College Biology: Chapter 2 Smartbook - The Chemical Basis of Life
if 3 grams of sodium chloride are dissolved in enough water to make 12 liters, what is the concentration of the solution?
0.25 g/L
the molecular mass of glucose is 180g. if 90g of glucose are dissolved in enough water to make 1L, what is the molarity of the solution?
0.5 M
a solution at pH 6 is more acidic than a solution at pH 7 because the concentration of H⁺ (protons) is ___ times higher than that in a solution pH 7
10
each change of one pH unit represents a ___ difference in H⁺ concentration
10-fold
in pure water, the concentrations of H+ and OH- ions are:
10^-7 M each
if a solution has a pH of 8, what is the concentration of protons in the solution?
10^-8 M
the atomic mass of carbon is 12, and the atomic mass of hydrogen is 1. what is the molecular mass of a methane molecule (CH4)?
16
the atomic mass of hydrogen is 1, and the atomic mass of oxygen is 16. what is the molecular mass of a water molecule (H2O)
18
if 1 gram of glucose is dissolved in a total volume of 0.5 L, what is the concentration of the solution?
2 grams per liter
what is the normal pH range of living cells?
6.5-7.8
in humans, water compromises approximately ____ of body weight
60-70%
when water ionizes, it produces what ions?
H+ and OH-
what contributes to waters stability in a liquid state?
a high heat of vaporization, a high heat of fusion
a substance that relates hydrogen ions into a solution is called an?
acid
if you add H+ ions to a solution, it becomes more:
acidic
a solution at pH 5 is said to be ______ because it contains more ______
acidic; H+ ions than OH- ions
with respect to pH, blood in the human body is within a narrow range of values that are considered to be slightly:
akaline
arrange the following solutions in order of increasing proton concentration. the solution with the lowest proton concentration should be placed at the top: neutral akalkine acidic
akaline neutral acidic
Aasolution in which water is the solvent is called a _____ solution.
aqueous
in pure water, what are the concentrations of H⁺ and OH⁻ ions each?
are the concentrations of H⁺ and OH⁻ ions each [H⁺] = 10⁻⁷ M, [OH⁻] = 10⁻⁷ M
a substance that absorbs hydrogen ions in a solution is called a?
base
in animals, what buffer is primarily responsible for maintaining the pH of body fluids?
bicarbonate
a polar covalent bond is created when?
bonded atoms have unequal pull on the shared electron, so that the electron spends more time around one atom than the other
hydrolysis reactions:
break apart molecules via water
what type of compound minimizes pH fluctuations in the fluids of living organisms?
buffers
what mechanisms help organisms to regulate their internal pH?
buffers, elimination of H+ into the urine (via the kidneys)
heat ____ refers to the amount of heat energy required to raise the temperature of an entire object, such as a body of water
capacity
which of the following molecules are predicted to easily dissolve in water?
carbohydrates that contain OH- groups, ions that carry full electric charges
living organisms are mainly composed of which atoms?
carbon, hydrogen, nitrogen, and oxygen
which of the following changes in the physical state of water require the input of energy?
changing from solid to liquid, changing from liquid to gas
the phenomenon of water molecules attracting one another is known as ______ whereas the process of water molecules being attracted to non-neutral surfaces is known as ________
cohesion, adheison
properties of a solution that depend strictly on the total number of dissolved solutes, and not the specific type of solute, are called _____ properties
colligative
properties of a solution that depend strictly on the total number of dissolved solutes, and not the specific type of solute, are called ________ properties
colligative
the amount of solute (in grams) dissolved in a given volume of solution is the solution's:
concetration
the addition of solutes to water will?
decrease its freezing point, increase its boiling point
ice floats in liquid water because ice has a lower ______ than liquid water
density
because exercise produces lactic acid, it may:
descrease the pH of body fluids
select all of the following that describe molecules that only have hydrophobic regions
dissolve well in non polar solvents, contain many non polar covalent bonds, relatively insoluble in water
what describes molecules that only have hydrophobic regions?
dissolve well in non-polar solvents, relatively insoluble in water, contain many non-polar covalent bonds
the ability of an atom to attract electrons in a bond with another atom is termed its?
electronegativity
when water vaporizes at an ordinary temperature, the process is known as?
evaporation
compared with liquid water, ice has?
greater hydrogen bonds between individual water molecules, a more orderly arrangement of water molecules
an amphipathic molecule:
has polar and non-polar regions
compared to a small puddle of water, a lake has?
