Teste de Chama do Potássio

Identificação do potássio pela sua chama lilás/violeta

Flame Tests Beginner (Middle School) 20 min ~$6,00

Objetivo

Observar a cor lilás/violeta da chama produzida pelos íons de potássio, e aprender a usar vidro azul de cobalto para distingui-la da contaminação por sódio.

Contexto

Potassium produces a pale lilac or violet flame when heated. The emission occurs at 766.5 nm and 769.9 nm (near-infrared/deep red doublet). Because the flame is quite faint and easily overwhelmed by sodium's intense yellow, cobalt blue glass is used as a filter to block sodium emission and reveal potassium's true color.

Avisos de segurança

  • Wear safety goggles at all times
  • Keep hair tied back near open flames
  • Handle HCl with care

EPI necessário

goggles lab_coat

Materiais

  • Potassium chloride (KCl) (1 g)
  • Hydrochloric acid (HCl) (10 mL)
    1M concentration
  • Cobalt blue glass (1 piece)
    For filtering sodium light

Equipamentos

Bunsen burner Nichrome wire loop Watch glass Forceps

Procedimento

1

Clean the nichrome wire thoroughly by dipping in HCl and heating.

2 min
2

Place potassium chloride on the watch glass and collect a sample on the clean wire.

1 min
3

Hold the sample in the Bunsen burner flame. Observe with the naked eye first.

2 min
4

Now observe the flame through cobalt blue glass to filter out any sodium contamination.

2 min
5

Record the difference in appearance with and without the cobalt blue glass filter.

2 min

Resultados esperados

Without the filter, you may see a faint lilac color possibly masked by yellow from sodium impurities. Through the cobalt blue glass, a clear violet/lilac flame should be visible as the glass absorbs the yellow sodium emission.

Limpeza

Clean the wire loop with HCl. Return cobalt blue glass to storage.

Detalhes

Categoria
Flame Tests
Dificuldade
Beginner (Middle School)
Duração
20 min
Custo estimado
$6,00
Passos
5
Materiais
3

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Frequently Asked Questions

What is the objective of Teste de Chama do Potássio?
Observar a cor lilás/violeta da chama produzida pelos íons de potássio, e aprender a usar vidro azul de cobalto para distingui-la da contaminação por sódio.
How difficult is Teste de Chama do Potássio?
This experiment is rated as Beginner (Middle School). It takes approximately 20 minutes to complete.
What safety precautions are needed for Teste de Chama do Potássio?
Key safety precautions include: Wear safety goggles at all times; Keep hair tied back near open flames; Handle HCl with care.
What materials are needed for Teste de Chama do Potássio?
The main materials required are: Potassium chloride (KCl), Hydrochloric acid (HCl), Cobalt blue glass.
What results should I expect from Teste de Chama do Potássio?
Without the filter, you may see a faint lilac color possibly masked by yellow from sodium impurities. Through the cobalt blue glass, a clear violet/lilac flame should be visible as the glass absorbs the yellow sodium emission.