Topic 3 - Chemical Changes Flashcards Preview

Chemistry > Topic 3 - Chemical Changes > Flashcards

Flashcards in Topic 3 - Chemical Changes Deck (22):
1

What are the 5 pH indicators?

Universal Indicator
Litmus Paper
Methyl Orange
Phenolphthalein
PH Probe

2

What is an acid?

a substance with a pH less than 7 and containing H+ ions

3

What is a base?

a substance that reacts with an acid to form salt and water

4

What is an alkali?

A substance with a pH bigger than 7 and containing OH- ions

5

What does the litmus paper look like when the solution is acidic, alkali and neutral?

Acidic = red
Neutral = purple
Alkali = blue

6

What does methyl orange look when solution is alkali,neutral and acidic ?

Acidic = red
Neutral = yellow
Alkali = yellow

7

What colour does phenolphalein turn to when in acidic and alkali solutions?

Acidic = colourless
Alkali = pink
Neutral = colourless

8

What does the reaction between an acid and a base called? And what is the equation ?

Neutralisation.
acid + base = salt + water

9

Example of a neutralisation equation ?

H+ + OH- = H2O

10

TRUE OR FALSE
all acids can ionise/dissociate in solution.

True

11

What is ionisation/ dissociation ?

Splitting up a substance to produce H+ and another ion .

12

Example of ionisation

HNO3 = H+ + NO3-

13

What is a STRONG ACID?

Acid that ionises almost completely in solution. They tend to have a very low pH.

14

What is a weak acid ? What is their usual pH?

Acid that doesn’t fully ionise, their pH is around 2-6.

15

Example of a strong acid.

Hydrochloric

Sulfuric

Nitric

16

Example of a weak acid.

Ethanoic

Citric

Carbonic

17

Name 2 differences between a strong and a weak acid.

When weak acid is ionised the process can be reversed, unlike strong acids.

Higher pH with weaker acids

Step ionises almost completely, weak only partially

18

What is the concentration of an acid?

Measure of how much acid there is per 1 dm3 of water. Basically how watered down your acid is.

The more acid molecules compared to the volume of solution there is the higher concentration of the acid is present

19

How can the pH be increased ?

By decreasing the concentration of H+ using a factor of 10.
To go down by 2pH the concentration needs to decrease by a factor of 100 (10x10)

20

How can the pH can decreased?

It can be decreased by increasing the H+ ion concentration by a factor of 10.

21

Salt is a what type of compound ?

An ionic compound.

22

What salts do the following acids produce?
Hydrochloric
Sulfuric
Nitric

Hydrochloric = chloride salts
Sulfuric = sulfate salts
Nitric = nitrate salts