... | dissolves in oil |
| Maximum Contaminant Level Goal | Maximum level in drinking water at which no known or anticipated adverse effect on human health would occur. (ppm or ppb) |
| Maximum Contaminant Level | The legal ppm or ppm concentration limit for a contaminant |
| Polar | having a pair of unequal opposite charges |
| Non Polar | having a pair of equal same charges |
| Electrolyte | a solute that conducts electricity in aqueous solutions |
| Valence Shell Electron Pair Repulsion (VSEPR) Theory | The valence electron pairs surrounding an atom mutually repel each other, and will therefore adopt an arrangement that minimizes this repulsion, thus determining the molecular geometry |
| Electronegativity Concept | the greater the electronegativity the more an atom attracts the electrons in a chemical bond |
| What is reverse osmosis used for? | To purify water |
| Desalination | any process that removes ions from salt water |
| How many Liters are produced a day by desalination? | 60 billion |
| Distillation | Process in which a liquid solution is heated and the vapors are condensed and collected. |
| Flocculation | is used to remove fine suspended matter. Solutions of calcium hydroxide and aluminum sulfate are added in water treatment. Creates sticky precipitate of aluminum hydroxide. |
| Spectator Ions | Ions which don't form precipitates in a precipitation reaction. Ions which are not involved in an acid base reaction |
Created by:
averyhurst1