Chapter 2 Water and pH

entire alkaline range of pH scale

any pH value above 7

cohesive

because polar molecules attract each other, water is said to be ______

releasing, absorbing

buffer stabilize the pH of solutions by ______ hydrogen ions when a base is added and ____ hydrogen ions when an acid is added

H+, higher

stronger bases have lower concentrations of _____ ions and therefore have a ______ pH

hydrophilic, hydrophobic

substances that attract water are called _____ while substances that repel water are called _____

hydrogen

the attraction between the partially negative oxygen atom of one water molecule and the partially positive hydrogen atom of another water molecule is called a _______ bond

adhesion

the attraction of water to other polar substances

-1

the charge of a hydroxide ion

two single polar covalent bonds

the molecule shown in the bohr model and ball-and-stick model are held together by which bond?

hydrogen

the relatively weak, but numerous ______ bonds that form between a water molecule and other molecules

oxygen, hydrogen

water carried two partial negative charges on the _____ atom and and two partial charges, one on each _____ atom

negative, positive

water carries two partial ______ charges on the oxygen atom and two partial _____ charges, one on each hydrogen atom

polar covalent bonds

water consists of one oxygen atom joined to two hydrogen atoms by two single....

hydrogen bonds

water has a high specific heat Because a large input of thermal energy is needed to break the many _____ ______ that restrict the movement of individual water molecules

they are attracted to eachother

water is cohesive. which describes this feature of water molecules?

Hydrophobic molecules and nonpolar molecules

water tends to repel or exclude what molecules?

water

what do the bohr model and ball-and-stick model represent?

it is attracted to other polar molecules and ions

what does it mean when they say water is adhesive?

water, fructose

when 1 g of fructose is dissolved in 500 mL of water ______ is the solvent and ______ is the solute

solute, solvent

when 1 g of sugar is dissolved in 500 mL of water the sugar is called the _____ and water is called the ____

The [H+] increases 100 fold

when the pH of a solution falls by 2,

the [H+] increases 100-fold

when the pH of a solution falls by 2....

the [H+] decreases 10-fold

when the pH of a solution rises by 1 which of the following happens

the amount of energy needed to change 1 g of water from a liquid to a gas

which of the following is the definition of the heat of vaporization of water?

water

which of the following molecules is likely to have the highest specific heat and the highest heat of vaporization

Because a large input of thermal energy is required to break the many hydrogen bonds between individual water molecules

why does water have very high specific heat?

As the movement of water molecules slows down when liquid water changes to ice hydrogen bonds form that space the molecules relatively far apart

why is solid water less dense than liquid water?

lowers [H+] and increases the pH when it dissociates in water

a base is a substance that

water

A _______ molecule can break apart to form a positive hydrogen ion and a negative hydroxide ion

+1

A hydrogen ion form during the dissociation of water has what charge?

One positive hydrogen ion and one negative hydroxide ion

A single water molecule can spontaneously break apart to form.....

acid

A substance that increases [H+] and decreases PH when it dissociate in water

Water molecules in ice are locked into a crystal like lattice do to hydrogen bonds making ice less dense and liquid

How is the arrangement of water molecules related to it's density

Heat of vaporization

The amount of energy required to change 1 g of a substance from a liquid to a gas is called

The negative a logarithm of the hydrogen ion concentration in the solution

The pH of a solution is defined as

higher, lower

The stronger an acid is the ______ its concentration of hydrogen ions and the ____ its pH

H+, OH

The stronger an acid is the higher its concentration of ______ ions and the lower its concentration of _____ ions

covalent

Water consists of one oxygen atom joined to two hydrogen atoms by what type of bonds

bicarbonate removes H+ from the blood

What an acid is added to the blood how does the carbonic acid/bicarbonate buffer work to stabilize pH

it decreases the solutions pH by releasing protons in the solution

What an acid is dissolved in water how does it change the solutions PH

carbonic acid releases H+ into the blood

When a base is added to the blood how does the carbonic acid/bicarbonate buffer work to stabilize pH

Hydrophobic exclusion

Which property of water strongly affects the overall shape of many biological molecules such as protein and DNA

hydrophobic exclusion

consider a large protein molecule that has some parts that are highly hydrophobic. when placed in a water solution the protein folds in a globular shape such that all the hydrophobic portions are inside the molecules away from water. what is this an example of?

any pH below 7

entire acidic range of pH scale

they play a key role in determining the properties of water and they help maintain the structure of DNA and proteins

hydrogen bonds are important for which reasons?

repel water, assume shapes that minimize contact with water, and aggregate together when mixed with water in order to minimize contact with water

hydrophobic substances tend to do what?

higher heat of vaporization and a higher specific heat

molecules that are more polar tend to have which of the following characteristics?