Week
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Emerging
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Foundation
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Core
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Beyond Core
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Accomplished
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Can list 2 everyday facts about hydrogen, about acids and bases
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Can describe some general chemical properties of hydrogen, acids and bases
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Can explain that hydrogen is an interesting element, water is an interesting compound, and how this leads to acids and bases
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Can differentiate between strong, weak, concentrated and dilute acids and bases
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Can provide examples of some non-obvious compounds that behave as acids and bases (i.e. not hydrogen and anion, not hydroxide or carbonate)
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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 H
2O & that pOH is looking at how many OH- ions dissociate from H
2O.
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:
Describe what occurs during a neutralisation reaction.
Give some examples of common acids and bases.
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.
