take out a scrap piece of paper… list 2 acids and 2 bases
TRANSCRIPT
Acids and Bases
Take out a scrap piece of paper…List 2 acids and 2 bases
By the end of today you should be able to…
Define acid, base, pH, and buffer
Describe why substances below a pH of 7 are acidic and why substances above a pH of 7 are basic
Describe 2 examples of pH in your body
GOALS
A solution is…◦A mixture where all the components are
evenly distributed (salt water)
When substances like salt or sugar dissolve in water the break up into ions ◦NaCl Na+ and Cl-
Sometimes we call ions electrolytes◦Like in Gatorade!
Recall…
A molecule of water (H2O) can break apart as well
H2O H+ and OH-
Number of positive ions = number of negative ions
So water is Neutral
Water
pH Scale – a measurement system used to show the amount of H+ in a solution
“potential hydrogen” 0 – 14; pH of 7 has equal parts H+ and OH-
That’s why H2O is neutral!
What if H+ and OH- weren’t equal?!
The pH Scale
Acid – a compound that forms H+ ions when in a solution
Contain more H+ ions than pure water Have a pH value below 7
The lower the pH, the stronger the acid
Taste sour or tangy
Acids
Milk = 6.6 Tomatoes = 4.5 Vinegar = 2.5 Lemon Juice = 2.0 Battery Acid = 1.0
Common Acids
Base – a compound that forms OH- ions when dissolved in a solution
Contain fewer H+ ions than pure water pH value above 7
The higher the pH the stronger the base
Make your skin feel slippery
Bases
Blood = 7.4 Baking Soda = 8.3 Ammonia = 11.0 Bleach = 12.6
Common Bases
pH Scale
Buffer – a substance that helps to prevent sudden changes in pH
This is especially useful in the body where some chemical reactions only work at certain pH levels
Buffer
We use acids and bases in every day life
◦ Many household cleaners are bases
◦ Some of the foods we eat are acids
◦ Farmers must maintain the pH of the soil
◦ We monitor the pH of our swimming pools
Why is pH Important?
Digestion◦Stomach acid has a pH of 1-2 ◦This is necessary to break down the foods
we eat
Blood◦Blood has a pH around 7.4◦pH plays an important role in the amount of
oxygen carried by your blood
pH in the Body
Enzymes◦pH is extremely important to enzymes◦Enzymes control almost all chemical
reaction in your body◦They will only work at specific pH levels!
pH in the Body