C3 questions for brainscape Flashcards
Which dissolved ions make water hard?
magnesium and calcium
What is the key difference between permanent and temporary hard water?
Temporary hardness ca be removed by boiling.
How is limescale formed?
hydrogen carbonate ions decompose on heating to form solid (precipitate) carbonates
Give an advantage of living in a hard water area
Calcium in water is good for growing strong teeth and bones. Also reduces heart disease
How does adding sodium carbonate soften water?
The Mg and Ca ions form a precipitate (carbonate) which can be fitered off. The ions are thus removed
Why can’t water softened using ion exchange be given to babies?
The Mg and Ca are replaced by sodium ions. Too much sodium is bad for you.
Why is chlorine added to our drinking water?
To kill microbes
Which group 7 element, other than chlorine, is sometimes added to water?
Fluorine, for healthy teeth.
Which two physical processes are involved in distillation?
boiling and condensing
Is bond breaking an exo or endothermic process?
Endothermic - you put energy in to break bonds
Is bond making an exo or endothermic process?
Exothermic - energy is released when bonds are made
Flame test colour - lithium
lithium - crimson
Flame test colour - sodium
sodium - yellow
Flame test colour - potassium
potassium - lilac
Flame test colour - calcium
calcium - red
Flame test colour - barium
barium - green
Al3+ ions with OH- (hydroxide) ions?
White precipitate of Al(OH)3 which dissolves in excess hydroxide
Ca2+ and Mg 2+ ions with OH- (hydroxide) ions?
White precipitates of Mg(OH)2 and Ca(OH)2 form
Cu2+ ions with OH- (hydroxide) ions?
blue precipitate forms Cu(OH)2
Fe2+ ions with OH- (hydroxide) ions?
green precipitate forms Fe(OH)2
Fe3+ ionswith OH- (hydroxide) ions?
rusty brown precipitate forms Fe(OH)3
What are the products when a carbonate reacts with acid?
carbon dioxide, water and a salt.
What is the chemical test for carbon dioxide?
Bubble it through lime water - it goes milky / cloudy white as a precipitate forms
What is the chemical test for sulphate ions?
Add barium chloride solution - a white precipitate forms if a sulhate is present.
What is the chemical test for chloride ions?
Add silver nitrate + nitric acid - white precipitate forms
What is the chemical test for bromide ions?
Add silver nitrate + nitric acid - cream precipitate forms
What is the chemical test for siodide ions?
Add silver nitrate + nitric acid - yellow precipitate forms
The alkali metals’ is the name for which group in the periodic table?
Group 1
In the periodic table, are elements arranged in order of mass number or atomic number?
Atomic number
What 2 products are made when an alkali metal reacts with water?
A hydroxide (alkaline) and hydrogen gas.
Which is more reactive - lithium or potassium?
potassium
Describe the trend in reactivity in group 1
As you go down the group they get more reactive.
What is the charge on each halide ion?
1- (group 7 - they gain 1 electron to get a full shell of 8 or 18)
The halogens’ is the name for which group in the periodic table?
Group 7
Which is more likely to form a coloured compound - chromium or calcium?
Chromium - because it is a transition metal.
