Colours

Question 1

ammonium ions

Answer 1

add sodium hydroxide solution and warm gently - gas turns red litmus blue

Question 2

copper II ions

Answer 2

add sodium hydroxide solution - blue precipitate

Question 3

iron II ions

Answer 3

add sodium hydroxide solution - green precipitate

Question 4

iron III ions

Answer 4

add sodium hydroxide solution - orange/brown precipitate

Question 5

chloride ions

Answer 5

add nitric acid and silver nitrate. makes white precipitate

Question 6

bromide ions

Answer 6

add nitric acid and silver nitrate. makes cream precipitate

Question 7

iodide ions

Answer 7

add nitric acid and silver nitrate. makes yellow precipitate

Question 8

sulfate ions

Answer 8

add hydrochloric acid and barium chloride - makes white precipitate

Question 9

carbonate ions

Answer 9

add dilute hydrochloric acid - carbon dioxide produced turns the limewater cloudy

Question 10

ammonia gas

Answer 10

damp litmus turns blue

Question 11

Fe (OH)2 or iron(II) hydroxide, (test for iron (II) ions

Answer 11

dark green gelatinous solid that forms when iron(II) ions are reacted with hydroxide ions, like from sodium hydroxide (NaOH)

Question 12

Fe (OH)3 precipitate (test for ion (III) ions)

Answer 12

rust-brown, gelatinous solid when sodium hydroxide (NaOH) is added to a solution containing iron(III) ions

Question 13

Cu (OH)2 precipitate (test for copper (II) ions)

Answer 13

blue precipitate, identified as Cu(OH)2, is a characteristic reaction used to confirm the presence of copper(II) ions in a solution.

Question 14

copper carbonate

Answer 14

Copper carbonate is green

Question 15

copper oxide

Answer 15

Copper oxide (CuO) is typically black

Question 16

barium sulfate precipitate (test for sulfate ions)

Answer 16

To test for sulfate ions, a solution is acidified with dilute hydrochloric acid, followed by the addition of barium chloride solution. If sulfate ions are present, a white precipitate of barium sulfate (BaSO4) will form. This precipitate is insoluble and will not dissolve when hydrochloric acid is added

Question 17

calcium carbonate

Answer 17

a synthetic form of calcium carbonate produced by a chemical reaction. It’s made by reacting calcium hydroxide (Ca(OH)2) with carbon dioxide (CO2), resulting in a white, pure calcium carbonate with a controlled crystalline structure.

Question 18

NO2 gas

Answer 18

Nitrogen dioxide (NO2) is a reddish-brown gas, a major air pollutant, and a member of the nitrogen oxides (NOx) family.

Question 19

N2O4 gas

Answer 19

Dinitrogen tetroxide (N2O4) gas is colorless. However, it is often seen in equilibrium with nitrogen dioxide (NO2), which is a reddish-brown gas. Therefore, a mixture of N2O4 and NO2 will appear as a brownish gas.

Question 20

zinc

Answer 20

Zinc is a silvery-white metal with a distinct bluish-grey or greyish-white hue.

Question 21

UI in hydrochloric acid

Answer 21

hydrochloric acid (HCl) would turn the indicator red or a shade of red

Question 22

UI in ethanoic acid

Answer 22

turn the solution orange or yellow

Question 23

UI in neutral solution

Answer 23

universal indicator (UI) will appear green.

Question 24

UI in ammonia solution

Answer 24

blue

Question 25

UI in sodium hydroxide

Answer 25

the solution will initially turn purple

Question 26

litmas paper in alkali

Answer 26

In an alkaline solution, red litmus paper turns blue

Question 27

litmas paper in neutral

Answer 27

turns purple in neutral solutions.

Question 28

colour of UI paper when dipped into HCI dissolved in methylbenzene

Answer 28

When a universal indicator (UI) paper is dipped into a solution of HCl dissolved in methylbenzene, the paper will likely remain purple or green, indicating a neutral or weakly acidic solution.

Question 29

potassium dichromate (VI) before oxidation of alcohol

Answer 29

the acidified potassium dichromate(VI) solution appears orange

Question 30

potassium dichromate (VI) after oxidation of alcohol

Answer 30

upon reaction with the alcohol, it changes to green.

Question 31

gasoline

Answer 31

Gasoline is typically yellow in color. However, gasoline can also be clear, white, or slightly amber

Question 32

fuel oil

Answer 32

Fuel oil is typically a dark brown or black liquid due to its higher boiling point and larger, longer hydrocarbon molecules.

Question 33

bitumen

Answer 33

Bitumen is a black, viscous liquid, meaning it is thick and sticky. This is because it's a constituent of crude oil and contains long hydrocarbon molecules.

Question 34

fluorine gas

Answer 34

Fluorine (F₂) is a pale yellow, diatomic gas,

Question 35

chlorine gas

Answer 35

Chlorine gas, a yellow-green gas with a pungent odor, is a halogen found in Group 7 of the periodic table.

Question 36

silver chloride precipitate (test for chloride ions)

Answer 36

The silver chloride precipitate is white. This color is a characteristic indicator when testing for halide ions in chemistry.

Question 37

silver bromide precipitate (test for bromide ions)

Answer 37

The silver bromide precipitate formed when testing for bromide ions is a cream-colored precipitate.

Question 38

silver iodide precipitate (test for iodide ions)

Answer 38

The precipitate of silver iodide (AgI) formed when testing for iodide ions is yellow

Question 39

bromine in organic solvent

Answer 39

Bromine, when dissolved in an organic solvent like cyclohexane, appears as a red-brown or orange solution.

Question 40

iodine in organic solvent

Answer 40

Iodine in organic solvents typically appears purple.

Question 41

flame when magnesium burns

Answer 41

When magnesium burns, it produces a very bright, dazzling white flame.

Question 42

flame when sulphur burns

Answer 42

When sulfur burns, it produces a blue flame.

Question 43

flame colour during incomplete combustion

Answer 43

During incomplete combustion, the flame is typically yellow or orange.

Question 44

sulfur

Answer 44

Sulfur's primary color is bright yellow.

Question 45

copper/metal

Answer 45

Copper metal typically has a reddish-brown or reddish-orange color, often described as reddish-metallic.

Question 46

carbon

Answer 46

Carbon can appear in various colors depending on its form. In its elemental form, carbon can be black (like graphite) or clear (like diamond).

Question 47

methyl orange in acid

Answer 47

In an acidic solution, methyl orange will appear red.

Question 48

methyl orange in alkali

Answer 48

In an alkaline (basic) solution, methyl orange exhibits a yellow color.

Question 49

bromine liquid

Answer 49

Bromine is a dark reddish-brown liquid at room temperature.

Question 50

iodine solid

Answer 50

Solid iodine is a purple-black color.

Question 51

iodine vapour

Answer 51

Iodine vapor is a striking deep purple color.