Term
| What does the polarity of water molecules result in? |
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Definition
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Term
| What are the bonds called that hold atoms in water molecules? |
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Definition
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Term
| What type of charge does the oxygen region have? The hydrogen region? |
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Definition
Oxygen-negative
Hydrogen-Positive |
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Term
| What types of bonds are two water molecules held together by? |
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Definition
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Term
| How many bonds can one water molecule form? |
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Definition
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Term
| Cohesion is the attraction of... |
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Definition
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Term
| Is hydrogen bonding strong or weak? |
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Definition
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Term
| How long do hydrogen bonds last? |
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Definition
| A few trillionths of a second |
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Term
| How often do water molecules form bonds with new partners? |
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Definition
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Term
| What are two examples of cohesion? |
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Definition
1. Transport of water in plants against gravity
2. Transpiration through leaves- tugs water up veings of stalk then to the leaves- great tensile strength |
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Term
| How long did life spend evolving in water? |
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Definition
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Term
| What percentage of cells are made up of water? |
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Definition
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Term
| Which is more electronegative, oxygen or hyrogen? |
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Definition
| Oxygen- which is why the electron spends more time closer to the oxygen atom |
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Term
| What is the shape of a water molecule? |
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Definition
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Term
| What type of molecule is the water molecule and what does that mean? |
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Definition
| It is a polar molecule- the opposite ends of the molecule have opposite charges |
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Term
| What type of attractions exist between water molecules? |
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Definition
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Term
| When water is in its liquid form, how strong are its hydrogen bonds? |
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Definition
| 1/20th as strong as convalent bonds |
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Term
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Definition
| The attraction of unlike molecules |
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Term
| Give two examples of adhesion |
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Definition
1. Water attraction to soil particles
2. water attraction to the sides of xylem wallas (counteracts the pull of gravity and prevents the walls from breaking) |
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Term
| Is it the tendency of a liquid to maximize or minimize surface tension? |
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Definition
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Term
| Surface tension is the result of what force? |
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Definition
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Term
| Surface tension is the result of water molecules being more attracted to _______ vs. _______ |
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Definition
| each other than to air molecules |
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Term
| Surface tension acts like an ___________ ________. |
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Definition
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Term
| Surface tension confines moelcules in an area that has the least what? |
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Definition
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Term
| What shape do molecules resist because of surface tension? |
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Definition
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Term
| Water striding above the rim glass is an example of what? |
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Definition
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Term
| What allows bugs to walk on water? |
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Definition
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Term
| If water striders weighed more or had pointed legs what would happen to its ability to walk on water? |
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Definition
| It would be unable tod o so because it would rupture the surface film (caused by surface tension) |
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Term
| Compared to other liquids, does water have a greater or lesser surface tension? |
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Definition
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Term
| What allows people to skip rocks on a pond? |
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Definition
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Term
| How does water moderate the temperature on earth? |
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Definition
| It absorbs heat from hot air, and releases stored heat into cooler air. |
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Term
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Definition
| The measure of the total kinetic energy due to the molecular motion of a body of matter. |
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Term
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Definition
| The measure of the intensity of heat due to the average kinetic energy of molecules |
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Term
| What is heat measured in? Temperature? |
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Definition
| Heat- Calories Temperature-celsius |
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Term
| Explain how heat and temperature are related using a swimmer and a pooling a the example. |
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Definition
| Swimmer has a higher temperature, but the pool has more heat due to its great volume |
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Term
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Definition
| The amount of heat it takes to raise 1g of water 1c and vice versa. |
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Term
| Why is water effective as a heat bank? |
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Definition
| It can absorb or release a large amount of heat with only a slight change in its own temperature. |
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Term
| When two objects are brough together, how does heat pass from one object to the other? |
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Definition
| Heat passes from the warmer object to the cooler object until they are the same temp. |
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Term
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Definition
| The amount of heat that must be absorbed or released in order for 1g of a substance to change its temp by 1c |
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Term
| How does water's specific heat compared to alochol's specific heat? |
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Definition
Water= 1 calorie
Alcohol= .6 calories |
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Term
| When heat is absorbed what does it do to hydrogen bonds? |
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Definition
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|
Term
| When heat is released what does it do to hydrogen bonds? |
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Definition
