sc8 Flashcards

1
Q

What colour is litmus in alkali and acidic solutions?

A

Acid -> red
Alkali -> blue

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2
Q

What colour is methyll orange in acid and alkali solutions?

A

Acid -> red
Alkali -> orange

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3
Q

What colour is phenolphthalein in acid and alkali solutions?

A

Acid -> colourless
Alkali -> pink

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4
Q

Metal + acid = ?

A

Salt + hydrogen

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5
Q

Metal oxide + acid = ?

A

Salt + water

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6
Q

Metal hydroxide + acid = ?

A

Salt + water

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7
Q

Metal carbonate + acid = ?

A

Salt + water + carbon dioxide

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8
Q

What is neutralisation?

A

A reaction between an acid and a base

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9
Q

What happens in an acid-alkali neutralisation reaction in terms of particles?

A

hydrogen ions (H+) from acid reacts with hydroxide ions (OH-) from the alkali to form water (H2O)

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10
Q

How do you carry out an acid-alkali titration?

A

1. use a pipette to add 25cm^3 of alkali to a clean conical flask

2. add few drops of indicator and put the conical flask on a white tile

3. fill burette with acid and note the starting volume

4. add acid from burette to conical flask slowly until indicator changes colour

5. note volume of acid in burette

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11
Q

Why is excess of the reactant added to prepare a soluble salt?

A
  • To ensure the volume of acid reacts completely
  • To make the solution formed pure
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12
Q

Why is the excess acid removed after?

A
  • done by filtration
  • so you are just left with salt and water
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13
Q

Why should titration be used when preparing a soluble salt?

A
  • so you can measure the exact amount of volumes that reacts
  • mix exact proportions of two reactants
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14
Q

What is the method of investigating the preparation of pure, dry hydrated copper Sulfate

A
  1. Add excess of copper oxide (insoluble) to sulfuric acid
  2. Use a filter and filter paper to filter off any copper oxide that hasn’t reacted
  3. blue solution formed
  4. Evaporate water by placing in a water bath
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15
Q

What salts are always soluble?

A
  • sodium salts
  • potassium salts
  • ammonium salts
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16
Q

All nitrates are soluble — true of false?

A

TRUE

17
Q

Which chlorides aren’t soluble?

A
  • silver
  • lead
18
Q

Which sulfates aren’t soluble?

A
  • lead
  • barium
  • calcium
19
Q

Are carbonates insoluble?

A

YES!

20
Q

How do you prepare a pure, dry sample of an insoluble salt?

A
  1. Mix two solutions needed for salt
  2. Filter mixture using filter paper which insoluble salt will be left on
  3. Wash salt using distilled water
  4. Leave salt to dry on filter paper
21
Q

Why should universal indicator not be used in titration experiments?

A

too many colours

22
Q

How can titration be improved?

A
  • use a white tile
    —> easier to see when indicator changes colour
  • rinse burette
    —> no impurities will affect result
23
Q

Why is litmus not a suitable indicator?

A
  • only shows if a solution is acidic or alkaline
  • doesn’t show how acidic it is
24
Q

what is the equation of hydrochloric acid?

A

HCL

25
Q

what is the equation for nitric acid?

A

HNO3

26
Q

what is the equation for sulphuric acid?

A

H2SO4

27
Q

what is the equation for calcium hydroxide?

A

Ca(OH)2

28
Q

why is the lab method for making crystals not suitable for large scale use?

A
  • large scale needs a lot of crystals
  • volumes of solution in large scale too large for titration
29
Q

why does reaction between metal + acid that forms salt stop even though there’s still some solid left?

A
  • salt is insoluble so forms a barrier
  • prevents further reaction of metal with acid
30
Q

what can be used to measure a solid base instead of a spatula?

A

scales

31
Q

what is shown when a reaction between metal + carbonate finishes?

A
  • no more fizzing
  • no further change in colour