levo

Qualitative Tests

Flame tests for metal cations

  • 3 things to know
  • Unit AS 1

Overview

How the nichrome wire is cleaned before a flame test, flame colour given by lithium ions and flame colour given by sodium ions.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

Why is nichrome wire used to carry out a flame test?

Key term

Why is concentrated hydrochloric acid used rather than water in a flame test?

Key term

Which part of the Bunsen flame is used for a flame test, and why?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Why is nichrome wire used to carry out a flame test?

    Model answer

    Nichrome has a high melting point and gives no flame colour of its own, so it does not interfere with the result.

  2. 2

    Describe how the nichrome wire is cleaned before a flame test.

    Model answer

    The wire is dipped in concentrated hydrochloric acid and held in a hot Bunsen flame, and this is repeated until the flame shows no colour.

  3. 3

    Why must the wire be cleaned before every test?

    Model answer

    Traces of an earlier sample would give their own colour and could mask or be mistaken for the colour of the sample being tested.

  4. 4

    Why is concentrated hydrochloric acid used rather than water in a flame test?

    Model answer

    The acid converts the metal compound into its chloride, which is more volatile and vaporises readily in the flame.

  5. 5

    Which part of the Bunsen flame is used for a flame test, and why?

    Model answer

    The edge of the hot blue non-luminous flame is used, because a yellow luminous flame would obscure the colour produced.

  6. 6

    Explain in terms of electrons why a metal ion gives a coloured flame.

    Model answer

    Heat energy promotes electrons to higher energy levels, and the light of a characteristic colour is emitted as those electrons fall back down.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Formulae, Equations and Amounts of Substance
Atomic Structure
Bonding
Intermolecular Forces and Structure

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

Yellow to .
brownbluegreen

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe reactants total 159.6 + 84.0 = 243.6.
BThe two moles of iron have a mass of 111.6.
CThe atom economy is 45.8%.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

There are 1000 cm³ in one dm³.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Qualitative Tests, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.