Acids and Redox

Question 1

What is an acid according to the Brønsted-Lowry theory?

Answer 1

An acid is a substance that donates a proton (H+) to another substance.

Question 2

What is a base according to the Brønsted-Lowry theory?

Answer 2

A base is a substance that accepts a proton (H+) from another substance.

Question 3

What is the pH range of acidic solutions?

Answer 3

The pH range of acidic solutions is less than 7.

Question 4

Fill in the blank: A solution with a pH of 7 is considered _____ .

Answer 4

neutral

Question 5

What is the difference between strong and weak acids?

Answer 5

Strong acids completely dissociate in water, while weak acids partially dissociate.

Question 6

Which of the following is a strong acid? (a) HCl (b) CH3COOH (c) H2CO3

Answer 6

a) HCl

Question 7

Define oxidation in terms of electron transfer.

Answer 7

Oxidation is the loss of electrons by a substance.

Question 8

Define reduction in terms of electron transfer.

Answer 8

Reduction is the gain of electrons by a substance.

Question 9

What color change indicates the presence of phenolphthalein in an acid-base titration?

Answer 9

It changes from colorless in acid to pink in base.

Question 10

True or False: The oxidation state of an element in its elemental form is always zero.

Answer 10

True

Question 11

What is the oxidation state of sulfur in H2SO4?

Answer 11

The oxidation state of sulfur in H2SO4 is +6.

Question 12

What is the role of water in acid-base reactions?

Answer 12

Water can act as a solvent and also participate as an acid or base.

Question 13

What type of reaction is represented by the equation: Zn + CuSO4 → ZnSO4 + Cu?

Answer 13

It is a single displacement reaction.

Question 14

What does the term ‘neutralization’ refer to?

Answer 14

Neutralization is the reaction between an acid and a base to produce salt and water.

Question 15

What is the significance of the equivalence point in a titration?

Answer 15

The equivalence point is when the amount of acid equals the amount of base in a neutralization reaction.

Question 16

Fill in the blank: The reaction between hydrochloric acid and sodium hydroxide produces _____ and _____ .

Answer 16

sodium chloride; water

Question 17

What is the balanced equation for the reaction of sulfuric acid with sodium hydroxide?

Answer 17

H2SO4 + 2NaOH → Na2SO4 + 2H2O

Question 18

True or False: Oxidation states can be fractional.

Answer 18

False

Question 19

What is the oxidation state of chlorine in NaClO3?

Answer 19

The oxidation state of chlorine in NaClO3 is +5.

Question 20

What is the method for making a standard solution?

Answer 20

• Weigh by difference the mass of the solid to 2 decimal places
• Place the solid into a beaker
• Add 100cm³ of distilled water to the beaker
• Stir the solution to dissolve the solid
• Transfer the solution to a 250cm³ volumetric flask
• Rise the equipment into the volumetric flask
• Make up to the mark using distilled water
• Put on the lid and invert the solution several times

Question 21

What is the method for carrying out a titration?

Answer 21

• Rinse all glassware with distilled water and the standard solution
• Measure 25cm³ of the standard solution with a pipette filler and put that into the conical flask
• Add 3-4 drops of indicator and place the conical flask onto a white tile
• Using a funnel, fill the burette with acid until the bottom of the meniscus is on the 0 line
• Complete a rough titration to find the end point
• Repeat the experiment, adding the acid drop by drop to reach the end point. Rinse the conical flask between titrations with distilled water.
• Record results in a table and then calculate the mean titre using concordant results