Bio Exam 1 CH. 3
Rank, from low to high, the pH of blood, stomach acid, and urine.
stomach acid, urine, blood
Why isn't this insect drowning?
surface tension
Electronegativity is
the attraction of an atom for the electrons in a covalent bond. The more electronegative an atom is, the more strongly it pulls shared electrons toward itself.
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 polar covalent bond between two atoms results from
two atoms that do not have similar electronegativities.
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 _____.
1 calorie
When an ionic compound such as sodium chloride (NaCl) is placed in water, the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) 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 (molecules or ions)?
1 liter of 1.0 M NaCl
A pH of 6 is how many times more acidic than a pH of 9?
1,000 (10x10x10)
The concentration of the appetite-regulating hormone ghrelin is about 1.3 × 10-10 M in the blood of a fasting person. How many molecules of ghrelin are in 1 L of blood?
7.8 × 10^13 A liter of blood would contain 7.8 × 1013 molecules of ghrelin (1.3 × 10-10 moles per liter × 6.02 × 1023 molecules per mole).
Which of the following can be attributed to water's high specific heat?
A lake heats up more slowly than the air around it.
Which of these bonds is weakest?
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.
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.
All of the following statements help to explain why water molecules form hydrogen bonds except: There is a partial positive charge on each hydrogen atom and two partial negative charges on the oxygen atom in a water molecule. The electrons spend more time around the oxygen atom because oxygen is more electronegative than hydrogen. Attractions form between opposite partial charges. Water is an electronegative molecule.
Water is an electronegative molecule. Molecules can't be electronegative.
the more h+ ions, the more _ the solution
acidic
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
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
Water molecules can form hydrogen bonds with _____.
compounds that have polar covalent bonds
The tendency of an atom to pull electrons toward itself is referred to as its _____.
electronegativity
Each water molecule is joined to _____ other water molecules by ____ bonds.
four ... hydrogen
Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's _____.
high specific heat
The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. What is this attraction called?
hydrogen bond
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 The polarity of a water molecule allows the oxygen of one water molecule to bond weakly to the hydrogen of another water molecule.
What is the arrow pointing to? +
hydrogen ion. (The arrow is indicating a single proton, a hydrogen ion H+)
In a neutral solution the concentration of _____.
hydrogen ions is equal to the concentration of hydroxide ions
What is the arrow pointing to? -
hydroxide ion The arrow is indicating a hydroxide ion (OH-).
As the [H3O+] of the solution decreases, the [OH-] ________.
increases and thus pH increases
An acid is a substance that _____.
increases the hydrogen ion concentration of an aqueous solution
If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, then the concentration of H+ ions _____.
is 10 times higher in the cytoplasm than in the mitochondrial matrix
A solution contains 0.0000001 (10-7) moles of hydrogen ions [H+] per liter. Which of the following best describes this solution?
neutral
What is the pH of a solution with a hydroxyl ion (OH-) concentration of 10-10 M?
pH 4
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.
In this molecule, what type of bond is found between the oxygen and hydrogens?
polar covalent While oxygen shares electrons with hydrogen, the electrons spend more time with the oxygen than with the hydrogens.
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by _____.
polar covalent bonds
Two moles weigh?
120 (4H, 2C, 2O)
One mole (mol) of glucose (molecular mass = 180 daltons) is ________.
180 grams of glucose
How many grams of the compound in the figure are required to make 1 liter of a 0.5 M solution?
30
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
