1964676
Description
Flashcards by Sheridyn11, updated more than 1 year ago
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Created by Sheridyn11
almost 10 years ago
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| Question | Answer |
| Water | - the biological medium - all organisms familiar to us are made mostly of water and live in an environment dominated by water |
| What is the only common substance to exist in the natural environment in all three physical states of matter? | Water |
| How much of Earth's surface does water cover? | 3/4 of Earth's surface |
| What is the rare property of water? | water in the solid state (ice) floats when in water of the liquid state |
| Terrestrial life | land dwelling |
| cells | they are surrounded by water and consist of about 70-95% water |
| How do polar covalent bonds in water molecules result in hydrogen bonding? | oxygen is more electronegative than hydrogen, therefore, electrons spend more time closer to the oxygen than the hydrogen. this makes it polar covalent |
| polar molecule | - unequal sharing of electrons make it a polar molecule - the overall charge is unevenly distributed |
| hydrogen bond | - The properties of water arise from attractions between oppositely charged atoms of different water molecules - the slightly positive Hydrogen of one molecule is attracted to the slightly negative Oxygen of a nearby molecule - they are held together by a hydrogen bond |
| hydrogen bonding | organizes water molecules into a higher level of structural order |
| hydrogen bonds in liquid form | - very fragile - they constantly break and reform - they are 1/20 the strength of a covalent bond |
| What are the four emergent properties of water that contribute to Earth's suitability for life? | 1. cohesive behavior 2. ability to moderate temperature 3. expansion upon freezing 4. versatility as a solvent |
| cohesion | hydrogen bonds hold the substance together which contributes to the transport of water and dissolved nutrients against gravity in plants; this happens through water conducting cells |
| adhesion | - the clinging of one substance to another - adhesion of water to cell walls by hydrogen bonding helps counter the downward pull of gravity |
| surface tension | - a measure of how difficult it is to stretch or break the surface of a liquid - water has a great surface tension |
| How does water moderate temperature? | by absorbing heat from air that is warmer and releasing the stored hear to air that is cooler |
| kinetic energy | - the energy of motion - the faster a molecule moves, the greater the kinetic energy |
| Heat | - a form of energy - a measure of matter's TOTAL kinetic energy due to motion of its molecules -depends in part on the matter's volume -the more molecules in motion, the greater the heat |
| temperature | - a measure of heat intensity that represents the AVERAGE kinetic energy of the molecules - this doesn't depend on volume |
| Which contains more heat and why? A swimming pool OR A pot of coffee | The swimming pool contains more heat because it has a greater volume. |
| when two objects come together that aren't the same temperature | heat passes from warmer to cooler until it reaches equilibrium |
| How does ice cool a drink? | by absorbing heat as it melts |
| At sea level, what is the freezing point of water? boiling point? | (in degrees Celsius) Freezing point: 0 Boiling point: 100 |
| what is the average human body temperature? room temperature? | (in degrees Celsius) Body: 37 room: 20-25 |
| calorie (cal) | - a unit of heat - the amount of heat it takes to raise the temperature of 1g of water by 1 degree Celsius - also the amount of heat that 1g of water releases when it cools by 1 degree Celsius |
| Kilocalorie (kcal) | 1,000cal = 1kcal - these are the calories on food packages |
| Joule (J) | - a measure of energy (heat) 1 J = 0.239 cal 1 cal = 4.184 J |
| specific heat | the amount of heat that must be absorbed or lost for 1g of that substance to change its temperature 1 degree Celsius |
| what is the specific heat of water? | 1 cal/(g)(degree Celsius) - higher than that of ethyl alcohol (ethyl alcohol specific heat = .6 cal/(g)(degree Celsius) ) |
| heat in relation to hydrogen bonds | - When hydrogen bonds form, heat is released - When hydrogen bonds break, heat is absorbed |
| Why is the specific heat of water so high? | - because it breaks the hydrogen bonds before the molecules can move faster - this is good because it takes more heat to change the temperature of water |
| Why do the coasts have higher climates? | the water storing and releasing heat |
| What stabilizes ocean (and body) temperatures? | - the high specific heat of water - this allows for marine life |
| evaportaion | - transferring from a liquid to a gas - this occurs more rapidly with heat |
| Why do molecules of liquid stay close together? | hydrogen bonds |
| heat of vaporization | the quantity of heat a liquid must absorb for 1g of it to be converted from the liquid state to the gaseous state |
| why does water have a high heat of vaporization? | - hydrogen bonds - it evaporates at all temperatures |
| evaporation cooling | as a liquid evaporates, the surface of the liquid that remains behind cools down - this occurs because the 'hottest' molecules (the molecules with the most kinetic energy) are the most likely to leave a gas - contributes to stability of temperature in lakes and ponds and also provides a mechanism that prevents terrestrial organisms from overheating |
| Why does ice float in liquid? | - water is less dense as a solid than as a liquid because of its hydrogen bonds - lowering temperatures means that there is less movement of molecules which makes them more spread out and uniform because of hydrogen bonds |
| When is water at its GREATEST density? | at 4 degrees Celsius |
| How can life exist below a frozen surface? | with a deep body of water, the floating ice insulates the liquid water below it which prevents it from freezing |
| solution | - a liquid that is a completely homogeneous mixture of two or more substances - a solute + a solvent = a solution |
| solvent | the dissolving agent of a solution |
| Water is the 'Universal Solvent'. True or False | False. There is no universal solvent |
| solute | the substance that dissolves |
| aqueous solution | a solution in which water is the solvent |
| hydration shell | - the sphere of water molecules around each dissolved ion - this is how water molecules break down the solute |
| Does a compound need to be ionic to dissolve in water? Why? | No. Because many compounds are made up of non-ionic polar molecules, such as sugars, and they are also water-soluble |
| hydrophilic | - water-loving - any substance that has an affinity for water |
| colloid | - a stable suspension of fine particles in a liquid - examples: milk, mayo, blood, jello |
| hydrophobic | - water-fearing - substances that don't have an affinity for water - non-ionic and non-polar - hydrophobic molecules are major ingredients of cell membranes - example: oil repels water |
| why are the major ingredients of cell membranes hydrophobic? | so that the cell membranes don't break down |
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