ST.8 Acids and Bases N5 (CCS) Flashcards
What are alkalis?
Soluble bases
When are alkaline solutions formed?
When metal oxides are dissolved in water
When are acidic solutions formed?
When non-metal oxides are dissolved in water
Are bases soluble in water?
No
Why are acid and alkaline solutions able to conduct electricity?
They have free ions ables to carry the charge
Name 2 strong acids
Hydrochloric acid and sulfuric acid
What is meant by a “strong acid”?
They can fully dissociate into their component ions
What is meant by a “weak acid”?
Weak acids can only partially dissociate into their component ions
What happens when an acid is diluted?
The concentration of H+ ions decreases and the pH moves towards 7
Give 3 examples of weak acids
Ethanoic acid, citric acid and carbonic acid
What happens when an alkali is diluted?
The concentration of OH- decreases and the pH moves towards 7
What determines how well an acid or alkali conducts?
How concentrated the acid or alkali is
What does water break down into?
H+ and OH- ions
What does ⇌ mean?
That a dissociation is reversible
What does dissociation mean?
The process in which molecules separate or split into other things such as atoms, ions, or radicals
What is equilibrium?
A small proportion of water breaking down into H+ and OH- ions and then reacting again to produce water. It is present in water and all aqueous solutions
What ratio of ions are in acids, alkalis and neutral solutions?
Acid - H+ > OH-
Alkali - H+ < OH-
Neutral H+ = OH-
What experiment changed a pH by 1?
1 in 10 dilution
Give examples of some bases
Metal oxides, metal hydroxides, metal carbonates and ammonia
What is a neutralisation reaction?
When a base reacts with an acid to form a salt and water
List 3 neutralisation equations
Metal oxide + acid —-> salt + water
Metal hydroxide + acid —-> salt + water
Metal carbonate + acid —-> salt + water + carbon dioxide
Give acid names with salt endings
Hydrochloric - chloride
Sulfuric - sulfide
Nitric - nitride
Explain why water is always formed in neutralisation reactions
The H+ ion from the acid joins the OH- ion from the alkali
(H+ + OH- —-> H2O)
What is a spectator ion?
Ions that are present in the reaction but are unchanged by the reaction so must be the same state from start to end
i.e H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) —> Na+(aq) + Cl-(aq) + H2O (l)
becomes…
H+(aq) + OH-(aq) —-> H2O (l)
What can neutralisation reactions be used for?
To prepare soluble salts
What can also be used to prepare soluble salts?
Titrations
How can a titration prepare a soluble salt?
Once the volumes of acid and alkali have been recorded, the reaction can be repeated without the indicator to produce an uncontaminated salt solution. The solution can then be evaporated to dryness
How can insoluble metal carbonates and insoluble metal oxides be used to produce soluble salts?
Excess base is added to the appropriate acid, the mixture is filtered and the filtrate is evaporated to dryness
