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Entrance Questions

Entrance Questions. On the pH scale what number is neutral pH Which number range is an acid Which number range is basic. Acids and Bases. Acids. An acid is a substance that has a high concentration of hydrogen ions (H + ) When mixed with water they form hydronium ions (H 3 O + )

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Entrance Questions

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  1. Entrance Questions • On the pH scale what number is neutral pH • Which number range is an acid • Which number range is basic

  2. Acids and Bases

  3. Acids • An acid is a substance that has a high concentration of hydrogen ions (H+) • When mixed with water they form hydronium ions (H3O+) • This is called ionizing

  4. Acid properties • Strong acids • Ionize completely in water • When in water conduct electricity very well • This is called an electrolyte • Weak acids • Incompletely ionize in water • Do not conduct electricity in water well • All acids cause for a sour taste and can be very harmful in concentrated form

  5. bases • Some bases contain hydroxide ions (OH-) • Bases that do not have hydroxide ions will react with water to form hydroxide ions. • Also known as alkalinity • All bases have a bitter or soapy taste, and feel slippery when mixed in water.

  6. Bases properties • Strong bases • Ionic compounds • Metal ion and hydroxide ion • Hydroxide ions dissociate (separate) in water • Weak bases • Ionic compounds that do not contain a hydroxide ion but form one when mixed with water

  7. pH scale • Measures the concentration of hydronium ions • More hydronium means more acidic • Less hydronium means more basic • Each number indicates a 10x change

  8. Finding pH based on Molarity • Molarity is how many moles of the solute are in 1L of solution • Meaning a higher molarity will have a higher concentration lower molarity will have a lower concentration • What’s a mole? • A mole is the atomic mass of the element One mole of Sulfur is 32.07 grams

  9. If the molarity of a substance is 0.001 M • Step 1) put this number in scientific notation • 1.0x10-3 M • Step 2) look at the exponent • It is -3 • Step 3) take the negative value of this • -(-3) = 3 • Step 4) the pH is that value • pH = 3 (its acidic) • *** important this only works with monoprotic acids and when the molarity is 1.0x10any power An acid that donates only one H to water when it dissociates

  10. Entrance questions • When you hear hydronium you think __________ • Some thing that is acidic would have a pH of _________ • A substance with a pH of 2 is how many times more acidic than a substance with a pH of 4? _________ • A substance that is a strong base has what two parts making it up? __________ and ___________ • A monoprotic acid like HCl has a molarity of .000001 M what is its pH? • A solution of HCl has a pH of 2 what is its molarity? • How many grams are in 1 mole of sulfuric acid, H2SO4

  11. Key points • pH scale ranges from 0 (very acidic) to 14 (very basic) • pH 7 is neutral • Each number indicates a 10x change in pH • pH of 4 is 10x more acidic than 5, and 100x more acidic than 6 • Acids have hydronium H3O+ • Bases have hydroxide OH- • Dissociate means to break down into its pieces • Example HCl dissociates in water to form H+ and Cl- ions • Strong acids and bases dissociate completely in water • To find pH based on molarity it is the negative of the power exponent in scientific notation • Ie 1.0x10-5 M has a pH of 5

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