* 0-6.9 being acidic
* 7 being neutral
* 7.1-14 being basic (or alkaline)
Here's what makes pH go up or down:
Factors that increase pH (make it more basic):
* Adding a base: Bases, like sodium hydroxide (NaOH), have a high pH. When added to a solution, they increase the concentration of hydroxide ions (OH-) which causes the pH to rise.
* Removing an acid: Removing an acid from a solution will also increase the pH because the concentration of hydrogen ions (H+) is reduced.
* Adding a salt of a weak acid and a strong base: For example, sodium acetate (NaCH3COO) dissolved in water will cause the pH to rise because the acetate ions (CH3COO-) react with water to form hydroxide ions (OH-).
* Temperature changes: Some substances change their pH with temperature. For example, pure water becomes slightly more basic as temperature increases.
Factors that decrease pH (make it more acidic):
* Adding an acid: Acids, like hydrochloric acid (HCl), have a low pH. When added to a solution, they increase the concentration of hydrogen ions (H+) which causes the pH to drop.
* Removing a base: Removing a base from a solution will also decrease the pH because the concentration of hydroxide ions (OH-) is reduced.
* Adding a salt of a strong acid and a weak base: For example, ammonium chloride (NH4Cl) dissolved in water will cause the pH to drop because the ammonium ions (NH4+) react with water to form hydrogen ions (H+).
* Temperature changes: Similar to the above point, some substances change their pH with temperature. For example, pure water becomes slightly more acidic as temperature decreases.
In summary:
The pH of a solution depends on the concentration of hydrogen ions (H+) and hydroxide ions (OH-). Adding substances that increase the concentration of H+ ions will decrease the pH (make it more acidic). Conversely, adding substances that increase the concentration of OH- ions will increase the pH (make it more basic).
