Chemical Changes Flashcards

1
Q

Reactivity series in order

A
potassium
sodium
lithium
calcium
magnesium
CARBON
zinc
iron
HYDROGEN
copper
silver
gold
platinum
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2
Q

metals + acids =

A

metal salts + hydrogen

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3
Q

alkalis + water =

A

metal hydroxide solution + hydrogen

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4
Q

why is it not safe to react lithium, sodium and potassium with dilute acid?

A

because they would react so vigorously

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5
Q

metal + oxygen =

A

metal oxide

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6
Q

How does potassium react in cold water?

A

potassium reacts very quickly and the hydrogen produced ignites instantly and the metal sets alight, sparking and burning under a lilac flame

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7
Q

How does sodium react in cold water?

A

fizzes rapidly and melts to form a ball that moves around on the water surface

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8
Q

How does lithium react in cold water?

A

fizzes steadily and floats becoming smaller until it eventually disappears

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9
Q

which metals do not react with dilute acids?

A

copper, gold, silver, platinum

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10
Q

which metals react with dilute acid but not cold water?

A

magnesium, aluminium, zinc, iron and lead

iron and lead react really slowly

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11
Q

How are metals extracted?

A
  • most metals are found as metal oxides or compounds that can easily be changed to metal oxides
  • Metals less reactive than carbon can be extracted from their oxides by reduction with carbon
  • Metals that are more reactive than carbon are extracted from their molten compounds by electrolysis
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12
Q

briefly explain oxidation and reduction in terms of electrons

A

oxidation is loss

reduction is gain

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13
Q

What happens when substances dissolve in water?

A

dissociate into individual ions

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14
Q

What do acids produce in aqueous solutions?

A

H + ions

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15
Q

What do alkalis produce in aqueous solutions

A

OH- ions

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16
Q

What can the pH of a solution be measured with?

A

universal indicator
litmus paper
pH probe

17
Q

what is a base?

A

a substance with a pH greater than 7

an alkali is A SOLUBLE base

18
Q

acid + base =
acid + metal hydoxide =

(these are the same result)

A

salt + water

this is neutralisation

19
Q

acid + metal oxides =

A

salt + water

20
Q

acids + metal carbonate =

A

salt + water + carbon dioxide

21
Q

metal carbonate, metal oxides, alkalis, metal hydroxides all neutralise acids. this makes them what?

22
Q

How are soluble salts made?

A

by reacting acids with insoluble bases

23
Q

What examples of insoluble bases

A

metals, metal oxides, hydroxides or carbonates.

24
Q

What are strong acids?

A

acids that ionise completely in water

all particles dissociate to release H+ ions

25
What are weak acids?
acids that do not fully ionise in a solution only a small proportion of acids particles dissociate to release H+ ions
26
What are examples of strong acids?
hydrochloric, nitric and sulfuric acids.
27
What is the pH of a solution a measure of?
the concentration of H+
28
What are examples of weak acids?
ethanoic, citric and carbonic acids.
29
When the pH of a solution decreases by one unit, the hydrogen ion concentration does what?
increases by a factor of 10
30
DONT MIX UP strong acids and concentrated solution what is the difference between these two?
acid strength (strong or weak) tells you what proportion of the acid molecules ionise in water concentration measures how much acid there is in a certain volume of water
31
what salt does hydrochloric acid produce? Nitric acid sulfuric acid
chlorides nitrates sulfates