Class #100: Intro to Acids and Bases

AIM: Students will understand that acids and bases
dissolve to form specific ions in solutions.

Class #100

Class #100 Do Now

A student adds solid KCl to water in a flask. The flask
is sealed with a stopper and thoroughly shaken until
no more solid KCl dissolves. Some solid KCl is still
visible in the flask. The solution in the flask is

A) saturated and is at equilibrium with the solid KCl

B) saturated and is not at equilibrium with the solid KCl

C) unsaturated and is at equilibrium with the solid KCl

D) unsaturated and is not at equilibrium with the solid KCl

You will see and answer this question on the next slide!

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Common items that contain acids and bases

Acids

● Vinegar
● Lemon Juice
● Stomach acid
● Soda

Bases

● Baking soda
● Laundry Detergent
● Toothpaste
● Bleach

​

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Characteristic Properties of Acids

● Dilute solutions of acids (like vinegar,

lemon juice, etc.) have a sour taste

● Concentrated acids burn skin, eat holes

in clothing, and corrode metal

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Characteristic Properties of Bases

● Bases have a bitter taste

● Bases have a slippery or soapy feeling

● Strong bases can burn skin

● Bases cause acid- base indicators to

change color

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Acids and Bases cause acid-base indicators to

change color

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Remember how we saw that ionic compounds (salts)

break apart into positive and negative ions when

they dissolve in a solvent?

The word we use for breaking apart into
ions is “dissociation”

●

Example:

“Ionic compounds dissociate in water.”

7

Electrolyte

A substance that dissociates into ions (particles with
electrical charges) when it is dissolved in water or body
fluids.

● Because of these negative and positive charges,

electrolytes can conduct electricity when dissolved in
water

Salts are electrolytes because they dissociate into ions when

dissolved in water

8

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Acids and Bases also dissociate into ions, just like Salts

…..let’s see how….

Table K: Common Acids

In your Chemistry Reference Tables

Table K: Common Acids

Hey, did you
notice that
the acids all

have H in their

formulas?

That must

mean

something,

right???

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​Circle the H at the

beginning of each

formula in your notes!

Table L: Common Bases

Table L: Common Bases

Hey, did you
notice that
most of the
bases have
OH in their
formulas, and

the word

‘hydroxide’ in
their names?
That must

mean

something

too.

​That must

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​Circle the OH and the word "hydroxide" in the table in your notes!

Acids produce H+ ions in solution

Acid molecules DISSOCIATE (come apart) in water
●

When they dissociate, this produces the
positive hydrogen ion

Example: Hydrochloric Acid

The HCl molecule dissociates in water
into a positive hydrogen ion (H+) and a
negative chloride ion (Cl- )

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(Most) Bases dissociate in water to produce

hydroxide (OH –ions)

Example:
Sodium Hydroxide

The NaOH molecule
dissociates in water into
a negative hydroxide ion
(OH —)and a positive
sodium ion (Na+ )

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There are a couple of different scientific definitions of acids

and bases.

One of the first definitions was
developed by Svante Arrhenius, a
Swedish chemist.

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Arrhenius Acid: Substance whose water
solution contains the hydrogen ion as the
only positive ion.

Svante Arrhenius

** The H+ ion (which is just a
proton) often combines with a
water molecule to create H3O+.
This is called a hydronium ion.

H+ ion + water molecule hydronium ion

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Arrhenius Base:A substance that produces

hydroxide ions(OH- ) when dissolved in

water

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Some important words

We use the word acidic to
describe solutions
containing acids:

“Lemons are acidic.”

“This is an acidic solution”

We use the word “basic”OR the
word “alkaline” to describe
solutions containing bases.

“A solution containing NaOH is
basic.”

“Bleach is an alkaline
substance.”

Acidic Basic / Alkaline

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