exercise 10-flame test

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Exercise 8

Flame Test

When elements are exposed to the heat of a flame, electrons in that element can be

excited from their ground-state arrangement into higher energy levels. As these excited

electrons return to the vacated lower levels excess energy MUS be emitted. !f the energy

emitted is in the visible region of the electromagnetic radiation spectrum, then a color will be

imparted to the flame. "nly certain elements have electronic transitions that involvethe energy associated with visible light. #ut, $ust as the electron arrangement in an element

affects its chemistry, the allowed electron transitions impart uni%ue color to the flame.

#ecause the energy of allowed levels for electrons in each element are uni%ue, any color

imparted to a flame is distinctive and an element can be identified by its flame test.

PROCEDURE:A. #unsen #urner

"bserve your professor&s demonstration of the

correct method of lighting a #unsen burner.

#. 'lame ests

(. "btain a flame test wire, cor) and two spot

plates.

*. +lean the spot-plates but do " dry them. After rinsing the clean plates with deionied

water, simply sha)e off the excess water.

. /ut one of the spot plates on a piece of paper and label the paper at the positions of the

spot plate wells with 0i+l, a+l, 1+l, +a+l*, #a+l*, or Sr+l*. a)e the spot plate 2on the

labeled paper3 to the stoc) bottles and using the droppers that are in the bottles, place

*- drops of each chemical into its labeled well. DO NOT !" UP T#E DROPPER$% &$ 'OUU$E T#E( RETURN E&C# TO T#E CORRECT )OTT*E%

4. 'orm the end of the flame test wire into a SMA00 loop. !nsert the straight end of the wire

into a cor). he cor) will protect your fingers from heat when you place the wire into the

flame of the #unsen burner.

5. +lean the wire by dipping it in a shell vial

containing a +e, m0 2(64th full3 of 7-M 8+l and

then placing the wire loop $ust above the inner blue

cone of a burner9s flame. :epeat this process until

no coloration of the flame is observed. 2he wire

is clean when no color is imparted to the flame.3

C*E&N UP &N' &C!D $P!**$ -!T# $OD!U

)!C&R)ON&TE

; < ; : =!/ A 8" '0AM;-;S W!:; !" A 1"W ": U1"W S"0U!". 8; +A!"

W!00 #; >#A1;=? "" 8; W!:; A= ! W!00 #; !M/"SS!#0; " +0;A@

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7. =ip the clean wire into one of the )nown solutions. /lace the wire into a flame $ust above

the inner blue cone. "bserve and record the color imparted to the flame. Sometimes it is

easier to see the color when the wire is held $ust above the visible flame.

. Bou MUS clean the flame test wire 2see step 43 # ; '" : ; testing a different solution.

:epeat the flame test process for the other )nown solutions. Save your solutions on yourspot plate in case you want to rechec) your results when you are testing your un)nown

solutions.

C. #ring your second clean spot plate 2on a piece of paper3 to your professor who will

dispense your un)nowns into it. "n the paper, label each your un)nowns with the numbers

given to you by your professor. Record these identi+ication numbers on .our report

sheet.

D. Ma)e sure to clean your wire -E** between each test and do a flame test on each of your

un)nown solutions.

(E. =ispose of your excess 7-M 8+l by pouring it into a bea)er of water and then pour thatsolution down the sin) flushing with additional water. D!$C&RD your flame test wire and

return the cor) and spot plates.

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:;/": AM;

'0AM; ;SS

S;+!"

'lame ests for 1nown Solutions

!dentity of Solution 'lame +olor

!dentification of Un)nowns

Un)nown umber 'lame +olor!dentity of Un)nown

Solution