pH questions
pH worksheet
schmied/reid©2004
The Basics Name _________
of period ___
Acids and Bases Student # ___
There are many Acids and Bases in use in our world,
they can be helpful and they can be really harmful.
What is an Acid? Acids are chemical compounds with Hydrogen (Hydronium) ions (H+) that:
• Grabs, or accepts, electrons (OH- has an extra electron and is an ionic molecule)
• Taste sour, causes nervous system to activate.
• React with active metals (iron, tin etc.) to dissolve the metal and produce Hydrogen gas
• React with bases to form water and a salt
• Can damage your skin and cause pain soon.
What is a Base? Bases are chemical compounds with Hydroxide (Hydroxyl) ions (OH-) that:
• Grabs, or accepts, protons (H+ is a proton and an ion - non neutral atom)
• Taste bitter, usually don't feel pain until skin is exposed to air, then like a burn.
• Feel slippery or soapy to the skin ( soap is a base!)
• React with acids to form water and a salt
• Can damage your skin and don't usually cause pain right off!!
What is pH? pH is a measure of the amount of H+ ions and OH- in a solution.
If there are more H+ ions than OH- in a solution, the solution is an Acid.
If there are more OH- than H+ ions in a solution the solution is a Base.
If there are the same amount of OH- and H+ ions in a solution, its Neutral. (pH = 7)
What is a pH indicator? ts a solution of molecules that react with different concentrations of OH- ions (base) and/or H+ ions (acid) by changing shape. The color change you observe occurs because a different shaped molecule reflects different wavelengths of light, causing you to see a color change in the solution. The color change tells you what pH the solution is.
However: Most pH indicators do not always work with every pH! Each has a very specific range of pH it can detect. Sometimes scientists combine indicators so that they can detect all ranges of pH. This is called a universal indicator. The purpose of the lab is to discover what range of pH each indicator can detect.
You can see the different color changes one pH indicator makes from pH1- pH14.
(The base color of this inidicator is yellow, so it is only indicating from pH7-pH14)
However: pH indicators do not always work with every pH! Each has a very specific range of pH it can detect. The purpose of the lab tomorrow will be to discover what range of pH each indicator can detect and which indicators are better, natural, or manmade?
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