college bio: chapter 2 smartbook
the kidneys can help organisms cope with changes in pH by
- secreting alkaline compounds into the bloodstream - secreting acidic compounds into the bloodstream - transferring hydrogen ions from the fluids of the body into the urine
if 3 grams of sodium chloride are dissolved in enough water to make 12 liters, what is the concentration of the solution?
.25g/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
arrange the following terms in order of pH, starting with the lowest pH at the top: alkaline, acidic, neutral
1. acidic 2. neutral 3. alkaline
put 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
1. the gaseous state 2. the liquid state 3. the solid state
when water freezes:
1. water molecules are packed into a less dense formation 2. the rate of hydrogen bond breakage flows 3. the H₂O molecules in ice are in a much more orderly arrangement than in the liquid state
rank each state of water in order of increasing density, starting with the least dense
1. water vapor 2. ice 3. liquid water
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
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⁺, OH⁻
a base will release ___ ions when dissolved in water
OH⁻
in pure water, what are the concentrations of H⁺ and OH⁻ ions each
[H⁺] = 10⁻⁷ M, [OH⁻] = 10⁻⁷ M
which of the following contributes to water's stability in a liquid state
a high heat of fusion, a high heat of vaporization
a substance that relates hydrogen ions into 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:
alkaline
a substance that absorbs hydrogen ions in a solution is called a
base
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 the loss of water
what type of compound minimizes pH fluctuations in the fluids of living organisms
buffer
which of the following mechanisms help organisms to regulate their internal pH
buffers, elimination of H⁺ in 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 natural surfaces is known as _______
cohesion, adhesion
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 solutions
concentration
the addition of solutes to water will
decrease its freezing point, increase its boiling point
because exercise produces lactic acid, it may:
decrease the pH of body fluids
ice floats in liquid water because ice has a lower _____ than liquid water
density
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
the ability of an atom to attract electrons in a bond with another atom is termed its
electronegativity
compared with liquid water, ice has
greater hydrogen bonds between individual water molecules, a more orderly arrangement of water molecules
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
when water is heated, the rate at which _____ bonds break increases, and water molecules are covered to the _____ state
hydrogen, gaseous
which molecules are predicted to easily dissolve in water
ions that carry full electric charges, carbohydrates that contain -OH groups
what property of water makes it a good solvent
its ability to form hydrogen bonds
which component of humans has the greatest percent of water
lungs
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
water has a high heat of fusion. this means that
much energy must be withdrawn to cause water to change from a liquid state to solid
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
nonpolar
what type of bonds are most likely to be found in a hydrophobic molecule
nonpolar covalent
colligative properties depend on the _____ dissolved in a solution
number of particles
the polar groups of a micelle are oriented toward the _____, while the non polar groups are oriented towards the _______
outside, inside
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
molecules are likely to dissolve easily in water if they contain what type of bonds
polar covalent bonds, ionic bons
amphipathic molecules have both _____ regions and ______ regions
polar, nonpolar
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
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
a solution is composed of ____ dissolved in a ______
solutes, solvent
solutes dissolved in a solvent form a
solution
a liquid that can dissolve substances is known as a
solvent
hydrochloric acid is called a ____ acid because it almost completely dissociates into H⁺ and Cl⁻ when added to water
strong
what is the heat of fusion of a substance
the amount of energy released when 1 mole of the substance is covered from liquid to solid
define heat of vaporization
the heat energy required to convert 1 mold 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 nonpolar region
what is the molarity of a solution
the number of moles of solute in 1 L
what happens to the pH of a solution when H⁺ ions are added to it
the pH decreases
in a micelle, which portion of the amphipathic molecules are oriented towards the surface of the sphere
the polar region
the molecular mass of a molecule is equal to
the sum of the atomic masses of all atoms in one molecule
describe hydrophilic molecules
they are soluble in water
which of the following statements describe hydrophilic molecules
they are soluble in water
an aqueous solution is one in which the solvent is
water
carbonic acid is called a ____ acid because some of it remains in the H₂CO₃ state when dissolved in water
weak
