Chapters 3 & 4 Flashcards
Water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as _____.
hydrogen bonds
Many of water’s emergent properties, such as its cohesion, its high specific heat, and its high heat of vaporization, result from the fact that water molecules _____.
are attracted to each other by partial negative and positive charges on the oxygen and hydrogen atoms, respectively
The amount of energy that must be absorbed or lost to raise or lower the temperature of 1 g of liquid water by 1°C _____.
is 1 calorie
Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water’s _____.
high specific heat
Water has a high specific heat, meaning that
a relatively large amount of heat must be added or removed in order to get the temperature of the water to change significantly.
The specific heat of liquid water is
1 cal/g/°C
The formation of hydrogen bonds between the positive and negative regions of different water molecules accounts for
most of water’s unique properties.
The polarity of a water molecule allows the oxygen of one water molecule to
bond weakly to the hydrogen of another water molecule.
Sodas typically contain sugar, flavorings, coloring agents, and carbon dioxide dissolved in water. The best term to describe this mixture would be _____.
an aqueous solution
If the molecular mass of a carbon atom is 12, the mass of a hydrogen atom is 1, and the mass of an oxygen atom is 16 daltons, how many molecules does one mole of table sugar (sucrose; C12H22O11) contain?
6.02 x 10^23
the number of molecules in one mole of any substance is
6.02 x 10^23
An acid is a substance that _____.
increases the hydrogen ion concentration of an aqueous solution
As an acid dissociates, it
donates a hydrogen ion to the solution
A pH of 6 is how many times more acidic than a pH of 9?
1,000
A pH of 6 is
10 times more acidic than 7, which is 10 times more acidic than 8, which is 10 times more acidic than 9. 10 x 10 x 10 = 1,000.
A buffer
resists change in pH by accepting hydrogen ions when acids are added to the solution and donating hydrogen ions when bases are added.
Buffers minimize the change in the _____ of a solution.
pH
Most acid precipitation results from the combination of _____ with water in the atmosphere, forming strong acids that fall with rain or snow.
sulfur oxides and nitrogen oxides.
These compounds react with water in the atmosphere to form sulfuric acid and nitric acid.
Most organic compounds contain carbon and _____.
hydrogen
The experiments of Wöhler, Kolbe, Miller, and other chemists invalidated the concept of vitalism by demonstrating that _____.
organic molecules could be produced apart from living organisms using inorganic materials
Vitalism gave way to mechanism, the view that _____.
physical and chemical laws govern living systems
Living things are subject to physical and chemical laws. They do not exist outside of them.
The large diversity of shapes of biological molecules is possible because of the extensive presence of _____ in the molecules.
carbon
With four electrons to share, carbon-based molecules can be multibranching and three-dimensionally variable.
Which of the following is a hydrocarbon?
C3H8
(This is a typical hydrocarbon with single covalent bonds; the number of hydrogen atoms is equal to two times the number of carbon atoms plus 2.)
Molecules that have the same chemical formula (same numbers of each atom) but different three-dimensional shapes are called _____.
isomers
Isomers of carbon compounds can arise in several different ways.
Cis-trans isomers
differ in their spatial arrangement around inflexible double bonds.
(Cis-trans isomers maintain the same covalent partnerships, but the atoms may be arranged differently.)
Citric acid makes lemons taste sour. Which of the following is a functional group that would cause a molecule such as citric acid to be acidic?
carboxyl
The carboxyl group can release a hydrogen ion when in solution.
Variations in the reactive properties of different organic molecules are most closely associated with _____.
the presence or absence of functional groups.
Functional groups are the most common participants in
chemical reactions
What functional group is commonly used in cells to transfer energy from one organic molecule to another?
phosphate.
(The addition and release of phosphate groups to and from ADP and ATP is how cells store chemical energy and expend it to accomplish work.)
Each water molecule is joined to _____ other water molecules by ____ bonds.
four … hydrogen
(As can be seen in the illustration on page 1 of the activity titled “The Polarity of Water” a water molecule is joined to four other water molecules by hydrogen bonds.)
The unequal sharing of electrons within a water molecule makes the water molecule _____.
polar
(The electrons spend more time with the oxygen of the water molecule than with the hydrogens of water. Thus, the oxygen has a net negative charge and the hydrogens have a net positive charge.)
The tendency of an atom to pull electrons toward itself is referred to as its _____.
electronegativity
Hydrogen Bonds are weaker than covalent bonds because
they do not involve sharing of electrons, and they are weaker than ionic bonds because they involve the attraction of partial (not full) opposite charges.
The high surface tension of water allows
the insect to remain on the surface.
Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature?
the absorption of heat by the breaking of hydrogen bonds
The bonds that are broken when water vaporizes are
hydrogen bonds between water molecules
Which of the following is a hydrophobic material?
wax
We can be sure that a mole of table sugar and a mole of vitamin C are equal in their
number of molecules
Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?
10^-4 M
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 approximate increase in the temperature of the water? (Note: A liter of cold water weighs about 1 kg.)
10 degrees C
How many grams of acetic acid (C2H4O2) would you use to make 10 L of a 0.1 M aqueous solution of acetic acid? (Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.)
60 g
Organic chemistry is currently defined as
the study of carbon compounds
Which chemical group is most likely to be responsible for an organic molecule behaving as a base?
amino
