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Chemistry Yr 11 > Flame tests > Flashcards

Flashcards in Flame tests Deck (9)
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1

Why is analysis important

to check composition of substances eg quality control manufacturing and detect polution

2

Define flame test

analytical technique using fact that when heated atoms of different metals emit different frequencies of light a and are seen as different colours

3

What is a flame test an eg of?

emission spectroscopy

4

Colours in flame test for cations.

Barium (Ba2+) - apple green flame
Calcium (Ca2+) - orange/red flame
Copper (Cu+ and Cu2+) - Blue green flame
Potassium (K+) - Lilac
Sodium (Na+) - Orange

5

Cause of coloured light?

Electrons orbit nucleus in a distant energy levels.
if energy supplied to atom , some electrons may absorb a quantum of extra energy and jump to a higher (outer) energy level.
These electrons are in excited state.
Eventually excited electron falls back to original position.- ground state- giving out extra energy as drops.
Extra energy emitted as visible light.
Amount of energy determines wave length and colour of light.

6

Each element has own

Unique electron configuration.
Characteristic pattern of wavelengths absorbed and emitted.
Called element's spectrum

7

Element's spectrum can identify what

Element.
To measure how much element is present in sample being tested.

8

What component of salts is responsible for colours observed?

Metals

9

Why must clean watch glass be used for each test?

If salt left from previous test, may mix with intended salt to use next causing inaccurate results.