An acid is a substance that produces hydrogen ions (H + ) when in solution with water Water (H 2 O)...
-
Upload
kelley-glenn -
Category
Documents
-
view
217 -
download
0
Transcript of An acid is a substance that produces hydrogen ions (H + ) when in solution with water Water (H 2 O)...
ACIDS AND BASES
Acids An acid is a substance that
produces hydrogen ions (H+) when in solution with water
Water (H2O) is made up of even amounts of H+ and OH- ions. Water is NEUTRAL because of this. When an acid dissolves in water, this changes the amount of H+ ions.
Examples of acids include hydrochloric acid, citric acid, acetic acid (vinegar)
Properties of Acids
The more H+ ions it produces, the more acidic the solution
Strong acids are very dangerous. They have a high H+ concentration.
Weak acids are less dangerous. They have a low H+ concentration
Acids
Acids occur naturally in many fruits Sore muscles and sour milk are
cause by the same acid (lactic acid) Acids add a tangy, sour flavours to
foods and drinks Some are deadly!
Bases A base is a substance that
produces hydroxide ions (OH-) when in solution with water.
When a base is added to water it increases the amount of OH- ions
Another word for basic is alkaline Example: Sodium hydroxide
(NaOH)
Properties of Bases
The more OH- ions it produces, the more basic (alkaline) the solution
Strong bases are as dangerous as strong acids. They have a high OH-
concentration. Similarly, weak bases are like weak
acids with a low OH- concentration
Bases
Bases are bitter-tasting compounds They have a slippery feel Bases are in most soaps, drain and
window cleaners. They can be found in many
pharmaceutical drugs Some bases are deadly!
pH Scale
pH means “power of the hydrogen ion”
A pH scale is a measure of the acidity of a solution
In pH the “p” is always lower case, even at the start of a sentence.
pH scale
The pH scale has a useful range of numbers between 0 and 14.
A solution with a pH of 7 is neutral (like water)
Below pH 7, a solution is acidic Above pH 7, it is basic
pH Scale
Paper testing Paper tests like litmus paper and pH
paper
pH meter
Tests the voltage of the electrolyte
Converts the voltage to pH Very cheap, accurate Must be calibrated with a buffer
solution
pH indicators Indicators are dyes that can be
added that will change color in the presence of an acid or base.
Some indicators only work in a specific range of pH
Once the drops are added, the sample is ruined
Some dyes are natural, like radish skin or red cabbage
Neutralization When an acid and a base react
together their pH becomes neutral.
Acid + base salt + waterEx: HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
This is a double displacement!
ACID-BASE NEUTRALISATION
Neutralisation Reaction:Acid + Base Salt + Water
Ex: HCl + NaOH NaCl + H2O
The acid and base neutralise each other creating a salt and water
Must be equal concentrations of acid and base
Actually a Double Displacement Reaction!
HNO3 + KOH KNO3 + H2O
HF + NaOH NaF + H2O
HCl + Ca(OH)2 CaCl2 + H2O 2 2
acid + base salt + water
1. Ba(OH)2 + H3PO4
2. HC2H3O2 + NaOH
3. H2SO4 + KOH
4. H2CO3 + NaOH
5. Na2CO3 + HCl