Week 6: Acids & Bases

Week	Emerging	Foundation	Core	Beyond Core	Accomplished
	Can list 2 everyday facts about hydrogen, about acids and bases	Can describe some general chemical properties of hydrogen, acids and bases	Can explain that hydrogen is an interesting element, water is an interesting compound, and how this leads to acids and bases	Can differentiate between strong, weak, concentrated and dilute acids and bases	Can provide examples of some non-obvious compounds that behave as acids and bases (i.e. not hydrogen and anion, not hydroxide or carbonate)

pH - the "Power of Hydrogen" - how many H+ ions have dissociated compared to OH- ions.

The logarithmic scale of pH means that as pH increases, the H+ concentration will decrease by a power of 10. Thus at a pH of 0, H+ has a concentration of 1 M. At a pH of 7, this decreases to 0.0000001 M. At a pH of 14, there is only 0.00000000000001 M H+.

Additional Resources:

My favourite: Visually explain Weak/Strong & Dilute/Concentrated

Concentrated or Dilute & Strong or Weak

Text: How do chemists work out a pH??



The following diagram can be used to understand that pH is looking at how many H+ ions have dissociated (split) from H2O & that pOH is looking at how many OH- ions dissociate from H2O.

The smaller the 'p' number, the smaller the number of ions that have not dissociated....

ie there are HEAPS AND HEAPS of H+ ions in a pH of a small number - and there are HARDLY ANY dissociated H+ ions in a pH of a large number.

Conversely, in a small pOH number, the of OH- ions is HEAPS AND HEAPS &
in a large pOH number, there are HARDLY ANY dissociate OH- ions.


See this next image - it tells you that a pH of 0 means that only 1 H2O molecule hasn't dissociated.

Accomplished clue: there is a word that chemists use that describes a compound or ion that can act as both an acid or a base....find it out first, and then it will help your research!!! Good luck!




Next week: Neutralisation

Here are a few resources to begin understanding our concept for week 5:

BBC Bitesize Neutralisation
Animation of Neutralisation

Before the next lesson, give these a go:

1. Describe what occurs during a neutralisation reaction.
2. Give some examples of common acids and bases.
3. Name the salt produced and write balanced equations for the reaction when the following substances are mixed:
   • hydrochloric acid and potassium hydroxide
   • sulfuric acid and barium hydroxide
   • nitric acid and sodium hydroxide
   • hydrochloric acid and calcium hydroxide.