Review of Acids, Bases, & Salts

Arrhenius Acid Has H in the formula Produces H + as the only positive ion in solution

Formula of an Acid Inorganic – formula starts with H Organic – formula ends with COOH

Properties of Acids Sour Taste Electrolytes React with bases to form a salt + H 2 O Turn litmus RED React with most metals to produce H 2 (g)

Ionization of an Acid HCl  H + + Cl - HCl + H 2 O  H 3 O + + Cl - or

Arrhenius Base Has OH in the formula Produces OH - as the only negative ion in solution

Formula of a Base Has format MOH M is a metal

Properties of Bases Bitter Taste Slippery Feel Electrolytes React with acids to form a salt + H 2 O Turn litmus BLUE

Ionization of a Base NaOH  Na + + OH -

Ionization of NH 3 NH 3 + H 2 O  NH OH -

Formula of a Salt Metal + Nonmetal

Write the formula of potasium sulfate K + & (SO 4 ) 2- K 2 SO 4

Electrolytes Solutions conduct – they contain ions Acids (HX), bases (MOH), & salts (MX) are electrolytes

NONelectrolytes Solutions of covalent compounds (all nonmetals). They do NOT conduct.

Identify the electrolytes LiOH CH 3 COOH C 6 H 12 O 6 NaNO 3 H 2 SO 4 CH 3 OH Ca(OH) 2 HCl C 8 H 18 Al(OH) 3 HNO 3 CH 3 CH 2 COOH K 2 SO 4 CH 3 CHOHCH 3 CH 3 OCH 3 H 3 PO 4 Mg(OH) 2 CH 3 CH 2 OH Yes - B Yes - A No Yes - S Yes - A No Yes - B Yes - A No Yes - B Yes - A Yes - S No No Yes - A Yes - B No

pH scale 0-14 Acidic: 0 to 7, Neutral: 7 Basic: 7-14

Most acidic on pH scale pH = 0

Most basic on pH scale pH = 14

OH - Hydroxide ion

H+H+H+H+ Hydrogen ion or Proton

H3O+H3O+H3O+H3O+ Hydronium ion. Interchangeable with H +.

Acidic Solution [H + ]  [OH - ]

Basic Solution [OH - ]  [H + ]

If the pH changes from 3 to 5, how does the [H + ] change? The pH changes by 2, so the [H + ] changes by 10 2 or 100X. Since the pH went up, it became LESS acidic. The new solution has a [H + ] 100 times less than the original solution.

How can pH be safely tested? Instrumental – use pH meter Indicators – use a series of indicators to narrow down the pH range NOT Test acids with metals (NOT Cu, Ag, or Au)

Bronsted-Lowry Acid Proton Donor

Bronsted-Lowry Base Proton Acceptor

Bronsted-Lowry Acids & Bases HCl + H 2 O  H 3 O + + Cl -

Strong Acids & Bases Complete or almost complete ionization.

Weak Acids & Bases Ionization occurs only to a slight extent, a few percent.

Reactions of Acids with Metals Metal + Acid  H 2 (g) + salt

Zn(s) + HCl  ? Zn(s) + 2HCl  H 2 (g) + ZnCl 2

Al(s) + HCl  ? 2Al(s) + 6HCl  3H 2 (g) + 2AlCl 3

Neutralization Reactions Acid + Base  Salt + H 2 O

Net Ionic Equation for Neutralization Reactions H + + OH -  H 2 O

At neutralization Moles H + = Moles OH -

Molarity (M) Molarity = Moles solute Liters of soln

Titration Equation M a V a = M b V b This equation works when the number of H’s on the acid EQUALS the number of OH’s on the base!

Titration Equation n a M a V a = n b M b V b This equation works when the number of H’s on the acid does NOT equal the number of OH’s on the base! n a = number of acidic H’s in acid. n b = number of OH’s in base.

pH -log[H + ] or –log[H 3 O + ]

pOH -log[OH - ]

pOH + pH = 14

[OH - ] X [H + ] = 1.0 X

If the [H + ] = 1 X The pH = 2.The pOH = 3.The [OH - ] = X

Indicator Substance that changes color over a narrow pH range.

Molarity H 2 SO 4 Vs. Molarity H + H 2 SO 4  2H + + SO 4 2- [H + ] = 2[H 2 SO 4 ] 2M H 2 SO 4  4M H +

What is the concentration of a hydrochloric acid solution50.0 mL M KOH 20.0 mL of the HCl solution What is the concentration of a hydrochloric acid solution if 50.0 mL of a M KOH solution are needed to neutralize 20.0 mL of the HCl solution of unknown concentration? M a V a = M b V b X(20.0 mls) =.250M(50.0mls)

Acid 1.50 M Base ? M Final Volume Initial Volume Amount Used (1.50 M)(10.62 mls) = X(20.20 mls)