GCE Acceptable Colour Changes and Observations Flashcards
What colour is fluorine gas?
Yellow
What colour is chlorine gas?
Green
What colour is bromine liquid?
Red-brown
What colour is bromine gas?
Red-brown vapour
What colour is iodine solid?
Grey-black
What colour is iodine vapour?
Violet / purple
What colour is chlorine water?
Green / colourless
What colour is bromine water?
Yellow / orange / brown
What colour is iodine solution in a polar solvent?
Yellow / brown
What colour is iodine solution in a non-polar solvent?
Violet / purple
Give an example of a non-aqueous solvent
Hexane
What are the observations when solid fluoride is reacted with concentrated sulfuric acid?
Steamy / misty fumes (of HF) produced
What are the observations when solid chloride is reacted with concentrated sulfuric acid?
Steamy / misty fumes (of HCl) produced
What are the observations when solid bromide is reacted with concentrated sulfuric acid?
Steamy / misty fumes (of HBr) produced
Red-brown vapour (Br2) produced
What are the observations when solid iodide is reacted with concentrated sulfuric acid?
Steamy / misty fumes (of HI) Violet / purple vapour (I2) Smell of rotten eggs (H2S) Yellow solid (S) Grey-black solid (on the sides of the test-tube) (I2)
What are the observations when solid fluoride is reacted with concentrated phosphoric acid?
Steamy / misty fumes (of HF)
What are the observations when solid chloride is reacted with concentrated phosphoric acid?
Steamy / misty fumes (of HCl)
What are the observations when solid bromide is reacted with concentrated phosphoric acid?
Steamy / misty fumes (of HBr)
What are the observations when solid iodide is reacted with concentrated phosphoric acid?
Steamy / misty fumes (of HI)
What colour is phenolphthalein in acidic solutions?
Colourless
What are the two main indicators for acid-base titrations?
Phenolphthalein and methyl orange
What colour is phenolphthalein in neutral solutions?
Colourless
What colour is phenolphthalein in alkaline solutions?
Pink
What colour is methyl orange indicator in acidic, neutral and alkaline solutions?
Acidic = red Neutral = orange Alkaline = yellow
What indicator is suitable for titrations with a strong acid-strong base or a weak acid-strong base?
Phenolphthalein
What indicator is suitable for titrations with a strong acid-strong base or a strong acid-weak base?
Methyl orange
What is the colour change at endpoint of methyl orange when adding acid to alkali?
Yellow to red
Alkali in conical flask, acid in burette
What is the colour change at endpoint of methyl orange when adding alkali to acid?
Red to yellow
Acid in conical flask, alkali in burette
What is the colour change at endpoint of phenolphthalein when adding alkali to acid?
Colourless to pink
Acid in conical flask, alkali in burette
What is the colour change at endpoint of phenolphthalein when adding acid to alkali?
Pink to colourless
Alkali in conical flask, acid in burette
What is the test for hydrogen gas?
Gives a ‘pop’ with a burning splint
What is the test for carbon dioxide gas?
Bubble through limewater, limewater turns milky
What is the test for chlorine gas?
Turns damp blue litmus paper red (due to HCl and HClO), then bleaches it (due to HClO)
What is the test for oxygen gas?
Relights a glowing splint.
What is the test for HCl?
Dip a glass rod in conc. ammonia. In the presence of hydrogen chloride gas, dense white fumes (NH4Cl, ammonium chloride) will be produced.
What is the test for NH3?
Dip a glass rod in conc. HCl. In the presence of ammonia gas, dense white fumes (NH4Cl, ammonium chloride) will be produced.
What colour will lithium ions appear in a flame test?
Crimson
What colour will sodium ions appear in a flame test?
Yellow / orange
What colour will potassium ions appear in a flame test?
Lilac
Pink through cobalt glass
What colour will calcium ions appear in a flame test?
Brick red
What colour will barium ions appear in a flame test?
Apple green
What colour will copper ions appear in a flame test?
Blue-green
What is the test for ammonium ions?
Warm with a solution of sodium hydroxide. A pungent smell will be observed.
What is the test for sulfate ions?
SO4 2-
Make a solution and add a solution of barium chloride or barium nitrate - forms a white precipitate.
What is the test for halide ions?
Make a solution in dilute nitric acid and add silver nitrate solution, then note the following:
Cl- ion = white precipitate, soluble in dilute ammonia solution.
Br- ion = cream precipitate, soluble in concentrated ammonia solution.
I- ion = yellow precipitate, insoluble in concentrated ammonia solution.
What is the test for carbonate ions?
Add dilute acid to from colourless gas which turns limewater milky.
What is the test for iodine?
Add a few drops of starch to the solution, the solution will turn blue-black.
What are the observations when a hydrocarbon is burnt?
A smoky/sooty flame is indicative of a high carbon content and for incomplete combustion.
What is the test for alkenes?
Test for unsaturation
Add a few cm^3 of bromine water. After shaking the aqueous layer will decolourise.
What are the observations when an alcohol is burnt?
A non-smoky/non-sooty/clean blue flame is indicative of complete combustion/low carbon content.
A sooty/smoky flame is indicative of incomplete combustion/high carbon content.
What are the observations when an alcohol is reacted with sodium?
Solid disappears, fizzing, mixture warms up.
What are the observations when an alcohol is reacted with phosphorus pentachloride?
Solid disappears, steamy/misty fumes, mixture warms up, hissing noise.
What are the observations when an alcohol is oxidised?
Primary and secondary alcohols with acidified potassium/sodium dichromate (VI) solution changes from orange to green when heated, change in smell.
What are the observations when magnesium is reacted with water?
Few bubbles produced slowly, metal dulls
What are the observations when calcium is reacted with water?
Fizzing, mixture warms up, metal rises and falls, metal disappears, white solid produced.
What are the observations when magnesium/calcium is reacted with hydrochloric acid?
Metal disappears, fizzing, mixture warms up
What are the observations when magnesium is reacted with sulfuric acid?
Metal disappears, fizzing, mixture warms up
What are the observations when calcium is reacted with sulfuric acid?
Fizzing initially but reaction stops (due to formation of insoluble calcium sulfate)
What are the observations when magnesium is burnt in oxygen?
Bright white light to form a white powder.
What are the observations when calcium is burnt in oxygen?
Brick red flame to form a white powder