Acids, Bases, and pH. Acids Release H + ions – so are called proton donors Contain H as the first element in the formula Taste sour Conduct electricity.

Acids, Bases, and pH

Acids

• Release H+ ions – so are called proton donors• Contain H as the first element in the formula• Taste sour• Conduct electricity• Corrosive – will steadily eat away at a

substance• Causes changes in an indicator

Bases

• Releases hydroxyl (OH)- ions – proton acceptor• Contains (OH)- as the last set of elements• Bitter taste, slippery feel• Conducts electricity• Corrosive• Causes changes in an indicator

Indicators

• Changes color in the presence of certain substances

• Examples– pH paper– Litmus paper (red or blue)– Phenolphthalein

Litmus

• In an acid, litmus paper will appear pink, in a base, it will appear blue

pH Paper

• Has a variety of colors indicating specific pH ranges for the material. From dark red for acids to dark blue for bases.

Acid or Base Strength

• The more likely a compound is to release H+ or (OH)- ions, the stronger it is.

• Even if a very strong acid or base (HCl or NaOH) is diluted with water, so it becomes less dangerous, it is still a strong substance.

Concentration

• The word concentration is a bit like the word crowded.

High concentration

Low concentration

Dilute vs Concentrate

High concentration

Low concentration

Concentrate

Dilute

pH Scale

• Measures concentration of H+ ions.• pH<7 - acidic• pH>7 - basic• pH = 7 - neutral

Title, Purpose, Materials, and Safety

Title – Acid activityPurpose – To gain experience determining the

pH of various substances using litmus paper and pH paper.

Materials – ph Paper, Litmus Paper, forcepsSafety – 1. Do NOT touch substances in beakers

2. You must wear goggles

Procedure

1. Gather Materials2. You will be assigned to one station, using the

forceps, dip a piece of red litmus paper into the substance at that station. Record color.

3. Repeat with blue litmus.4. Switch stations when told.5. One of the stations will involve pH paper, make

sure you do not use the litmus paper at that station.

Substance Red Litmus Color Blue Litmus Color Acid or Base?

Orange Juice

NaCl + H2O

Distilled H2O

Vinegar

Drano

Sugar + H2O

Aspirin + H2O

Tea

Lemon Juice

Ammonia

Baking Soda + H2O

H2O2

Maalox