8 th Grade Science March 5, 2013

Roster Packets Lab Acids and Bases today (Yay!)

Page of Notes Please take out a paper and pencil/pen to take one page of notes on Acids and Bases This page will be page three in your packet It will count 5% extra credit this month toward your semester grade I will post it just in case you lose your notes

Acids Acids almost always have a hydrogen or two at the beginning of their formula: HCl - Hydrochloric Acid H 2 NO 4 - Nitric Acid HF - Hydrofluoric Acid H 2 SO 3 - Sulfuric Acid HC 2 H 3 O 2 - Acetic Acid

Acids When they are released in water (dissolved) they let go of this hydrogen atom and these H + ions make the solution acidic. pH < 7 There are strong acids: HCL, H 2 SO 3 and weak acids: HC 2 H 3 O 2

Acids Weak acids in your food taste sour. Examples? NOTE: In the lab, as in all labs, we do not ever smell or taste the chemicals we are testing.

Bases Bases almost always have an OH at the end of their formulas: Sodium Hydroxide – NaOH Potassium Hydroxide – KOH Ammonium Hydroxide - NH 4 OH Calcium Hydroxide - Ca(OH) 2 Magnesium Hydroxide - Mg(OH) 2

Bases When bases are dissolved in water, they release these OH - groups as ions that make the water basic. pH > 7 There are strong Bases: NaOH, Mg(OH) 2 and weak Bases: CaCO 4

Bases Weak bases in you foods taste bitter. Examples?

Neutral Pure water, H2O, is neither acidic nor basic. It is neutral: 7.0

pH pH is a measure of how acidic or basic a liquid is. It can be measured with pH indicators by dipping them in the liquid and comparing their color to a chart. It can also be measured electronically by a pH meter.

Ions Ions are charged particles. They can be positively or negatively charged. H+ and OH- are both ions. The more ions in the solution, the stronger acid or base it is. You will be measuring the concentration of ions by measuring the pH (1 – 14) of each liquid.