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The pH Scale The Power or Potential of Hydrogen Topic 8.4
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Logarithm and pH scientists don’t like really big or really small numbers – use scientific notation the pH scale was proposed to simplify the comparison of concentrations of H + ions in solution the pH scale is based on the log 10 scale – the base 10 logarithm scale is simply an exponential scale (scientific notation) written in a different form
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Properties of Water water is neutral – it has equal concentrations of both [H 3 O + ] = [OH - ] [H 3 O + ] = 1x10 -7 [OH - ] = 1x10 -7
![Properties of Water water is neutral – it has equal concentrations of both [H 3 O + ] = [OH - ] [H 3 O + ] = 1x10 -7 [OH - ] = 1x10 -7](http://images.slideplayer.com/25/7819040/slides/slide_4.jpg "Properties of Water water is neutral – it has equal concentrations of both [H 3 O + ] = [OH - ] [H 3 O + ] = 1x10 -7 [OH - ] = 1x10 -7")
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Hydrogen ions from water water will self-ionize to a very small extent in pure water at 25°C, the [concentration] of H + ions/H 3 O + and OH - ions are equal – [H 3 O + ] = [OH - ] – both have a concentration of 1.0 x 10 -7 M acid solutions have a greater concentration of H + ions/H 3 O + than OH - ions basic solutions are opposite and have more OH -, and also referred to as alkaline solutions http://phet.colorado.edu/en/simulation/acid- base-solutions
![Hydrogen ions from water water will self-ionize to a very small extent in pure water at 25°C, the [concentration] of H + ions/H 3 O + and OH - ions are equal – [H 3 O + ] = [OH - ] – both have a concentration of 1.0 x M acid solutions have a greater concentration of H + ions/H 3 O + than OH - ions basic solutions are opposite and have more OH -, and also referred to as alkaline solutions base-solutions](http://images.slideplayer.com/25/7819040/slides/slide_5.jpg "Hydrogen ions from water water will self-ionize to a very small extent in pure water at 25°C, the [concentration] of H + ions/H 3 O + and OH - ions are equal – [H 3 O + ] = [OH - ] – both have a concentration of 1.0 x M acid solutions have a greater concentration of H + ions/H 3 O + than OH - ions basic solutions are opposite and have more OH -, and also referred to as alkaline solutions base-solutions")
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pH of 1 is 100x more acidic than pH of 3 pH of 4 is 1,000x more basic than pH of 1 pH of 6 is 10,000 less concentrated [H + ] than pH of 2 pH[H + ] ions in scientific notation [H + ] ions traditionally 01x10 0 1.0 11x10 -1 0.1 21x10 -2 0.01 31x10 -3 0.001 41x10 -4 0.0001 51x10 -5 0.00001 61x10 -6 0.000001 71x10 -7 0.0000001 81x10 -8 0.00000001 91x10 -9 0.000000001 101x10 -10 0.0000000001 111x10 -11 0.00000000001 121x10 -12 0.000000000001 131x10 -13 0.0000000000001 141x10 -14 0.00000000000001
![pH of 1 is 100x more acidic than pH of 3 pH of 4 is 1,000x more basic than pH of 1 pH of 6 is 10,000 less concentrated [H + ] than pH of 2 pH[H + ] ions in scientific notation [H + ] ions traditionally 01x x x x x x x x x x x x x x x](http://images.slideplayer.com/25/7819040/slides/slide_6.jpg "pH of 1 is 100x more acidic than pH of 3 pH of 4 is 1,000x more basic than pH of 1 pH of 6 is 10,000 less concentrated [H + ] than pH of 2 pH[H + ] ions in scientific notation [H + ] ions traditionally 01x x x x x x x x x x x x x x x")
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pHpOH[OH - ] ions in scientific notation [OH - ] ions traditionally 0141x10 -14 0.00000000000001 1131x10 -13 0.0000000000001 2121x10 -12 0.000000000001 3111x10 -11 0.00000000001 4101x10 -10 0.0000000001 591x10 -9 0.000000001 681x10 -8 0.00000001 771x10 -7 0.0000001 861x10 -6 0.000001 951x10 -5 0.00001 1041x10 -4 0.0001 1131x10 -3 0.001 1221x10 -2 0.01 1311x10 -1 0.1 1401x10 0 1.0
![pHpOH[OH - ] ions in scientific notation [OH - ] ions traditionally 0141x x x x x x x x x x x x x x x](http://images.slideplayer.com/25/7819040/slides/slide_7.jpg "pHpOH[OH - ] ions in scientific notation [OH - ] ions traditionally 0141x x x x x x x x x x x x x x x")
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pH [H + ] [OH - ] pOH
![pH [H + ] [OH - ] pOH](http://images.slideplayer.com/25/7819040/slides/slide_8.jpg "pH [H + ] [OH - ] pOH")
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pH meter measures the voltage difference between the acid inside the bulb and that outside converts voltage to pH must be calibrated and maintained
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