PH MEASUREMENT AND BUFFER PREPARATION

Question 1

measure of how acidic/basic a solution is.

Answer 1

pH

Question 2

0 to 14.

Answer 2

range

Question 3

pH < 7

Answer 3

acidic

Question 4

pH = 7

Answer 4

neutral

Question 5

pH > 7

Answer 5

basic

Question 6

potential of hydrogen

Answer 6

ph

Question 7

measure of the hydrogen ion (H+) concentration in an aqueous solution

Answer 7

pH

Question 8

expressed as the negative logarithm of the hydrogen-ion concentration.
pH = - log [H+]

Answer 8

pH

Question 9

potential of Hydroxide

Answer 9

pOH

Question 10

measure of hydroxide ion (OH-) concentration

Answer 10

pOH

Question 11

expressed as the negative logarithm of the hydroxide-ion concentration.
pOH = - log [OH-]

Answer 11

pOH

Question 12

important in organism and their cells because chemical reactions and processes are affected by the hydrogen ion concentration.

Answer 12

control of pH

Question 13

requires a pH between 7.8 and 8.4

Answer 13

Nemo (Clownfish)

Question 14

compound that can donate a hydrogen ion.

Answer 14

acid

Question 15

substance that accepts hydrogen ions.

Answer 15

base

Question 16

Hydrogen ions
low ph/ many hydrogen ions

Answer 16

ACIDS

Question 17

(hydroxide ions)
high ph/ many hydroxide ions

Answer 17

ALKALIS

Question 18

Chemists have tried to define acids and bases in relation to their compositions and molecular structures.

Answer 18

Background

Question 19

defines acids as substances that produce H+ ions in aqueous solution while bases are substances that produce OH- ions in aqueous solution.
Pronounced as “svaan-tay”

Answer 19

Svante Arrhenius

Question 20

Mentioned that acids are electron-pair acceptors and bases are electron-pair donor.
However, the two mentioned definitions have limitations. Thus, the most useful and accepted definition of acids and bases nowadays are those proposed by Johannes Bronsted and Thomas Lowry, and it is known as the Bronsted-Lowry theory.

Answer 20

Gilbert N. (G.N.) Lewis

Question 21

• HCI (Hyrochloric acid) is an acid because it donates a proton making Cl- (Chloride) while water is a base because it accepts a proton making H30+.
• Furthermore, the theory explains that for every acid-base reaction, there is a creation of conjugate acid-base pair.
• In the above example Cl- is the conjugated base of HCl and H30+ is the conjugated acid of water as shown below.

Answer 21

Rationale:

Question 22

introduced the pH scale that measures the strength of an aqueous acidic or basic solution.
It converts the H+ concentrations to pH using the formula.
pH = - log [H+]

Answer 22

Seren Peter Lauritz Sorensen
(S.P.L.) Sorensen

Question 23

is “the negative common logarithm of the activity of hydrogen ion in solution

Answer 23

precise definition of pH

Question 24

The pH of a solution is the negative logarithm of the hydrogen-ion concentration.
pH = -log|H+]

Answer 24

Computation of pH & [H+]

Question 25

compute for the pH of pure water with [H+] = 1.0 × 10 -7 M (Molarity).

Answer 25

pH = -log|H + ] = - 10g|1.0 × 10 -7] = -(-7.00) pH = 7.00

Question 26

compute for the pH of pure water with [H+] = 1.0 × 10 -7 M (Molarity).

Answer 26

pH = -log|H + ] = - 10g|1.0 × 10 -7] = -(-7.00) pH = 7.00

Question 27

Compute for the pH of solution with [H+] = 2.3 × 10-5 M

Answer 27

pH = -log[H + ] = - 10g|2.3 × 10 -5] pH = 4.64 (Acidic)

Question 28

compute for the [H+] if pH is known using this formula:

Answer 28

[H+] = 10^-рН *Use the 10^x key on your calculator

Question 29

What is the [H+] of a solution with a pH of 9.14?

