Water & pH

Question 1

Cation vs anion

Answer 1

loss of electron, positive charge

Gain of electron, negative charge

Question 2

Polar vs nonpolar covalent bonds

Answer 2

Polar- Electrons are shared unequally, resulting in one atom with a partial positive charge and one with a partial negative charge. Ex: water

Nonpolar- Electrons are shared equally, electronegativities of the 2 atoms are equal. Ex: Carbon and hydrogen

Question 3

Electronegativity trend

Answer 3

Increases as you go right. Increases up.

Question 4

The concentration of hydrogen ions produced by dissociation in pure water is

Answer 4

1 x 10^ -7 M

Question 5

Molarity

Answer 5

Moles of solute per liter of solution (mol/L)

1 mole= 6.02x 10^23

Question 6

Acidic solutions have more __ and less __

Basic solutions have more ___ and less __

Answer 6

Acidic- more H+, less OH-

Basic- More OH-, less H+

Question 7

Solutions are classified as acidic or basic based on their ___ concentration relative to pure water

Answer 7

Hydrogen ion

Question 8

pH stands for

Answer 8

The power of H. How the hydrogen ion concentration of a solution is expressed.

Question 9

Equation for pH

Answer 9

pH = -log [H+]

H+ can either be in the 1x10^x form or M

Question 10

Strong acids or strong bases in water

Answer 10

Completely dissociate. Reaction goes one way. No going back.

Question 11

Weak acids or bases in water

Answer 11

Incompletely dissociate. Can interconvert between acidic and basic forms as conditions change

Question 12

Define an acid and a base

Answer 12

Acid gives away H+. An acid added to an aqueous solution increases the H+ concentration by giving away H+. The freed H+ combines with water molecules to form Hydronium (H3O+)
Bases bind to H+. Bases added to an aqueous solution decreases H+ concentration by binding their lone pair of electrons with H+.

Question 13

HA + H2O H3O+ + A-

Answer 13

Weak acid (HA) + water dissociates into hydronium and a conjugate base.

Question 14

B + H2O BH+ + OH-

Answer 14

Weak base plus water dissociates into a conjugate acid and OH-.

Question 15

Ka (Kb) and pKa

Answer 15

Value used to describe the tendency of compounds to dissociate in water (the dissociation or equilibrium constant).

More comply expressed in log measures (pKa) due to many orders of magnitude spanned by Ka values.

Question 16

pKa equation

Answer 16

pKa= -log ( [H+] [A-] ) / [HA]

-log (product concentration) / weak acid reactants

pKa is a given constant

Tip: anything with a P= negative.

Question 17

What can act as buffers?

Answer 17

Weak acids and weak bases

Question 18

What do buffers do

Answer 18

They resist changes in pH when small quantities of acid or base are added to the solution.

Buffers can both bind or release proteins and, in doing so, prevent the pH from changing rapidly.

Question 19

How do weak acids react when strong bases are added

Answer 19

Strong bases (OH-) will bind to the hydrogen of the weak acid (HA) or conjugate acid produced by the weak base (HB) and produce water

This will create water and A- or water and

Question 20

How do weak bases react when strong acids are added

Answer 20

The weak base (B-) or conjugate base from a weak acid (A-) can neutralize any H+ (strong acid) added to the system to create HB or HA.

Question 21

When is a buffer at optimal strength

Answer 21

When there are equal amounts of HA and A- (weak acid and conjugate base). This occurs when pH= pKa

Question 22

What equation is useful for estimating the pH of a buffer solution

Answer 22

Henderson-hasselbalch

pH= pKa + log ([A-]/[HA])

Question 23

pH of blood

Answer 23

7.4

Question 24

Metabolic acidosis and metabolic alkalosis

Answer 24

Metabolic acidosis is 7.35 or below. Results in coma or death.
Metabolic alkalosis is 7.45 or above. Results in confusion and convulsions.

Question 25

4 categories of buffers

Answer 25

Proteins,phosphates, carbonic acid/bicarbonate, and respiratory and renal system also regulate acid-base balance.

Question 26

Where are protein buffers found

Answer 26

In blood plasma and cells. Nearly all proteins can function as buffers because the carboxyl functional group acts as a weak acid and the amino functional group acts as a weak base.

Question 27

Buffering by proteins accounts for ___ of the buffering power of the blood and ___ of the buffering within the cells

Answer 27

2/3

most

Question 28

Phosphate buffer weak acid and conjugate base

Answer 28

Weak acid- dihydrogen phosphate

Conj base- Monohydrogen phosphate

Question 29

Carbonic acid is the __ and bicarbonate is the ___

Answer 29

Weak acid, conjugate base

Question 30

Usually, ____ in the body function as buffers

Answer 30

Weak acids