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Flashcards in 5 - acids Deck (28):
1

Define acid

An acid is a proton donor

2

How do we know if a substance is an acid if we have the chemical formula?

It contains H+ ions

3

What happens when you put an acid in water?

It releases H+ ions and the other negative ion

4

What are the chemical formulae of the 4 main acids?

Hydrochloric = HCl

Sulphuric = H~2 SO~4

Nitric = HNO~3

Ethanoic = CH~3 COOH

5

What does dissociate mean?

When an acid is put into water and the ions are released into the water

6

What makes an acid strong or weak?

A strong acid completely dissociates

A weak acid partially dissociates

7

What is a H+ ion physically?

Just a proton

8

Define base

A proton accepter

9

What are the main examples of bases?

Hydroxides, oxides, ammonia etc.

10

Define alkali

A type of base which dissolves in water to release OH- ions

basically, a hydroxide

11

What is the only common alkaline gas?

Ammonia

12

What happens when ammonia is put in water?

Ammonium ions and hydroxide ions are released

13

Define salt

A substance which is formed when a H+ ion from an acid is replaced by another positive ion (could be metal ion)

14

What happens when a salt and base react?

Salt and water are formed

15

What are the salts formed by the 4 main acids?

Hydrochloric --> chloride

Sulphuric --> sulphate

Nitric --> nitrate

Ethanoic --> ethanoate

16

What is the state of matter of acids, bases and salts?

acids are aqueous

salts are usually aqueous unless specified otherwise

Bases are either aqueous or solids

17

How do the 4 main acids dissociate?

H~2 SO~4 --> 2H+ + SO~4 2-

HCl --> H+ + Cl-

HNO~3 --> H+ + NO~3-

CH~3 COOH --> H+ + CH~3 COO-

18

What is the ionic equation for all reactions between acids and alkalis?

H+ + OH- --> H~2 O

19

What is the ionic equation between acids and bases?

Find the salt and deduce which 2 ions it's made from

You write that those 2 ions go to the salt

That is the ionic equation

20

What happens when a acid reacts with a metal?

Acid + metal --> salt + hydrogen gas

21

When happens when an acid reacts with a carbonate?

Acid + carbonate --> salt + carbon dioxide + water

22

What happens when an acid reacts with ammonia?

Ammonia + acid --> ammonium salt (and nothing else)

23

What happens when an acid reacts with any other base?

Acid + base --> salt + water

24

Describe how to prepare a standard solution

Weigh the solid accurately

Dissolve the solid in a beaker but don't fill it

Transfer the solution to a volumetric flask and rinse traces of solution from the beaker to the flask

Carefully fill the volumetric flask to the graduation line (read the meniscus at eye level)

Invert the flask several times to ensure the solution is well mixed

25

Describe the method of titration

Using a pipette, we measure a volume of the standard solution into a conical flask

The other solution is placed in a burette and the volume is recorded

A few drops of indicator is added to the solution in the conical flask

The solution in the burette is added to the conical flask until the reaction has just completed (this is the equivalence point) and we see a different colour

The volume of solution added from the burette is calculated (this is called the titre)

The experiment is repeated until 2 titres are concordant to 0.1 cm^3

The mean titre is calculated to 1 decimal place and only concordant titres are used in the mean

26

Explain the effect on the titre of filling the flask above the graduation line

This would cause the standard solution to be less concentrated

This means the titre volume would be larger in order to neutralise the standard solution

27

Explain the effect on the titre of not inverting the flask

The concentration would now be inaccurate because it wouldn't be the same throughout the standard solution

This causes the titre to be simply inaccurate

28

Explain the effect of the burette readings being taken from the top of the meniscus

Looking at the readings from above will give less accuracy in the readings because it is harder to differentiate between the different reading marks

This would cause the calculated titre to be less accurate than if the readings were taken at eye level