Acids and Bases Flashcards
state the properties of acids
- Sour taste
- turns blue litmus paper red
- pH under 7
- aqueous solution can conduct electricity
state the properties of alkalis
- bitter taste, soapy feel
- turns red litmus paper blue
- pH over 7
- aqueous solution can conduct electricity
Define strong acids
A strong acid is one where the acid molecule is completely ionised in water, forming more H +ions and result in a higher concentration of H +ions
Define weak acids
A weak acid is one where the acid molecule is partially ionised in water, forming fewer H +ions and result in a lower concentration of H +ions. Most of the acid molecules remain as undissociated acid molecules.
Why is hydrochloric acid monobasic?
For every concentration of HCl, the same concentration of H +ions are produced. Hence, 1 mole of HCl produces 1 mole of H +ions.
Why is sulfuric acid dibasic?
For every concentration of sulfuric acid, the double concentration of H +ions are produced. Hence, 1 mole of sulfuric acid produces 2 moles of H +ions.
Why is ethanoic acid a weak acid?
For every concentration of ethanoic acid, less concentration of H +ions are produced than the original concentration of acid, indicating that this is a weaker acid,
Why is controlling pH of soil important?
- Plants grow best in neutral / slightly alkaline soil
- But the pH of soil may become too acidic due to acid rain or too much fertiliser added;
How do we control acidity of soil?
- Adding calcium hydroxide
- slaked lime (alkaline solution) to soil is to help reduce acidity of soil.
- The hydroxide ions in calcium hydroxide neutralises the hydrogen ions in the acidic soil, thus increasing the pH of the soil. [change to pH] - H (+) (aq) + OH (–) (aq) → H2O(l)
How to select the correct indicator for titration?
A good choice of indicator is one in which the change over point for indicator coincides with the endpoint of titration.
