Acids and Bases They don’t blow up in your faces!

Acid Definition Acids are substances that contain an H + ion. An H + ion is a hydrogen atom with a positive electrical charge. The H + is usually listed first in the chemical name of an acid. (HCl, H 2 SO 4 )

Acid Properties Acids are usually extremely corrosive. –They react with metals to form hydrogen gas Acids taste sour, tangy, hot and fruity. Acids conduct electricity

Acids in your house Most fruits have acids –Citrus fruits are acidic from CITRIC ACID Soda that is carbonated is acidic Vinegar! (acetic acid)

Arrhenius Acids Acids dissociate (break into ion pieces) when they are dissolved in water. One of these pieces is always Hydrogen ion (H + ). Dissociation of HCl HCl  H + + Cl -

Strong Acids Strong acids are strong electrolytes Strong acids dissociate completely into hydrogen ions and anions Weak acids do not conduct electricity as well because they do not dissociate completely into ions!

Hydronium ions Hydronium ions (H 3 O + ) are just hydrogen (H + ) ions attached to water H + + H 2 O  H 3 O + When hydrogen ions are in water, this happens!

Base Definition (1) Bases are substances that contain a hydroxide ion ( OH - ). The OH - is usually listed last in the chemical name of a base. Examples (NaOH, Ca(OH) 2 ) There are some bases that need a better definition!

Arrhenius Base Bases form hydroxide ions when put into water. NH 3 is a base because it makes NH 4 + and OH – when it is added to H 2 O. Bases with OH in them (like NaOH) dissociate to form OH –.

Base Properties Bases can be corrosive. –They react well with organic things like skin! Bases are bland, slippery, slimy, or sticky. If you get a base on your fingers, it will feel slippery. YOUR SKIN IS COMING OFF!

Base Properties Bases also conduct electricity. Do you know why?

Bases in your house SOAP – feels slimy, doesn’t it? Lots of cleaning things –Ammonia –Drano

Indicators Substances that respond to the H + or OH - ions and show a different color depending on the pH. Most indicators have one color when they are in acid, and another in base. Each changes at a specific pH

The pH scale The pH scale shows how acidic a solution is. It goes from 0-14 Acids have low pH Bases have high pH 7 is neutral, not acid or base

pH pH depends on the concentration of hydrogen ion in the solution –Lots of hydrogen ion = low pH –Very little hydrogen ion = high pH What things from home would you like to test?

More resources You should READ pp and Do these problems –P. 549 # 1, 2, 4, 5