Chemical analysis Flashcards
What is a formulation?
.Useful mixtures with precise purposes
.Made by following a formula
.Each component is in a measured quantity and it contributes to the properties of the formulation so it meets the required function
Test for chlorine
Chlorine bleaches damp litmus paper white
Test for oxygen
Put a glowing splint inside a test tube containing oxygen then the oxygen will relight the glowing splint
Test for carbon dioxide
Bubbling carbon dioxide through an aqueous solution f calcium hydroxide (lime water) causes the solution to turn cloudy
Test for hydrogen
Hold a burning splint at the open end of the test tube, if a squeaky pop is heard then hydrogen is present in the tube (the pop is from the oxygen and hydrogen reacting quickly in the air to form water)
What are carbonates?
Substances that contain CO3^2- ions
Test for carbonate ions
.Use a dropping pipette and add a few drops of dilute acid to a test tube containing your mystery substance
.Connect the test tube to a test tube containing lime water, if carbonate ions were present then CO2 would have been released from reaction with the acid which will turn the lime water cloudy when it bubbles through
What is a sulfate ion?
SO4^2-
Test for sulfate ions
.Use a dropping pipette to add a couple of drops of dilute hydrochloric acid followed by a couple of drops of barium chloride solution to a test tube containing the mystery solution, if sulfate ions are present then a white precipitate of barium sulfate will form
Ba^2+ + SO4^2- –>
BaSO4
Why is hydrochloric acid added in the test for sulfate ions?
Get rid of any traces of carbonate ions as these would also produce a precipitate and confuse the results
Give 3 examples of halide ions
Cl-, Br-, I-
Test for halide ions
.Add a couple of drops of dilute nitric acid
.Add a couple of drops of silver nitrate solution
.A certain colored precipitate will form depending on the halide
Ag+(aq) + ‘HALIDE-‘(aq) –>
Ag’HALIDE’(s)
In the test for halide ions, what color precipitate does a chloride ion give
White, silver chloride
In the test for halide ions, what color precipitate does a bromide ion give
Cream, silver bromide
In the test for halide ions, what color precipitate does an iodide ion give
Yellow, silver iodide
In the flame test, what color flame do lithium ion produce?
Crimson
In the flame test, what color flame do sodium ion produce?
Yellow
In the flame test, what color flame do potassium ion produce?
Lilac
In the flame test, what color flame do calcium ion produce?
orange-red
In the flame test, what color flame do copper ion produce?
green
Describe the steps involved in carrying out a flame test
.Clean a nichrome or platinum wire loop by rubbing it with fine emery paper and then holding it in a blue flame from a bunsen burner
.The flame might change color for a bit, once it turns blue again the loop is clean
.Dip the loop into the sample you want to test and put it back into the flame
.Record the color of the flame
What happens if you flame test substances with a mixture of different metal ions?
The flame colors of some ions may mask or hide the other colors
Describe the metal hydroxide test for metals
.Add a few drops of sodium hydroxide solution to a solution of your mystery compound
.Note down the color of the precipitate formed
In the metal hydroxide test for metals, what color precipitate does Calcium form?
White
In the metal hydroxide test for metals, what color precipitate does Copper (II) form?
Blue
In the metal hydroxide test for metals, what color precipitate does Iron (II) form?
Green
In the metal hydroxide test for metals, what color precipitate does Iron (III) form?
Brown
In the metal hydroxide test for metals, what color precipitate does Aluminium form?
White at first, then dissolves in the excess NaOH to form a colorless solution
In the metal hydroxide test for metals, what color precipitate does magnesium form?
White
Ca^2+(aq) + 2OH- (aq) –>
Ca(OH)2 (s)
Al^3+(aq) + 3OH-(aq) –>
Al(OH)3 (s)
What can line spectra do?
Identify ions in a solution and calculate their concentrations
What does the intensity of the spectrum indicate?
The concentration
How do flame tests emit colored light?
.As ions heat up, their electrons become excited (move to higher energy levels)
.When the electrons drop down to their original energy levels they release energy as light
.The combination of wavelengths emitted depends on the charge and electron arrangement
What is instrumental analysis?
Tests that use machines
Advantages of instrumental analysis
.Very sensitive
.Very fast
.Very accurate
