Chapter 4 - Acids And Redox

Question 1

When an acid reacts with a base, what following reactions take place? (Three possible reactions)

Answer 1

• acid + metal oxide -> salt + water
• acid + metal hydroxide -> salt + water
• acid + metal carbonate -> salt + water + carbon dioxide

Question 2

What are acids?

Answer 2

Acids are protons (H+) donors

Question 3

Complete the sentence….

Strong acids are …………. dissociated

Weak acids are ………….. dissociate

Answer 3

• completely

* partially

Question 4

What are titrations?

Answer 4

• techniques used for accurate measurements of volume of one solution exactly with another solution

Question 5

What are titrations used for?

Answer 5

• finding concentration of a solution
• identifying of unknown chemicals
• finding purity of substance

Question 6

Titrations - how do you prepare a standard solution?

Answer 6

• weigh the solid first
• dissolve water in a beaker with distilled water then pour into volumetric flask
• carefully add distilled water a drop at a time until the menisuc is lined up with the line
• invert the flask slowly to make sure it is mixed evenly

Question 7

Titration - how do you do one?

Answer 7

• measure volume of one solution to conical flask
• add another solution to burette
• add a few drops of indicator to comical flask
• run burette solution into conical flask making sure to swirl for equal reaction
• indicators changes colour means the end point
• record final reading
• repeat multiple times for accuracy

Question 8

What is the mean titre?

Answer 8

Only use the closest accurate titres. Add all together and divide it by how many are where added together.

Question 9

Calculate percentage purity?

Answer 9

Percentage purity = (mass of pure substance/mass of impure substance) x 100

Question 10

What does OILRIG stand for?

Answer 10

• Oxidation
• Is
• Lose (of electrons)

•Reduction
•Is
Gain (of electrons)

Question 11

What oxidation state number is an element?

Answer 11

Zero

Question 12

Types of bases

Answer 12

• metal oxides
• metal hydroxide
• metal carbonate
• ammonia

Question 13

What does a base do to an acid?

Answer 13

Neutralises the acid to form a salt

Question 14

What’s an alkali?

Answer 14

It’s a base which dissolved in water releasing hydroxide ions (OH^-) into the solution

Question 15

What is an oxidation number?

Answer 15

A measure of the number of electrons in an atom used to bind with atoms of another element. Found by a set of rules

Question 16

Is the sign places in front or behind the oxidation number?

Answer 16

In front

Question 17

Sum of the total oxidation number = ……..

Answer 17

Total Charge

Question 18

There is a set order of elements need to find the unknown oxidation number. What order?

Answer 18

O = -2
H = +1
F = -1
Na^+ = +1
Mg^2+ = +2
Cl^- = -1

Question 19

What does redox reaction contain?

Answer 19

Oxidation and reduction

Question 20

Complete the sentences:
Reduction is a ……… in oxidation number
Oxidation is a …….. in oxidation

Answer 20

• decrease

* increase