AcidBase Reactions Neutralization Reactions Type of acidbase reaction

Acid-Base Reactions

Neutralization Reactions Type of acid-base reaction Strong Acid + Strong Base----all OH- ions combine with H+ ions to give water molecules Produce water and a SALT, MX. A salt is an ionic compound. HX + MOH MX + H 2 O ACID + BASE SALT + WATER

Example 1: Na. OH(aq) + HCl(aq) Na. Cl(aq) + H 2 O(l) What are the spectator ions? What is the net ionic equation?

Example 1: continued Na. OH(aq) + HCl(aq) Na. Cl(aq) + H 2 O(l) Na+(aq)+ OH-(aq) + H+(aq)+ Cl-(aq) Na+(aq)+ Cl-(aq)+ H 2 O(l) What are the spectator ions? Na+ and Cl- What is the net ionic equation? OH-(aq) + H+(aq) H 2 O(liq)----always with strong acids and bases

Salts Ionic compounds Formed using cation from base and anion of acid Can have acidic or basic properties if one acid/base component is strong and the other is weak. Examples: Na. Cl, Na 2 SO 4, Mg. Cl 2

Example 2: Predict the products from the acid-base reaction between H 2 CO 3 + Sr(OH)2 Write the complete, balanced equation as well as the net-ionic equation.

Practice! Complete and balance the following acid-base reactions. Write the net-ionic equation as well: 1) HCl. O 4 + Na. OH 2) HBr + Ba(OH)2 3) HNO 3 + KOH 4) Ca(OH)2 + HNO 3 5) Mg(OH)2 + HCl

What are acid-base indicators? Contains a weak acid and its conjugate base Weak acid—one color Conjugate base—different color Changes color based on what solution (acidic or basic) it is placed in. Change color over a specific p. H range –transition interval Used when specific p. H measurements not needed, seen a lot with titrations

Common Indicators Phenolphthalein Litmus indicator Broad p. H range Litmus— Dye originating from lichens p. H < 4. 5 (red), p. H > 8. 3 (blue)

Buffers A mixture composed of a weak acid and its conjugate base OR weak base and its conjugate acid buffers” or reduces the affect of a change in the p. H of a solution Absorbs slight changes in p. H resulting from the addition of small acid/base amounts to water. Buffer capacity— indicates how much strong acid/base can be tolerated in a buffer solution before p. H changes Trait of buffer

Types of buffers 1) Acidic Buffers Formed from mixing a weak acid and its conjugate base p. H < 7 2) Basic Buffers Formed from mixing a weak base and its conjugate acid p. H > 7

Why are buffers important to us? Buffers present in our body keep fluids within a certain p. H range. Blood has a p. H range of approximately 7. 3 -7. 4. A buffer involving H 2 CO 3/HCO 3 - maintains the blood p. H

Homework: Additional p. H calculations worksheet