2.h - Chemical tests Flashcards
test for ammonia gas
- add sodium hydroxide and gently warm = if ammonia present = stinky smell
- damp ( so ammonia gas can dissolve ) piece of red litmus paper = if ammonia present= paper turns blue
test for carbon dioxide
limewater
if CO2 present = turns limewater cloudy
what are methods of collection for carbon dioxide ( 2 method)
collected over water ( CO2 slightly soluble in water + denser than air ) = gas jar on beehive shelf in a trough of water ( pushes less dense air out of the top of the jar )
what is a cheap of producing carbon dioxide
calcium carbonate + hydrochloric acid = carbon dioxide + calcium chloride + water
(1st way) of collecting carbon dioxide
thermal decomposition copper carbonate (green powder)
copper carbonate = carbon dioxide + copper oxide
heat copper (II) carbonate and collect the gas ( CO2) given off in a test tube.
what do flame test identify
metal ions
how do you carry out a flame test
- clean platinum wire loop by dipping it into some dilute HCl (hydrochloric acid )
- then hold it in a flame
- once loop burns in flame without any colour dip it into sample you want to test
- the put loop ( with sample testing on it ) back in the clear blue part of the Bunsen burner flame
flame test - red flame =?
Lithium = Li+
flame test - yellow- orange flame =?
Sodium = Na+
flame test - lilac flame =?
Potassium = K+
flame test - brick red flame =?
Calcium = Ca 2+
flame test - blue-green flame =?
Copper= Cu 2+
what colour flame does Lithium, Li+ produce
red
what colour flame does Sodium, Na+ produce
yellow-orange
what colour flame does Potassium, K+ produce
lilac
