BIOL 1107: Test 1
65 Cards in this Set
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molarity
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mol/liters
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polar covalent
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when an atom is bonded to a more electronegative atom, the electrons of the bond are not equally shared
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non-polar covalent
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a covalent bond between two atoms of the same electronegativity (or very close) so the electrons are equally shared
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ionic bond
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when two atoms have a very large difference in electronegativity so the more electronegative one strips the other of its valence electrons, ex. NaCl
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covalent bond
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two atoms share their valence electrons
ex. H2, O2, H2O, CH4
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electronegativity
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the attraction of a particular atom for the electrons of a covalent bond is called its _______.
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what happens when an atom is more electronegative
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the more electronegative an atom is, the more strongly it pulls shared electrons towards itself.
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salts
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made up of ionic bonds (also called ionic compounds)
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hydrogen bond
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a partial positive hydrogen covalently bonded with an electronegative atom is allowed to noncovalently bond with another electronegative molecule nearby
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van der wals
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ever changing regions of a molecule of positive and negative charges that enable all atoms and molecules to stick together
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why is molecular shape crucial to biology?
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it determines how biological molecules recognize and respond to one another with specificity. biological molecules often bind temporarily to one another by forming weak bonds but can only do this if their shapes are complimentary.
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why does the structure H-C=C-H fail to make sense chemically?`
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each carbon only has three covalent bonds instead of four
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what hold the atoms together in a crystal of magnesium chloride (MgCl2)?
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the attraction between oppositely charged ions, forming ionic bonds
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chemical reactions
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the making a breaking of chemical bonds, leading to changes in the composition of matter
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reactants + reaction --> products
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N/A
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photosynthesis
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takes place within the cells of green plant tissues
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chemical equilibrium
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the point at which the reactions offset one another exactly - reactions are still going on but with no net effect on the concentration
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what is one factor that effects the rate of a reaction?
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concentration of reactions - the greater the concentration of reactant molecules, the more frequently they collide with one another and have an opportunity to react and form products.
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at equilibrium which chemical reaction occurs faster at equilibrium: the formations of products from reactants or reactants from products?
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at equilibrium, the formation of products from reactants is EQUAL to reactants from products - neither is faster than the other
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cellular respiration
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the opposite of photosynthesis - the products of photosynthesis are the reactants and the reactants of photosynthesis + energy are the producsts
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molecule
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two or more covalently bonded atoms
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how do weak bonds help a molecule?
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they reinforce the structure and help the molecules stick together
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what determines a molecules shape?
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the positions of the atoms' valence orbitals
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what is the basis for the recognition of one biological molecule by another?
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shape
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in terms of electron sharing what is the difference between nonpolar covalent, polar covalent and ion forming
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nonpolar covalent - shares electrons equally (same electronegativity)
polar covalent - the shared electrons are pulled towards the more electronegative atom
ion forming - the shared electron is completely removed and adhered to the more electronegative atom
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if more reactant was added to a reaction that is already at equilibrium, what happens to the chemical equilibrium?
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when more reactant is added to a reaction already at equilibrium, it will increase the concentration of products as they are converted to products... soon equilibrium will be reached again and the ratio will be back to where it was
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trace element
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an element absolutely needed for life but required in extremely minute amounts - ex: iron and zinc
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how is 31P different than 32P (the radioactive isotope)?
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32P has one more neutron
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where does the reactivity of an atom arise from?
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the existence of unpaired electrons in the valence shell
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when an atom has more electrons than protons it is a...
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anion
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8 protons, 10 neutrons, 8 electrons represents what atom?
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oxygen
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what is the only substance to exist in all three states of matter in a natural environment?
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water
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what kind of molecule is water? what kind of bonds does it have?
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water is a polar molecule with nonpolar covalent bonds (because O is more electronegative than H)
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describe the hydrogen bonds in water in the liquid stage
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the h-bonds in the liquid stage are very fragile breaking and forming frequently
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what would be the effect on the properties of the water molecule if oxygen and hydrogen had equal electronegativity?
