strong acids

Strong acids

All (100%) of the H ionize to H+

HCL, H2SO4, HNO3 are all strong acids

Strong Bases

All (100%) of the OH ionize to (OH)-

NaOH and KOH are strong bases

WEAK acids and bases

Not all the hydrogen ions or hydroxide ions come off (ionize) in solution

Carbonic acid and Phosphoric acids are weak

Acid Base Reactions

Acids + Metals

In lab we did an experiment with Zinc and acid:

Zn(s) + HCl (aq) H2(g) + ZnCl2 (aq)

Is this equation balanced? Balance it!What type of reaction is it?If we used copper instead of zinc, what would

happen? (hint: look at Table J)

Neutralization Reactions

Neutralization Reactions

Acid + Base water + a salt

This is true for any acid and base

Because water (pH = 7= neutral) is produced, the acid and the base are neutralized

Write Neutralization Reactions for…

Nitric acid + potassium hydroxide

Sulfuric acid + calcium hydroxide

Magnesium hydroxide and hydrochloric acid

Titration Equation

Remember: Molarity (M) = Moles/Liter

So…. moles = molarity x Liters

Titration Equation

In a neutralization reaction……

the number of moles of acid must be equal to the number of moles of base

(or the end result will not be neutral! )

Titration Equation

Therefore, in a neutralization reaction….

Moles of Acid = Moles of Base or Moles (A) = Moles (B)

Titration Equation

Since we know that Moles = molarity x Liter,We can substitute in for Moles

Moles of Acid = Moles of BaseMolarity(of acid) x liters(of acid) = Molarity(of base) x Liters

(of base)

Titration Equation

We simplify this equation: (see Table T)

Ma x Va = Mb x Vb

Where Ma = molarity of acid Va = volume of acid (in liters) Mb = molarity of base Vb = volume of base (in liters)

Ma x Va = Mb x Vb

What is the concentration of HCl if 50 ml of a 0.25M KOH are needed to neutralize 20 ml of HCL solution?

Ma = ?Va = 20 mlMb = .25MVb = 50 ml

Ma x .02L = .25M x .05L

Ma x Va = Mb x Vb

What is the concentration of HCl if 50 ml of a 0.25M KOH are needed to neutralize 20 ml of HCL solution?

Ma x .02L = .25M x .05L

Ma = .25M x .05L .02L

Ma = .625M

Titration

is used to very accuratelymeasure the volumesof acids and basesduring a neutralizationreaction

Phenolphthalein indicator is clear in acids, pink in bases

Neutralization is reachedwhen the clear solution turns a pale pink

If solution turns a dark pink, too muchbase has been added and the solution is now basic, not neutral

pH

pH

• pH = 7 Neutral (pure water)

• pH 0-6 Acidic

• pH 8-14 Basic

Indicators: Table M

• Change colors in the presence of acids or bases

• Phenolphthalein = clear in acids, pink in bases

• Litmus = red acid Blue Base