Easily Observable A. Acids taste sour, bases taste bitter B. Bases feel slippery (soap) C. Acids & Bases react with each other
Acid-Base Indicators D. Acids & Bases cause certain dyes to change color. These dyes are called acid- base indicators. E.. Example: Litmus changes red in acid & blue when exposed to bases F. Red cabbage, radishes & rose petals
Macroscopic cont. G. Reactions with metals & carbonates 1. Acids react with metals to form H 2 **acids cause metals to corrode 2. Acids react with carbonates to form CO 2 & water. **This causes pollution & the wearing away of limestone & marble.
A. Acids and Bases Acids have formulas that begin with an “H”. They have an acidic hydrogen- a H atom that can be transfered to water and is written 1 st in a formula. 1 acidic H = monoprotic, ex: HCl 2 acidic H = diprotic, ex: H 2 SO 4 Acids are proton donors Produce hydronium ions [H 3 O +]
A. Acids and Bases The general reaction for an acid dissolving in water is
Bases often have formulas that end in OH Bases are proton acceptors Bases produce hydroxide ions [OH - ]
A. The pH Scale Neutral pH = 7 [H 3 O + ]=[OH - ] Acids pH<7 [H 3 O + ]>[OH - ] Bases pH>7 [H 3 O + ]<[OH - ]
A. The pH Scale Because the pH scale is a log scale based on 10, the pH changes by 1 for every power of 10 change in the [H + ].
B. Acid Strength Weak acid – most of the acid molecules remain intact (HC 2 H 3 O 2 )
Common Acids Strong acids – Sulfuric acid, H 2 SO 4 – Hydrochloric acid, found in gastric juice, HCl – Nitric acid, HNO 3 Weak acids –Acetic Acid, found in vinegar, HC 2 H 3 O 2, –Carbonic Acid, found in soft drinks, H 2 CO 3 –Phosphoric Acid, H 3 PO 4
Common Bases Strong bases are Group 1 or 2 metals bonded with hydroxide. ex: Sodium Hydroxide - NaOH Potassium Hydroxide – KOH Calcium Hydroxide - Ca(OH) 2 Weak Bases Household ammonia = Ammonium Hydroxide = NH 4 OH Ammonia= NH 3
C. Water as an Acid and a Base Water is amphoteric – it can behave as either an acid or as a base Ionization of water –Concentration of hydronium and hydroxide are equal
C. Water as an Acid and a Base Product of [H 3 O + ] and [OH ] is always constant.
B. Measuring pH Indicators – substances that exhibit different colors in acidic and basic solutions –In an acid solution the indicator will be in the HIn form. –In a basic solution the indicator will be in the In form.
C. Calculating the pH of Strong Acid Solutions Determine the [H + ]. pH = log[H + ]