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if O and H had equal electronegativity the water molecules would not be polar and would not be able to form hydrogen bonds with eachother
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cohesion
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when a substance is held together by linkages (like hydrogen bonds in water)
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aqueous solution
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a solution where water is the solvant
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hydrogen ion (H+)
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the hydrogen that detaches from a water molecule
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when a water molecule loses a hydrogen ion, it becomes a...
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hydroxide ion (OH-)
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when a hydrogen ion attaches to a water molecule, it becomes a ...
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hydronium ion (H3O+)
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is the dissociation of water molecules frequent?
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the dissociation of water molecules (the concentration of H+ and OH- ions) is much less than that of the whole water molecules in pure water at room temp.
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in pure water what is the ratio of H+ to OH- ions?
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they are equal
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how does pH affect a cell?
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it can affect its proteins and other complex molecules
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acid
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a substance that increases the hydrogen ion concentration of a solution... ex: HCl is added to water, the H ions dissociate from the Cl ions
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base
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a substance that reduces the hydrogen ion concentration... some bases reduce acidity by accepting H+ ions directly (NH3 + H+ = NH4) and some reduce acidity add OH- to the substance to become H2O.
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in any aqueous solution at 25 degrees C, the product of the H+ and OH- ions concentrations is...
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[H+][OH-] = 10^-14
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what is the pH concentration of a neutral solution at room temperature?
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[H+] = 10^-7
[OH-] = 10^-7
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as pH declines, concentration....
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increases
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buffers
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in biological fluids can resist change in pH - a buffer consists of an acid base pair that combines reversibly with hydrogen ions
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compared with a basic solution at pH = 9, the same volume of an acidic solution at pH = 4 has ___ times as many hydrogen ions.
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10^5 or 100,000
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what is the pH of 0.01 M HCl?
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[H+] = 0.01 M
= 10^-2 M
= pH 2
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given a liter of pure water and a liter solution of acetic acid, what would happen to the pH if you added 0.01 mol of a strong acid to each?
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the pH of the water should decrease from 7 to about 2 and the pH of the acetic acid solution will decrease only a small amount because the CH3COO- molecules will accept the added H+ molecules become CH3COOH
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the bonds broken when water vaporizes are.....
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hydrogen bonds between water molecules (in the gas state, the water molecules move around to quickly to bond together)
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which of the following is a hydrophobic matter:
paper, table salt, wax, sugar, pasta
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wax
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we can be sure that a mole of table sugar and mole of vitamin C are equal in their....
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number of molecules (avagadro's number = x10^23)
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measurements show that the pH of a particular lake is 4.0 - what is the hydrogen ion concentration of the lake?
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[H+] = 10^-4 M
this a fairly acidic lake, pure water is pH 7
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what is the hydroxide ion concentration of the lake with a pH of 4.0?
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[OH-] = 10^-10
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1 kilocalorie = __ joules
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4184 joules
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1 liter = __ kg
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1 kg`
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a slice of pizza has 500 kcal. if we could burn the pizza and use all the heat to warm a 50 L container of cold water, what would be the approx. increase in the temperature of the water? (1L = 1kg)
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10 degrees Celcius
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how many grams of acetic acid (C2H4O2) would you use to make 10 L of a 0.1 aqueous solution of acetic acid? (note: the atomic masses, in daultons are approx. 12 for carbon, 1 for hydrogen, and 16 for oxygen).
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60 g
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why to farmers spray water on their crops before and overnight freeze? how does this protect the plants?
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water has an incredibly high heat of fusion - that is water will hang out at 0C and it takes a long time for the water to freeze. A high heat of fusion means that, even if the temperature of the air changes a lot, water will shelter you from those changes and provide a pretty stable envir…
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what do proteins, DNA, carbohydrates and other molecules that distinguish living matter have in common?
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made up of carbon atoms bonded to one another - organic chemistry
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in organic molecules is there a cuttoff to how many carbons a molecule can have?
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no they range from simple methane (CH4) to complex molecules with an unknown number of carbons
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what are the major elements of life?
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C, H, O, N, S and P
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BIOL 1107: Test 4