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Term
| What are two reasons why it is important that water has a high specific heat? |
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Definition
1. Creates a stable ocean temperature that is favorable for marine life
2. Allows life to resist changes in their temperatures b/c bodies have a high composition of water |
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Term
| Why can you burn your fingers on an iron pot handle, when the water in the pot is still luke warm? |
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Definition
| Iron has a specific heat that is 10 times less than water. It only takes .1 Calorie to raise the temp. of iron. |
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Term
| Why does a calorie of heat cause a relatively small change in the temperature of water? |
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Definition
| Much of the heat energy is used to disrupt the hydrogen bonds, before the water molecules can begin moving faster. |
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Term
| Why do coastal areas generally have a milder climate than inland regions? |
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Definition
| High specific heat- it can absrob and store a huge amount of heat in the day time while only raising its temp a few degrees. The gradually cooling water can then warm the air. |
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Term
| What happens to molecules that are moving fast enough to overcome their attraction to other molecules? |
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Definition
| They can enter the air as a gas. |
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Term
| What is heat of vaporization? |
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Definition
| the quantity of heat a liquid must absorb for 1g to be converted into a gas |
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Term
| Does water have a high or low heat of vaporization and why? |
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Definition
| High- Hydrogen bonds must be broken before molecules can leave the liquid |
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Term
| What is waters heat of vaporization and how does this compare with alcohol? |
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Definition
| 580 Calories of heat- nearly double the heat of vaporization of alcohol |
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Term
| How does heat of vaporization moderate earth's climate? (4 steps) |
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Definition
1.Solar heat is absorbed by the seas 2.evaporation
3.moist tropical air circulates poleward
4.releases heat as it condensese to form rain. |
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Term
| What happens to the surface of a liquid as the liquid evaporates? |
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Definition
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Term
| What does evaporative cooling have to do with lakes and ponds? |
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Definition
| It contributes to their stability |
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Term
| What does evaporative cooling prevent in organisms? |
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Definition
| It prevents them from overheating (sweat- animals, water from leaves of plants) |
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Term
| Why does evaporative cooling occur? |
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Definition
| The hottest molecules, those with the greatest kinetic energy, are the most likely to leave as a gas. |
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Term
| Why does high humidity increse discomfort? |
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Definition
| The high concentration of water vapor in the air inhibs evaporation of sweat from the body. |
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Term
| Is water less dense as a solid or liquid? Why? |
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Definition
| Solid because water expands as it solidifies due to hydrogen bonding. |
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Term
| At temperatures above 4C how does water behave? |
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Definition
| Like other liquids- expanding as it warms and contracting as it cools |
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Term
| When does water begin to freeze? |
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Definition
| OC- when its molecules are no longer moving fast enough to break the hydrogen bonds |
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Term
| When water freezes what does it become locked into? How many partners are each molecule bonded to? |
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Definition
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Term
| How much lense dence is ice compared to liquid water at 4C? Why? |
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Definition
| 10% less desne because the hydrogen bonds are far enough apart |
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Term
| What happens as ice begin to absorb heat, causing the temperature to rise? (3 steps) |
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Definition
1.hydrogen bonds are broken
2.crystalline collapses
3.Molecules are free to slip closer together |
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Term
| When is water the densest? |
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Definition
| 4C- then begins to expand as the molecules move faster |
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Term
| Why is the ability of ice to float so important? |
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Definition
| If it sank all bodies of water would become frozen solid and during the summer only the upper inches would thaw |
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Term
| What does floating ice due to the liquid below it? |
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Definition
| it insulates the liquid water and prvents it from cooling. |
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Term
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Definition
| Homogenous mixture of two or more substances |
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Term
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Definition
| substance that is dissolved |
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Term
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Definition
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Term
| What is an aqeuous solution? |
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Definition
| One in which water is the solvent |
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Term
| Why is water close to but not a universal solvent? |
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Definition
| It if it were in could not be stored in any container, including our cells. |
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Term
| Explain what NaCl is and how it is dissovled in water (4 steps and result). |
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Definition
NaCl= ionic compound
1. Na and Cl ions aer exposed to solvent
2. Ions and water molecules have a mutual affinity
-O attracted to Na cation
-H attracted to Cl anion
3. Water molecules surround ions and shield one from another
4. This forms a hydration shell
Result- homogenous mixture |
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Term
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Definition
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Term
| Are proteins water soluable? |
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Definition
| If ionic/polar regions are on the surface |
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Term
| What are some examples of fluids that many polar molecules are dissolved in? (3) |
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Definition
| Blood, plant sap, cytoplasm of cells |
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Term
| Can hydrophilic be used to describe a substance even if it is not dissolved? |
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Definition
| Yes- the molecules may be too large for example |
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Term
| What is an example of a hydrophilic substance that absorbs water without disolving and how does it do so? |
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Definition
| cotton- cellulos has regions of partial positive and negative charges- water adheres to the cellulose fibers |