Answer 29

[Н+] = 10^-рН = 10^-9.14 [H+] = 7.24 × 101-10 M

Question 30

What is the [H+] of a solution with a pH of 5.4?

Answer 30

[H+] = 10^-pH =101-5.4 [H+] = 3.98 × 101-6 M

Question 31

The pOH of a solution is the negative logarithm of the hydroxide-ion concentration. рОН = -log[OH-] [ОН-] = 10^-рОН *Use the 10^x key on your calculator Constant: pH + pOH = 14

Answer 31

Computation of poH

Question 32

The pOH of a solution is the negative logarithm of the hydroxide-ion concentration. рОН = -log[OH-] [ОН-] = 10^-рОН *Use the 10^x key on your calculator Constant: pH + pOH = 14

Answer 32

Computation of poH

Question 33

A solution has a pH of 4. Find the pOH and [OH-].

Answer 33

pH + pOH = 14 рОН = 14 - рН рОН = 14 - 4 рОН = 10 [ОН-] = 10^-рОН = 10^-10 [OH-] =1 × 10^-10 M

Question 34

Find the pOH and [OH-] of a solution with a pH of 8.4.

Answer 34

pH + pOH = 14 рОН = 14 - рн рОН = 14 - 8.4 рОн = 5.6 [ОН-] = 10^-рОН = 10^-5.6 [OH-] = 2.5 × 10^-6 M

Question 35

If pH > 7 = Basic , <7 = Acidic If pOH >7 = Acidic , <7 = Basic 7 = Neutral

Answer 35

Interpretation of Results

Question 36

prevent changes in pH.

Answer 36

Buffers

Question 37

resist changes in the pH even when acids or bases are added.

Answer 37

Buffers

Question 38

are a mixture of a weak acid or alkali and one of its salts. Ex: acetic acid + sodium acetate

Answer 38

Buffers

Question 39

The ability of buffers to resist large changes in pH is governed by

Answer 39

Le Chatellier's principle.

Question 40

A principle of equilibrium shift due to changes in buffer conditions.

Answer 40

La Chatellier's Principle

Question 41

In our blood, carbonic acid is the most important buffer. This solution maintains our blood pH to facilitate transport of oxygen from the lungs to the cells.

Answer 41

Buffers in Human Blood

Question 42

normally slightly basic (7.35 to 7.45)

Answer 42

pH of blood

Question 43

simple test to check if a substance is acidic or basic using a litmus paper.

Answer 43

Litmus Test

Question 44

types of litmus paper available that can be used to identify acids and bases

Answer 44

red litmus paper and blue litmus paper

Question 45

turns red for acidic pH

Answer 45

Blue litmus paper

Question 46

turns blue for basic pH

Answer 46

Red litmus paper

Question 47

No color change

Answer 47

neutral pH

Question 48

impregnated with organic compounds that change their color at different pH values. The color shown by the paper is then compared with a color standard usually provided by the manufacturer.

Answer 48

Indicator Paper

Question 49

impregnated with organic compounds that change their color at different pH values. The color shown by the paper is then compared with a color standard usually provided by the manufacturer.

Answer 49

Indicator Paper

Question 50

should be calibrated first before being operating the device. The standard procedure for calibrating a pH meter is to calibrate it at three different pHs (pH 7, pH 4, and pH 10). After calibration, all that needs to be done is to insert the electrodes of the pH meter into the solution to be tested and read the pH flashed on the screen.

Answer 50

pH Meter

Question 51

an indicator that can be used to determine the pH value of a solution

Answer 51

pH PAPER

Question 52

an indicator that is used to determine the acidity or the basicity of a solution

Answer 52

LITMUS PAPER

Question 53

Can give the exact pH value of a solution

Answer 53

pH PAPER

Question 54

Cannot give the exact pH value of a solution

Answer 54

LITMUS PAPER

Question 55

Give more precise results

Answer 55

pH PAPER

Question 56

Give a less precise indication

Answer 56

LITMUS PAPER

Question 57

Can give a range of colors

Answer 57

pH PAPER

Question 58

Can give only two colors

Answer 58

LITMUS PAPER