The pH scale
Acids produce hydrogen ions, H + \text{H}^+ H + , in aqueous solution.
Alkalis produce hydroxide ions, OH − \text{OH}^- OH −
The pH scale runs from 0 to 14 and measures how acidic or
alkaline a solution is
pH 7 is neutral; below 7 is acidic; above 7 is
alkaline
pH is measured with universal indicator (a colour matched against a
chart, giving an approximate pH) or a pH probe (a digital reading,
more accurate)
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The pH scale 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 ACIDIC NEUTRAL ALKALINE battery acid lemon juice vinegar rain water pure water baking soda soapy water oven cleaner pH measures the concentration of H⁺ ions. Acids are pH below 7 and produce H⁺ ions in solution; alkalis are pH above 7 and produce OH⁻ ions. Each step of one on the scale is a ten-fold change in concentration. The pH scale 0 to 14 coloured as universal indicator, red through green to purple, with example substances placed along it
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In the full topic
• The pH scale• Neutralisation• Strong and weak acids [Higher Tier]Read the free chemistry topics →