Acids, bases and salts Flashcards
What is an acid?
a substance which has the ability to donate H+ ions
/ An H+ donor
How does an acid react with a metal?
Acid + Metal -> Salt + hydrogen
[ONLY IF the metal is more reactive than hydrogen]
OBSERVATIONS:
- effervescence of a colourless gas
- If a metal is reactive the reaction is too violent to be carried out safely
How does an acid react with a metal hydroxide?
Acid + Metal hydroxide -> salt + Water
How does an acid react with a metal oxide?
Acid + metal oxide -> Salt + water
How does an acid react with a metal carbonate?
Acid + Metal carbonate -> Salt + Water + Carbon dioxide
OBSERVATIONS:
-Effervescence of a colourless gas
What is meant by the term “strong acid”? Give an example
-An acid that undergoes full dissociation in water, forming its constituent ions
E.g, hydrochloric/ sulfuric/ nitric acid
What is meant by the term “weak acid”? Give an example
-An acid that only slightly dissociates into its constituent ions in solution
E.g, Carboxylic acids
Give 3 examples of non metal oxides producing an acid
REACT WITH WATER:
- SO2(g) + H2O(l) → H2SO3(aq)
- 2NO2(g) + H2O(l) → HNO3(aq) + HNO2(aq)
- CO2(g) + H2O(l) → H2CO3(aq)
What is pH?
A measure of H+ concentration in aqueous solution
-The higher the H+ conc, the lower the pH/ more acidic the solution
What is the relationship between the vales for pH and conc of H+
A change of 1 on the pH scale corresponds to a change by a factor of 10 in H+(aq) ion concentration
What is meant by the term “monoprotic acid”? Give an example
-They are only able to donate 1 acidic H+ (aq) ion per acid molecule
E.g, HCl, HNO3, CH3COOH
What is meant by the term “diprotic” acid
- They are able to donate 2 acidic H+ ions per molecule;
- donate more than 1 mole of H+ ions
E.g, H2SO4
What is meant by the term triprotic acid?
- They are able to donate 3 acidic H+ ions per molecule;
- donate more than 1 mole of H+ ions
E.g, H3PO4
What is a base?
- a substance that can accept H+ ions
- able to form OH−(aq) in solution
What is meant by the term “strong base”? Give an example
A base (alkali) which undergoes full dissociation in water, forming its constituent ions
E.g, NaOH, KOH
What is meant by the term “weak base”? Give an example
A weak base that only partially forms ions in solution
E.g, Ammonia (NH3)
How do metal hydroxides react with water to form alkaline solutions?
1) NaOH(s) + H2O(l) → Na+(aq) + OH−(aq)
2) Ca(OH)2(s) + H2O(l) ⇌ Ca2+(aq) + 2OH−(aq)
How do metal oxides react with water to form alkaline solutions?
1) Na2O(s) + H2O(l) → 2Na+(aq) + 2OH−(aq)
2) BaO(s) + H2O(l) → Ba2+(aq) + 2OH−(aq)
What type of reaction occurs when an acid reacts with a base?
NEUTRALISATION
Describe the way in which an acid and base react
-Neutralisation reaction takes place
-It is a process of bond forming:
H+(aq) + OH−(aq) → H2O(l)
-Bond forming releases energy
-Is often an EXOthermic reaction
