Topic 3 - Chemical changes - acids and bases (3.1-3.14) Flashcards

1
Q

what is an acid

A

a substance that produces hydrogen ions when dissolved in water

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2
Q

what is an alkali

A

a substance that produces hydroxide ions when dissolved in water

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3
Q

what colour does phenolphthalein turn alkali

A

pink

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4
Q

what colour does phenolphthalein turn acids

A

colourless

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5
Q

what colour does litmus turn for acids

A

red

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6
Q

what colour does litmus turn for alkalis

A

blue

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7
Q

what colour does methyl orange turn in alkalis

A

yellow

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8
Q

what colour does methyl orange turn for acids

A

red

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9
Q

what colour is methyl orange in a neutral solution

A

yellow

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10
Q

As a hydrogen ion concentration increases by a factor of 10, what happens to the pH of the solution.

A

Decreases by 1

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11
Q

what is the difference between alkalis and bases

A

alkalis are soluble bases

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12
Q

what is formed when a base and an acid react

A

salt and water only

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13
Q

acid + metal =

A

salt + hydrogen

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14
Q

acid + metal oxide = ?

A

salt + water

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15
Q

acid + metal hydroxide = ?

A

salt + water

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16
Q

acid + carbonate = ?

A

salt + water + carbon dioxide

17
Q

measuring pH core practical

A

use a measuring cylinder to add a set volume of HCl
estimate and record the pH of the contents of the beaker
measure the mass of the Ca(OH)2 or CaO on a weighing powder
add the powdered base to the beaker
stir and record the pH of the mixture
repeat until a maximum pH of 14 occurs.

18
Q

how can you measure pH more accurately

A

use a pH probe instead of universal indicator paper as it gives you more accuracy and values to 2dp.

19
Q

How is hydrogen formed at the cathode

A

Hydrogen ions are attracted to the negatively charged cathode where they are reduced to form hydrogen atoms.