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Term
| What is present in the Xylem walls that makes them hydrophilic? |
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Definition
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Term
| What type of substance repel water? |
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Definition
| non ionic and non polar substances |
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Term
| Why is vegetable oil hydrophobic? |
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Definition
| The bonds between C and H in vegetable oil are non polar bonds that do not share electrons equally |
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Term
| Are cell membranes hydrophobic or hydrophilic? Why? |
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Definition
| Hydrophobic- molecules related to oil are major ingredients of cell memebranes |
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Term
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Definition
| The number of grams of a substance that equals its molecular weight in daltons and contains avagadro's number |
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|
Term
| What is avagadros number? |
|
Definition
| The number of molecules in a mole 6.02 x 10^23 |
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Term
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Definition
| The number of moles of solute per liter or solution |
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Term
| Why is measuring in moles convient for scientists working in the laboratory? |
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Definition
| It allows them to combine substances in fixed ratios of molecules |
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Term
| What happens when a water molecule dissociates? |
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Definition
| The H atom shared by two water molecules shifts from one molecule to another, leaving its electron behind |
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Term
| What is actually transferred when water dissociates? |
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Definition
| A hydrogen Ion (since the hydrogen leaves its electron behind) which is a single proton with a charge of +1 |
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Term
| What happens to the molecule left behind when water dissociates? |
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Definition
| It becomes an OH ion with a charge of -1 since it lost a proton |
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Term
| What does the molecule that dissociates from water bind to and what does it form? |
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Definition
| to the other water molecule making an hydronium ion (H30)+ |
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Term
| What is the equation for the dissociation of water |
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Definition
| H20 (double arrows) H+ + OH- |
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Term
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Definition
| Water in which h+ and OH- are equal (onlye one molecule in every 554 million is dissociated) |
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Term
| How do the concentration of water molecules compared to teh contration of H and OH ions compare when an equilibrium is achieved with the dissociation of water? |
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Definition
| The concentration of water molecules greatly exceeds the number of ions |
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Term
| What do changes in the concentration of H and OH do to cells? |
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Definition
| They affects cells proteins |
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Term
|
Definition
| Increase the H+ concentration in a solution |
|
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Term
|
Definition
| decrease the H+ concentration in a solution |
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Term
| How do bases do "what they do" (3 ways) |
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Definition
1. some directly accept H+ (ex: NH3 ammonia vs. NH4 ammonium)
2.dissociate to form OH ions which comebine with H in solution to form water
3. more OH then H
2. |
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Term
| What is a weak acid/ weak base? |
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Definition
| acids and bases that do not dissociate completely; the reactions are reversible |
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Term
| How do you find the PH of a number? |
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Definition
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Term
| A number that is above 7 on the PH scale is a ____________. A number that is below 7 on the PH scale is a _________. |
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Definition
Acid- More H
Base- More OH |
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Term
| What does each PH unit represent? |
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Definition
| A tenfold difference in H and OH concentration (ex: a PH of 6 vs a PH of 8 =10 x 10) |
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Term
| What range are most biological fluids found in? |
|
Definition
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|
Term
| What is the product in any solution of the H and OH concentrations? |
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Definition
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|
Term
| What happens to PH has H increases? |
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Definition
|
|
Term
| What is the internal PH of most living cells? |
|
Definition
|
|
Term
|
Definition
| Allow biolgoical fluids to resist changes in PH when acids/bases are introduced |
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Term
| What is the PH of human blood and when is it deadly? |
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Definition
| PH= 7.4. If it drops to 7 or raises to 7.8 it is deadly |
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|
Term
| What do buffers do when H ions are in excess? |
|
Definition
|
|
Term
| What do buffers do when H ions in a solution are depleted? |
|
Definition
|
|
Term
| What acts as a buffer to blood? |
|
Definition
|
|
Term
| What does carbonic acid dissociate to yield? |
|
Definition
| Bicarbonate ion (HCO3-) and Hydrogen ion |
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|
Term
| What happens if the PH of blood drops? |
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Definition
| Bicarbonate ion acts as a base and removes H+ |
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|
Term
| What happens if the PH of blood raises? |
|
Definition
| Carbonic acid dissociates replenishing H |
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|
Term
| What is a weak acid and base pair called? |
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Definition
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|
Term
| Acid precipitation is precipitation with a PH lower than... |
|
Definition
|
|
Term
| What two compounds cause acid precipitation? |
|
Definition
| Sulfur oxides and nitrogen oxides |
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|
Term
| What thing causes acid precipiation? |
|
Definition
| 1. burning of fossil fuels- electrical power plants are the biggest users |
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|
Term
| What do tall smokestacks do? |
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Definition
| reduce local pollution but wind carries it to other places |
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Term
| When is the effects of acid rain most pronounced? Why? |
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Definition
| the spring (when the snow melts) b/c all acid accumulates in bodies of water at the same time |
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|
Term
| When does the acid surge effect fish? |
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Definition
| It effects them when they are reproducing |
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|
Term
| What does acid precipitation do to the soil? |
|
Definition
| Affects solubility of soil minerals |
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|
Term
| What does acid rain do to Ca, Mg, and Al? And what as this caused? |
|
Definition
It washes away Ca and Mg.
It increases the solubility of Al which is a toxic.
It has casues a decline in European forests and some in North America. |
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