Bio Exam 1 Ch. 3
how many molecules of glucose (C6H12O6 molecular mass=180 daltons) would be present in 90 grams of glucose
(90/180) x 6.02 x 10^23
identical heat lamps are arranged to shine on identical containers of water and methanol (wood alcohol) so that each liquid absorbs the same amount of energy minute by minute. the covalent bonds of methanol molecules are non polar so there are o hydrogen bonds among methanol molecules. which of the following graphs correctly describes what will happen to the temperature of the water and methanol
(graph with dotted line above solid line, both going to the right diagonally)
a small birthday candle is weighed then lighted and placed beneath a metal can containing 100 mL of water. careful record are kept as the temperature of the water rises. data from this experiment are shown on the graph. what amount of heat energy is released in the burning of candle wax
.5 kilocalories per gram of wax burned
when an ionic compound such as sodium chloride is placed in water the component atoms of the NaCl crystal dissociate into individual sodium ions and chloride ions. in conrast the atoms of covalently bonded molecules do not generally dissociate when placed in aqueous solution. which of the following solutions would be expected to contain the greatest number of solute particles
1 L of .5 M NaCl
assume that acid rain has lowered the pH of a particular lake to pH 4. what is the hydroxyl ion concentration of this lake
1 x 10^-10 mol of hydroxyl ion per liter of lake water
a slice of pizza has 500kcal. if we could burn the pizza ad use all the heat to warm a 50 L container of cold water what would be the approximate increase in the temperature of the water
10 degrees celsius
the nutritional information on a cereal bod shows that one serving of a dry cereal has 200 kilocalories. if one were to burn one serving of the cereal the amount of heat given off would be sufficient to raise the temperature of 20kg of water how many degrees celsius
10 degrees celsius
one liter of a solution of pH 2 has how many more hydrogen ions H+ than 1 L of a solution of pH 6
10, 000 times more
equal volumes (5mL) of vinegar from a freshly opened bottle are added to each of the following solutions. after complete mixing which of the mixtures will have the highest pH
100 mL of household cleanser containing .5 M ammonia
one liter of a solution of pH 9 has how many more hydroxyl ions (OH-) than 1 L of a solution of pH 4
100,000 times more
a dietary calorie equals 1 kilocalorie. which of the following statements correctly defines 1 kilocalorie
1000 calories or the amount of heat required to raise the temperature of 1kg of water by 1 degree celsius
measurements show that the pH of a particular lake is 4. what is the hydroxide ion concentration of the lake
10^-10 M
measurements show that the pH of a particular lake is 4. what is the hydrogen ion concentration of the lake
10^-4 M
what is the hydrogen ion (H+) concentration of a solution of pH 8
10^-8 M
how many grams of the compound in the figure above would be required to make 2.5 L of a 1 M solution (carbon=12, oxygen=16, hydrogen=1)
150
how many grams of the compound in the figure above would be required to make 1 L of a .5 M solution (carbon=12, oxygen=16, hydrogen=1)
30
the molecular weight of water is 18 daltons. what is the molarity of 1 liter of pure water
55.6 M
you have a freshly prepared .1 M solution of glucose in water. each liter of this solution contains how many glucose molecules
6.02 x 10^22
you have a freshly prepared 1 M solution of glucose in water. you carefully pour out a 100 ml sample of that solution. how many glucose molecules are included in that 100mL sample
6.02 x 10^22
how many molecules of glycerol (C3H8O3 molecular mass=92) would be present in 1 L of a 1 M glycerol solution
6.02 x 10^23
how many grams would be equal to 1 mol of the compound shown in the figure above (carbon=12, oxygen=16, hydrogen=1)
60
how many grams of acetic acid (C2H4O2) would you use to make 10 L of a .1 M aqueous solution of acetic acid
60g
you have two beakers. one contains a solution of HCL at pH=10. the other contains a solution of NaOH at pH=13. into a third beaker you slowly and cautiously pour 20mL of the HCl and 20 mL of the NaOH. after complete stirring the pH of the mixture will be
7
you have two beakers. one contains pure water the other contains pure methanol (wood alcohol) the covalent bonds of methanol molecules are non polar so there are no hydrogen bonds among methanol molecules. you pour crystals of table salt (NaCl) into each beaker. predict what will happen
NaCl crystals will dissolve in either water or methanol
which of the following ionizes completely in solution and is considered to be a strong base (alkali)
NaOH
one of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3) carbonic acid is a wear acid that when placed in an aqueous solution dissociates into a bicarbonate ion (HCO3- and a hydrogen ion (H+)) thus (equation) if the pH of the blood increases one would expect
a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-
the slight negative charge at one end of one water molecule is attracted to the slight positive share of another water molecule. what is this attraction called
a hydrogen bond
which of the following effects is produced by the high surface tension of water
a water strider can walk across the surface of a small pond
liquid water's high specific heat is mainly a consequence of the
absorption and release of heat when hydrogen bonds break and form
a given solution contains .0001 (10^-4) moles of hydrogen ions (H+) per liter. which of the following best describes this solution
acidic: will give H+ to weak acids, but accept H+ from strong acids
how would acidification of seawater affect marine organisms
