Chapter-15-tro

Chapter-15-tro - Chapter 15: Acids and Bases + Examples:...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 15: Acids and Bases Arrhenius acid : is a substance that produces H + ions in aqueous solutions Examples: HCl(aq) H + aq) + Cl - (aq) Cu 2+ ( aq ) + H 2 O( l ) CuOH + ( aq ) + H + ( aq ) Arhenius base : is a substance that produces OH- ions when dissolved in water Examples: NaOH(aq) Na + (aq) + OH - (aq) CN - ( aq ) + H 2 O( l ) HCN( aq ) +OH - ( aq ) Limitations : (1). These Arrhenius acid/base definitions apply to aqueous solutions only. (2). What happens when the solvent is other than water? (3). Does not explain why some substances are acidic or basic. New definitions of Acids/Bases Bronsted-Lowry Definition Lewis Definition Bronsted-Lowry Defintions : Acid is a substance that can donate a H + ion (or proton) Base is a substance that can accept a H + ion (or proton) Example: HCl( aq ) + H 2 O( l ) H 3 O + ( aq ) + Cl - ( aq ) Acid 1 Base 2 Acid 2 Base 1 1. Acid 1 and Base 1 are conjugate acid-base pair - Cl - is conjugate base of HCl
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Bronsted-Lowry Acids/Bases ..contd (3). Formula of conjugate base is obtained by subtracting H + from the formula of acid Formula of conjugate acid is obtained by adding H + to the formula of base (2). Acid 2, H 3 O + (aq), and base 2, H 2 O( l ), are conjugate acid-base pair H 3 O + ( aq ) is conjugate acid of H 2 O ( l ); H 2 O ( l ) is conjugate base of H 3 O + ( aq ) The above reaction is completely to the right. Then HCl ( aq ) is stronger acid than H 3 O + ( aq ) and H 2 O ( l ) is stronger base than Cl - ( aq ) Base 2 Acid 1 Example: HCl( aq ) + H 2 O( l ) H 3 O + ( aq ) + Cl - ( aq ) Acid 2 Base 1 Example 2 : CH 3 COOH( aq ) + H 2 O( l ) H 3 O + ( aq ) + CH 3 COO - ( aq ) Acid 1 Base 2 Acid 2 Base 1 Only 0.4% of CH 3 COOH ( aq ) is ionized at 1M conc. Therefore this reaction is almost to the left . CH3COO - ( aq ) is stronger base than H 2 O ( l ) CH 3 COOH ( aq ) is weaker acid than H 3 O + ( aq ) or H 3 O + ( aq ) is stronger acid than CH 3 COOH ( aq ) 3 3 - 3 - 3
Background image of page 2
Base 2 Acid 1 Example 3 : H 2 O( l ) + NH 3 ( aq ) NH 4 + ( aq ) + OH - ( aq ) Acid 2 Base 1 NH 4 + (aq) is conjugate acid of NH 3 (aq) or NH 3 (aq) is conjugate base of NH 4 + (aq) H 2 O( l ) is conjugate acid of OH - (aq) or OH - (aq) is conjugate base of H 2 O( l ) Bronsted-Lowry Acids/Bases ..contd Example 4 : HCl( in NH 3 ) + NH 3 ( l ) NH 4 + ( in NH 3 ) + Cl - ( in NH 3 ) Acid 1 Base 2 Acid 2 Base 1 Bronsted-Lowry approach is not limited to aqueous solutions Summary: Any molecule or ion that contains hydrogen can serve as an acid if a strong enough base is available to accept that hydrogen. Any molecule or ion can act as a base if a strong enough acid is in the vicinity to force a H + ion upon it.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Bronsted-Lowry Acids/Bases ..contd Example 1 : H 2 O( l ) + H 2 O( l ) H 3 O + ( aq ) + OH - ( aq ) Acid 2 Base 1 Acid 1 Base 2 H 2 O( l ) is conjugate acid of OH - (aq) or OH - (aq) is conjugate base of H 2 O( l ) H 3 O + ( aq ) is conjugate acid of H 2 O ( l ); H 2 O ( l ) is conjugate base of H 3 O + ( aq ) Amphoterism: A substance acts as an acid as well as a base
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 28

Chapter-15-tro - Chapter 15: Acids and Bases + Examples:...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online