higher heat capacity, but the same specific heat
hydrochloric acid is considered an acid because it releases _______ ions into solution
hydrogen
the considerable amount of heat it takes to boil water is due to the collective strength of many _____ bonds
hydrogen
water clings to surfaces to which it can form a _______ bond
hydrogen
when water is heated, the rate at which _______ bonds break increases, and water molecules are converted to the ______ state
hydrogen, gaseous
amphipathic molecules have both ______ regions and ______ regions
hydrophillic, hydrophobic
a base will release ____ ions when dissolved in water
hydroxide
which molecules are predicted to easily dissolve in water?
ions that carry electric charges, carbohydrates that contain OH- groups
what property of water makes it a good solvent?
it's ability to form hydrogen bonds
which state of water is the most dense?
liquid
which component of humans has the greatest percent of water?
lungs
when mixed with water, amphipathic molecules may aggregate into spheres called
micelles
when mixed with water, amphipathic molecules may aggregate into spheres called?
micelles
the sum of the atomic masses of all atoms in a molecule is equal to the molecule's _________ mass
molecular
pH is defined as the ____ ____ to the base of 10 of the ___ concentration
negative logarithm, H+
hydrophobic molecules tend to contain many ________ covalent bonds, such as the bond between two carbon atoms or the bond between carbon and hydrogen
non-polar
what type of bonds are most likely to be found in a hydrophobic molecule?
non-polar covalent
colligative properties depend on the _____ dissolved in a solution
number of particles
the ____ of a solution is the negative base 10 logarithm of the H⁺ concentration of the solution
pH
the unequal sharing of electrons between the oxygen and hydrogen atoms within a water molecule makes water a ____ molecule
polar
pure water can ionize into?
positively charged protons (H⁺) and negatively charged hydroxide (OH⁻) ions
acid rain can ____ the pH of water entering the roots of plants
reduce
to freeze water, energy is?
released
what has the lowest freezing temperature? sea water water in an office water cooler lake water sugar water, as in soda
sea water
the kidneys can help organisms cope with changes in pH by?
secreting acidic compounds into the bloodstream, secreting alkaline compounds into the bloodstream, transferring hydrogen ions from the fluids of the body into the urine
the concentration of a liquid is defined as the amount of ________ dissolved in a unit volume of solution
solute
substances dissolved in liquid are known as?
solutes
substances dissolved in liquids are known as?
solutes
solutes dissolved in a solvent form a?
solution
hydrochloric acid is called a ____ acid because it almost completely dissociates into H⁺ and Cl⁻ when added to water
strong
____ is a measure of the attraction between molecules of water at the surface of a liquid due to hydrogen bonding
surface tension
polar covalent O-H bonds in water molecules enable hydrogen bonds to form between water molecules. what properties of water result from hydrogen bond formation?
surface tension, high heat of vaporization, adhesion, high specific heat, cohesion,
what is the heat of fusion of a substance?
the amount of heat energy released when 1 mole of the substance is converted from liquid to solid
place the physical states of water in order based on the intermolecular distances between water molecules. the top position should be the state in which the molecules are the farthest apart: the solid state the liquid state the gaseous state
the gaseous state, the liquid state, the solid state
define heat of vaporization
the heat energy required to convert 1 mole of a substance from liquid to gas
define specific heat
the heat energy required to raise the temperature of 1 gram of a substance by 1 degree celsius
define heat of capacity
the heat energy required to raise the temperature of an entire object
define heat of fusion
the heat energy that must be withdrawn or released from a substance to convert it from liquid to solid
water has a high heat of vaporization because of?
the high number of hydrogen bonds between molecules
what part of an amphipathic molecule would be oriented toward the center of a micelle?
the non-polar region
what is the molarity of a solution?
the number of moles of a solute in 1 liter
what happens to the pH of a solution whenH⁺ ions are added to it
the pH decreases
in a micelle, which portion of the amphipathic molecules are oriented toward the surface of the sphere?
the polar region
when water freezes?
the rate of hydrogen bond breakage slows, water molecules are packed into a less dense formation, the H2O molecules in ice are in a much more orderly arrangement than in the liquid state
the molecular mass of a molecule is equal to
the sum of the atomic masses of all atoms in one molecule
describe hydrophillic molecules
they are soluble in water
what describes hydrophilic molecules?
they're soluble in water
even though it requires energy to change water from a liquid to a gas, some water molecules break their hydrogen bonds at an ordinary temperature (evaporate) by:
vibrating at a higher energy
rank each of the types of water from increasing density, starting with the lease dense state at the top: ice, liquid water, water vapor
water vapor, ice, liquid water
carbonic acid is called a ______ acid because some of it remains in the H2CO3 state when dissolved in water
weak
