Atmosphere and acids Flashcards
What is an indicator?
a substance that changes colour in acid, alkali, neutral
What colour is an acid in methyl orange?
red
What colour is an acid in phenolphthalein?
colourless
What colour is an acid in universal indicator?
red
What colour is an acid in blue litmas?
red
What colour is an acid in red litmus?
red
What colour is neutral in methyl orange?
yellow
What colour is neutral in phenolphthalein?
colourless
What colour is neutral in universal indicator?
green
What colour is neutral in blue litmas?
blue
What colour is neutral in red litmas?
red
What colour is alkali in methyl orange?
orange/yellow
What colour is alkali in phenolphthalein?
pink
What colour is alkali in universal indicator?
dark blue
What colour is alkali in blue litmas?
blue
What colour is alkali in red litmas?
blue
Universal indicator:
acid?
1-6
strong acid = 1-3
Universal indicator:
neutral?
7
Universal indicator:
alkaline?
8-16
strong alkaline = 12-16
Examples of weak acid, strong acid, neutral, weak alkaline, strong alkali?
strong acid = sulphuric, batteries
weak acid = fruit
neutral = water, blood
weak alkaline = soap
strong alkaline = bleach
What is the composition of air, no water vapour?
nitrogen = 78%
oxygen = 21%
argon = 0.9%
carbon dioxide = 0.04%
other gases = trace amounts
Copper + oxygen = copper oxide
what happens in syringe?
heat (brown) copper
(black) copper oxide formed (greater mass than copper)
volume of air decreases as oxygen is used up
Copper + oxygen = copper oxide
Why does the pile of copper oxide turn black?
has been oxidised
reacted with oxygen and produced copper (II) oxide
Copper + oxygen = copper oxide
Why should syringe be cooled before measuring volume?
gases expand when heated therefore letting it cool = more accurate result