Chapter 4: Acids And Redox (4.1-4.3)

Question 1

What is the difference between a strong and a weak acid?

Answer 1

A strong acid completely dissociates in solution and released all its hydrogen atoms into solution but a weak acid only partially dissociates and releases some of its H+ atoms into solution.

Question 2

What happens when you add a base and an acid?

Answer 2

The base neutralises the acid to form a salt and water.

Question 3

What happens in neutralisation in terms of ions?

Answer 3

The H+ ions from the acid are replaced by metal or ammonium ions from the base.

Question 4

What is the ionic equation of reacting an acid with an alkali? I’m

Answer 4

H+(aw) + OH-(aq) -> H2O (l)

Question 5

What does a metal carbonate neutralise an acid to form?

Answer 5

Salt, water and carbon dioxide

Question 6

How do you make a standard solution?

Answer 6

1) Weigh solid
2) Dissolve solid in distilled water below the mark
3) Transfer solution to volumetric flash (RINSE THE BEAKER WITH DISTILLED WATER)
4) Fill flask to graduation line with distilled water (AVOID PARALLAX ERROR)
5) INVERT VOLUMETRIC FLASK SEVERAL TIMES - mixes solution

Question 7

How many decimal places does a burette reading have?

Answer 7

It is measured to the nearest 0.05, so it has to be either a 0 or 5 and has to be measured to 2 decimal places.

Question 8

Describe the procedure of an acid base titration

Answer 8

1) Add 25cm[3] (pipette) of alkali to conical flask
2) Add acid to burette and measure reading
3) Add indicator to the conical flask
4) Run the acid into the alkali until the indicator changes colour
5) Record the final burette reading
6) Quick trial titration to get approximate titre
7) Repeated accurately, adding solution dropwise we end point approaches until two accurate titres are concordant.

Question 9

When is the oxidation number 0?

Answer 9

In a pure element

Question 10

How do you work out total charge of a combined atom?

Answer 10

Sum of the oxidation numbers

Question 11

How do you know the oxidation number of the ion of an element ?

Answer 11

It is the same as the ionic charge but the sign comes before the number

Question 12

What is the oxidation number of H in metal hydrides?

Answer 12

-1

Question 13

What is the oxidation number of O in peroxides?

Answer 13

-1

Question 14

What is the oxidation number of O when bonded to F?

Answer 14

+2

Question 15

What do the Roman numerals in compounds mean?

Answer 15

The oxidation number of the element you don’t know the oxidation number of.

Question 16

Describe oxidation and reduction in terms of oxygen

Answer 16

Oxidation is the addition of oxygen and reduction is removal of oxygen

Question 17

Describe oxidation and reduction in terms of electrons

Answer 17

Oxidation is losing, reduction is gaining (OIL RIG)

Question 18

Describe oxidation and reduction in terms of oxidation numbers

Answer 18

Reduction is a decreases in oxidation number but oxidation is an increase in oxidation number