acidification would decrease dissolved carbonate concentrations and hinder growth of corals and shell building animals
carbon dioxide (CO2) is readily soluble in water according to the equation CO2+H2O <-> H2CO3. carbonic acid (H2CO3) is a weak acid. respiring cells release CO2 into the bloodstream. what will be the effect on pH of blood as that blood first comes in contact with respiring cells
blood pH will decrease slightly
one mole of glucose is
both 180 grams of glucose and 6.02 x 10^23 moles of glucose
buffers are substances that help resist shifts in pH by
both donating H+ to a solution when bases are added, and accepting H+ when acids are added
one idea to mitigate the effects of burning fossil fuels on atmospheric CO2 concentrations is to pipe liquid CO2 into the ocean at depths of 2500 feet or greater. at the high pressures at such depths CO2 is heavier than water. what potential effects might result from implementing such a scheme
both increased acidity of the deep waters and changes in the growth of bottom dwelling organisms with calcium carbonate shells
water molecules are able to form hydrogen bonds with
compounds that have polar covalent bonds
if the pH of a solution is decreased from 9 to 8 it means that the
concentration of H+ has increased tenfold (10x) and the concentration of OH- has decreased to one tenth what they were at pH 9
if the pH of a solution is increased from pH 5 to pH 7 it means that the
concentration of OH- is 100 times greater than what it was at pH 5
the molar mass of glucose is 180 g/mol. which of the following procedures should you carry out to make a 1 M solution of glucose
dissolve 180 g of glucose in .8 L of water, and then add more water until the total volume of the solution is 1 L
the molar mass of glucose (C6H12O6) is 180 g/mol. which of the following procedures should you carry out to make a .5 M solution of glucose
dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L
which of the following solutions would require the greatest amount of base to be added to bring the solution to neutral pH
gastric juice at pH 2
which type of bond must be broken for water to vaporize
hydrogen bonds
the bonds that are broken when water vaporizes are
hydrogen bonds between water molecules
why does ice float in liquid water
hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water
a strong acid like HCL
ionizes completely in an aqueous solution
a .01 M solution of a substance has a pH of 2. what can you conclude about this substance
it is a strong acid that ionizes completely in water
which of the following takes place as an ice cube cools a drink
kinetic energy in the drink decreases
a solution contains .0000001 (10^-7) moles of hydroxyl ions (OH-) per liter. which of the following best describes this solution
neutral
hydrophobic substances such as vegetable oil are
nonpolar substances that repel water molecules
we can be sure that a mole of table sugar and a mole of vitamin c are equal in their
number of molecules
what is the pH of a 1 millimolar NaOH solution
pH 11
what is the pH of a solution with a hydroxyl ion (OH-) concentration of 10^-12M
pH 2
in a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by
polar covalent bonds
based on your knowledge of the polarity of water molecules the volute molecule depicted here is most likely
positively charged
increased atmospheric CO2 concentrations might have what effect on seawater
seawater will become more acidic and carbonate concentrations will decrease
one of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3) carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+) thus (equation) if the pH of the blood drops, one would expect
the HCO3- to act as a base and remove excess H+ with the formation of H2CO3-
many mammals control their body temperature by sweating. which property of water is most directly responsible of the ability of sweat to lower body temperature
the absorption of heat by the breaking of hydrogen bonds
if a solution has a pH of 7 this means that
the concentration of H+ ions in the water equals the concentration of OH- ions in the water
if the cytoplasm of a cell is at pH 7 and the mitochondrial matrix is at pH 8 this means that
the concentration of H+ ions is tenfold higher in the cytoplasm than in the mitochondrial matrix
consider two solutions; solution x has a pH of 4; solution y has a pH of 7. from this information we can reasonably conclude that
the concentration of hydrogen ions in solution x is 1000 times as great as the concentration of hydrogen ions in solution y
the partial negative charge in a molecule of water occurs because
the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus
a beaker contains 100 mL of NaOH solution at pH = 13. a technician carefully pours into the beaker 10 mL of HCL at pH =1. which of the following statements correctly describes the results of this mixing
the pH of the beaker's contents falls
temperature usually increases when water condenses. which behavior of water is most directly responsible for this phenomenon
the release of heat by the formation of hydrogen bonds
why does evaporation of water from a surface cause cooling of the surface
the water molecules with the most heat energy evaporate more readily
which of the following statements is true about buffer solutions
they maintain a relatively constant pH when either acids or bases are added to them
research indicates that acid precipitation can damage living organisms by
washing away certain mineral ions that help buffer soil solution and are essential nutrients for plant growth
which of the following is a hydrophobic material
wax
sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. compared to water molecules, molecules of H2S
will not form hydrogen bonds with each other
