Lab 3: pH and Buffers

Question 1

Define pH

Answer 1

pH is a measure of the concentration of hydrogen ions (H+) in a solution

Question 2

Describe an acid and an acidic solution

Answer 2

An acid is a substance that donates hydrogen ions (H+) into a solution. Acidic solutions contain a high concentration of hydrogen ions (H+)

Question 3

Describe a base and basic solution

Answer 3

A base is a substance that binds to hydrogen ions (H+) causing hydroxide ions (OH-) ions to be released. A basic solution has few hydrogen ions (H+)

Question 4

Explain the relationship between hydrogen ion concentration and pH

Answer 4

pH measures hydrogen ion concentration
The lower the pH means high hydrogen ion (H+) concentration
The higher the pH means the lower the hydrogen ion (H+) concentration

Question 5

Explain the use of the pH scale

Answer 5

The pH scale is used to describe the acidity or alkalinity of a solution based on the relative concentration of H+.

Question 6

Explain the use of the pH indicator

Answer 6

A simple way of determining the approximate pH of a solution depending on color changes

Question 7

Describe the function of a buffer and explain why buffers are important to life.

Answer 7

The function of a buffer is to maintain a particular pH of a solution, even when small amounts of acid or base are added to the solution.

Buffers are used in our blood, in order for us to maintain homeostasis

Question 8

hydrogen ion

Answer 8

H+/ cation (positively charged ion)

Question 9

hydroxide ion

Answer 9

OH-/ anion (negatively charged ion)

Question 10

acid

Answer 10

A substance that donates hydrogen ions (H+) into a solution

Question 11

base

Answer 11

A substance that binds to hydrogen ions (H+) in a solution causing a release of hydroxide ions (OH-)

Question 12

alkaline

Answer 12

Basic solutions

Question 13

neutral

Answer 13

A solution with an equal concentration of H+ and OH-

Question 14

pH

Answer 14

A measure of the concentration of hydrogen ions (H+) in a solution

Question 15

pH scale

Answer 15

Used to describe the acidity or alkalinity of a solution based on the relative concentrations of H+

Question 16

pH indicator

Answer 16

A substance that changes color depending on the pH of the solution, in order to determine the pH of the solution.

Question 17

anthocyanins

Answer 17

a pH indicator due to a group of pigments found in red cabbage that turns it the color purple

Question 18

pH buffer

Answer 18

a substance that can maintain a particular pH when small amounts of an acid or a base are added

Question 19

What are the two components of a buffer?

Answer 19

1. A weak acid that releases H+

2. A weak base that binds to H+

Question 20

How does a buffer work if the solution becomes basic?

Answer 20

If the solution becomes basic, the buffer donates H+ ions in order to increase the H+ concentration.

Question 21

How does a buffer work if the solution becomes more acidic?

Answer 21

If the solution becomes more acids, the buffer will bind to H+ ions producing more OH- ion s in the solution. Thus decreasing the H+ concentration

Question 22

buffering capacity

Answer 22

The ability of a buffer to resist changes in pH with the addition of increasing amounts of acid or base

Question 23

pH range

Answer 23

A certain range that a buffer can successful work within

Question 24

pH scale range for acidic solutions

Answer 24

0 to 6

Question 25

pH scale range for basic solutions

Answer 25

8 to 14

Question 26

pH scale range for neutral solutions

Answer 26

7

Question 27

What is the range of the pH scale

Answer 27

0 to 14

Question 28

alkaline

Answer 28

a (basic) solution that contains a low concentration of H+ ions

Question 29

acidic

Answer 29

a solution that contains a high concentration of H+ ions

Question 30

basic

Answer 30

a solution that contains a low concentration of H+ ions

Question 31

titration curve

Answer 31

pH curve that is a graph that describes how pH changes during various acid-base titrations

Question 32

phenol red

Answer 32

a pH indicator