Chemical analysis

Question 1

What is a formulation?

Answer 1

.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

Question 2

Test for chlorine

Answer 2

Chlorine bleaches damp litmus paper white

Question 3

Test for oxygen

Answer 3

Put a glowing splint inside a test tube containing oxygen then the oxygen will relight the glowing splint

Question 4

Test for carbon dioxide

Answer 4

Bubbling carbon dioxide through an aqueous solution f calcium hydroxide (lime water) causes the solution to turn cloudy

Question 5

Test for hydrogen

Answer 5

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)

Question 6

What are carbonates?

Answer 6

Substances that contain CO3^2- ions

Question 7

Test for carbonate ions

Answer 7

.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

Question 8

What is a sulfate ion?

Answer 8

SO4^2-

Question 9

Test for sulfate ions

Answer 9

.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

Question 10

Ba^2+ + SO4^2- –>

Answer 10

BaSO4

Question 11

Why is hydrochloric acid added in the test for sulfate ions?

Answer 11

Get rid of any traces of carbonate ions as these would also produce a precipitate and confuse the results

Question 12

Give 3 examples of halide ions

Answer 12

Cl-, Br-, I-

Question 13

Test for halide ions

Answer 13

.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

Question 14

Ag+(aq) + ‘HALIDE-‘(aq) –>

Answer 14

Ag’HALIDE’(s)

Question 15

In the test for halide ions, what color precipitate does a chloride ion give

Answer 15

White, silver chloride

Question 16

In the test for halide ions, what color precipitate does a bromide ion give

Answer 16

Cream, silver bromide

Question 17

In the test for halide ions, what color precipitate does an iodide ion give

Answer 17

Yellow, silver iodide

Question 18

In the flame test, what color flame do lithium ion produce?

Answer 18

Crimson

Question 19

In the flame test, what color flame do sodium ion produce?

Answer 19

Yellow

Question 20

In the flame test, what color flame do potassium ion produce?

Answer 20

Lilac

Question 21

In the flame test, what color flame do calcium ion produce?

Answer 21

orange-red

Question 22

In the flame test, what color flame do copper ion produce?

Answer 22

green

Question 23

Describe the steps involved in carrying out a flame test

Answer 23

.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

Question 24

What happens if you flame test substances with a mixture of different metal ions?

Answer 24

The flame colors of some ions may mask or hide the other colors

Question 25

Describe the metal hydroxide test for metals

Answer 25

.Add a few drops of sodium hydroxide solution to a solution of your mystery compound .Note down the color of the precipitate formed

Question 26

In the metal hydroxide test for metals, what color precipitate does Calcium form?

Answer 26

White

Question 27

In the metal hydroxide test for metals, what color precipitate does Copper (II) form?

Answer 27

Blue

Question 28

In the metal hydroxide test for metals, what color precipitate does Iron (II) form?

Answer 28

Green

Question 29

In the metal hydroxide test for metals, what color precipitate does Iron (III) form?

Answer 29

Brown

Question 30

In the metal hydroxide test for metals, what color precipitate does Aluminium form?

Answer 30

White at first, then dissolves in the excess NaOH to form a colorless solution

Question 31

In the metal hydroxide test for metals, what color precipitate does magnesium form?

Answer 31

White

Question 32

Ca^2+(aq) + 2OH- (aq) -->

Answer 32

Ca(OH)2 (s)

Question 33

Al^3+(aq) + 3OH-(aq) -->

Answer 33

Al(OH)3 (s)

Question 34

What can line spectra do?

Answer 34

Identify ions in a solution and calculate their concentrations

Question 35

What does the intensity of the spectrum indicate?

Answer 35

The concentration

Question 36

How do flame tests emit colored light?

Answer 36

.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

Question 37

What is instrumental analysis?

Answer 37

Tests that use machines

Question 38

Advantages of instrumental analysis

Answer 38

.Very sensitive .Very fast .Very accurate