Acids, Alkalis, And Salts (Y11) Flashcards Preview

IGCSE edexcel Chemistry > Acids, Alkalis, And Salts (Y11) > Flashcards

Flashcards in Acids, Alkalis, And Salts (Y11) Deck (18)
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1
Q

What colour is litmus in acid and alkali?

A

Red in acid

Blue in alkali

2
Q

What colour is phenolphthalein in acid and alkali?

A

Clear in acid

Pink in alkali

3
Q

What colour is methyl orange is acid and alkali?

A

Pink/red in acid

Yellow in alkali

4
Q

What are acids?

A
  • acids neutralises bases
  • they dissolve in water
  • they release H+ ions
5
Q

What do the number of H+ ions lost tell you about the acid?

A
  • strong acids disassociate their H+ ions fully
  • weak acids disassociate their H+ ions partially
  • pH measures the number of H+ ions lost
6
Q

What are alkalis?

A
  • dissolve in water

* release hydroxide(OH-) ions

7
Q

What are bases?

A

• don’t dissolve in water
• neutralise acids
E.g. Copper or iron oxide, zinc carbonate

8
Q

explain the add excess base method

A

Add excess base: (e.g. Making copper sulphate)

  1. Add excess base to the acid until no more dissolves (warm acid if necessary)
  2. Filter off excess base
  3. Obtain dry salt from the solution
9
Q

Explain the titration method

A

Titration: (e.g. Hydrochloride acid and sodium hydroxide)

  1. Measure out the alkali using a pipette, and pour into conical flask
  2. Add acid via a Burnett to alkali, slowly, occasionally mixing, until indicator is neutral
  3. Add the same volume of acid to the same amount of alkali WITHOUT indicator
  4. Obtain dry salt from solution
10
Q

Explain the precipitation method

A

Precipitation: (e.g. Making lead iodide)
1. Make two solutions each containing an ion of the salt you want to make (these must be soluble)
2. Mix the solutions
3. Filter off the precipitate- the insoluble salt
4. Wash the precipitate with distilled water to remove any other salt solutions
5. Dry on filter paper or warm gauze
Example: sodium iodide + lead nitrate ➯ lead iodide + sodium nitrate
Colourless solution + colourless solution ➯ yellow precipitate + colourless solution

11
Q

What salts are soluble?

A

All nitrates
All chlorides except silver and lead
All sulfates except barium lead and calcium
Potassium, sodium and ammonium carbonates

12
Q

What salts are insoluble?

A

Silver chloride, lead chloride
Barium sulphate, lead sulphate, calcium sulphate
All carbonates except potassium, sodium, and ammonium

13
Q

How do you know what method to use to make a salt?

A
1. Is the salt soluble?
No: precipitation
Yes:
2:Is the base soluble? (I.e. Is it a hydroxide)
No: add excess base
Yes: titration
14
Q

How des the add excess base method work?

A
  • mix acid and base
  • add excess base until it no more dissolves
  • filter
  • heat to get rid of some water
  • leave to crystallise
  • wash w distilled water to get rid of any remaining acid/alkali
15
Q

How does titration work?

A
  • measure out alkali using pipette and pour into conical flask
  • add acid via a burette slowly, mixing occasionally, until indicator turns neutral
  • repeat but w/o indicator
  • heat solution to get rid of most of water
  • filter to remove water
  • allow to crystallise
16
Q

How does precipitation work?

A
  • make two soluble solutions each containing an ion of the salt you want
  • mix
  • filter off the precipitate- the insoluble salt
  • wash w distilled water to get rid of any other salt solutions
  • dry on filter paper/warm gauze
17
Q

What is concentration?

A

Concentration (moldm-3) = moles / volume

18
Q

How do you work out concentration calculations?

A
  • balance eq
  • write in what we know and what we must find out
  • work out mols of known
  • use ole ratios to find mols of unknown
  • using vol of unknown find conc of unknown