C5(Chemical Changes) Flashcards
What is a strong acid ?
Strong acids fully ionise in aqueous solutions
What is an aqueous solution ?
It means dissolved in water .
Give three examples of a strong acid ?
Hydrochloric acid
Sulphuric acid
Nitric acid
What do acids produce in aqueous solutions ?
Hydrogen ions (H^+).
HCI (aq)—> H^+(aq) + Cl(aq).
When an adid molecule splits like this, we say the acid has ……….
Ionised !
What are the four state symbols ?
Aq(Aqueous)
l(liquid)
s(Solid)
g(gas)
In aqueous solutions, acid molecules ………
Ionise (split), and release H^+
What is HCI?
An acid molecule.
What is a weak acid ?
Weak acids partially ionise in aqueous solutions.
Which substance is oxidised in the reaction represented by this equation?
Lead oxide + carbon → lead + carbon dioxide
Carbon !
Which half equation represents the reaction that occurs at the anode in the extraction of aluminium by electrolysis?
2O2- → O2 + 4e-
Which substance is oxidised in the reaction represented by this ionic equation? - Higher
Zn + Cu2+ → Zn2+ + Cu
Zinc atoms lose electrons, so zinc is oxidised.
Name the products of the reaction between zinc and hydrochloric acid.
Zinc chloride + hydrogen gas
In the preparation of a salt, why is the saturated solution of the salt left in a warm, dry place for a few days rather than heated over a water bath?
To allow large crystals to form
What is the formula of the ion produced by acids in aqueous solution?
H+
In the preparation of zinc chloride crystals from zinc carbonate and hydrochloric acid, why is the mixture filtered after the zinc carbonate has been added to the acid?
To remove excess zinc carbonate
Which metal is found in the Earth as the metal itself?
Gold
Which substance is oxidised in the reaction represented by the ionic equation below?
Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)
Zinc because it loses electrons
What does a reversible reaction mean ?
Some acid molecules ionised but not all.
