PH

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WHAT IS PH?

• The pH scale is a number scale used for measuring how acidic or basic a solution is

• FYI: pH stands for the potential hydrogen [H]+

THE PH SCALE

• The pH scale runs from 0 14

•0 7 is ACIDIC

•7 14 is BASIC

•7 is neutral

MORE PH SCALE

• Each unit of change represents a 10 times change in the degree of acidity or basicity

• In other words, if tomatoes have a pH of 4 and grapes have a pH of 3, then that means that grapes are 10 times more acidic than tomatoes

• If baking soda has a pH of 9 and bleach has a pH of 12, then bleach is 1,000 times more acidic than baking soda

EXAMPLE

• How much more acidic are bananas than milk?

10x

• How much more basic is ammonia than oven cleaner?

100x

• How much more acidic are lemons than water?

100,000x

• How much more basic are eggs than soap?

100x

RECOGNIZING ACIDS

• Acids are any solution with a pH of LESS THAN 7

• Chemical formulas for acids are usually written with an H on the left side of the formula

• Example: HCl (hydrochloric acid), H2SO4 (sulfuric acid)

•Acids form hydrogen (H+) ions when they dissolve in water

RECOGNIZING BASES

•Bases are any solution with a pH of MORE THAN 7

•Chemical formulas for bases are usually written with an OH on the right hand side of the formula

• Example: NaOH (sodium hydroxide), NH4OH (ammonium hydroxide)

•Bases form hydroxide (OH-) ions when they are dissolved in water

PRACTICE IDENTIFY IF THE FOLLOWING COMPOUNDS ARE ACIDS OR BASES:

• NaOH

• HCl

• HCH3COO

• NH4OH

• H2SO4

• Mg(OH)2

BASE

ACID

ACID

BASE

ACID

BASE

READING

Read pages 225 – 229 for Friday

WARNING/ ANNOUNCEMENT:

You are doing 2 labs tomorrow. • Absolutely NO food or drinks• Be ON TIME!