Edexcel GCSE Chemistry Topic 3 Chemical changes overview quiz quiz

Hydroxide ion $OH^-$

Oxide ion $O^{2-}$

Hydrogen ion $H^+$

Sodium ion $Na^+$

It is a very concentrated solution with very little water in it

It contains absolutely no water molecules within the solution

It only partly breaks up into ions when it is dissolved in water

All of its molecules release their hydrogen ions in solution

increases by a factor of 10

decreases by a factor of 10

doubles

stays the same

A salt and hydrogen gas only, with nothing else

Salt, water and carbon dioxide

A salt and water only, with no gas given off

A salt and oxygen gas given off as bubbles

Zinc chloride

Zinc nitrate

Zinc sulfate

Zinc carbonate

To speed up the crystallisation of the salt

To give the final solution a deeper colour

To lower the pH of the solution below 1

To make sure all the acid has reacted

By a titration to add the exact volume of acid, then crystallising

By adding the alkali in excess and then filtering off the leftover solid

By mixing two solutions so the salt forms as an insoluble precipitate

By passing an electric current through the solution in electrolysis

Negative ions lose electrons (oxidation)

Positive ions gain electrons (reduction)

Water is filtered

The electrode dissolves into gas

Bromine

Hydrogen

Lead

Oxygen

Sodium is less reactive than hydrogen, so the sodium simply stays dissolved as ions

There are no sodium ions present at all in the sodium chloride solution

Hydrogen is the only gas that is dissolved anywhere in the whole solution

Sodium is more reactive than hydrogen, so the less reactive hydrogen is discharged

$2Cl^- \rightarrow Cl_2 + 2e^-$

$Cl_2 + 2e^- \rightarrow 2Cl^-$

$2Cl^- + 2e^- \rightarrow Cl_2$

$Cl^- \rightarrow Cl + e^-$

Evaporate the whole mixture to dryness, leaving everything behind together

Filter, wash the residue with distilled water, then dry it

Crystallise the filtrate to obtain the salt as solid crystals

Electrolyse the mixture to deposit the salt at the electrode