Acid & Bases

    Cards (16)

    • pH is a measure of how acidic or alkaline a solution is, measured on a scale from 0 to 14 with low numbers being most acidic and high numbers being most alkaline.
    • The substance in your stomach which helps cure bacteria has a pH of around two.
    • Acid rain is around pH4.
    • Washing up liquid has a pH of around nine.
    • Bleach used to clean bathrooms has a pH of around 12.
    • pH can be measured using indicators, which are a group of chemical dyes that change color depending on the pH.
    • The most common example of an indicator is universal indicator, which gives the colors we've shown on the pH scale ranging from deep red at a very low and acidic pH to yellow green and then bluey purple as we increase the pH and it becomes more alkaline.
    • pH can also be measured using a pH probe connected to a pH meter by dipping the probe into a solution.
    • The benefit of the probe compared to an indicator is that it can be much more accurate and precise because it doesn't involve humans guessing shades or particular colors.
    • An acid is any substance that forms aqueous solutions with a pH of less than seven, as acids release hydrogen ions in water which make the solution acidic.
    • Bases, which we define as any substance with a pH greater than seven, form oH- ions in water which we call hydroxide ions.
    • If an acid and a base react together, it's a neutralization reaction which will always produce a salt and water.
    • Hydrochloric acid plus sodium hydroxide, the most common acid and base, will react to form sodium chloride which is a salt plus water.
    • Neutralization reactions can also be represented in terms of hydrogen ions and hydroxide ions, where h+ from the acid and oH- from the base combine to form H2O and because the acid and base have both been neutralized in these sorts of reactions the pH of the products should be seven because they're neutral.
    • Common acids include hydrochloric acid, sulfuric acid, and nitric acid.
    • Common bases are generally hydroxides or carbonates like sodium hydroxide or calcium carbonate.
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