Unit 9: Acids and Bases

What makes something and ACID or BASE?

An Acid is a PROTON DONOR

A Base is a PROTON ACCEPTOR

Hydrogen

 atom with only 1 proton and 1 Electron…

If we take away the Electron, we only have a Proton left

We call this H^{+ (a negative charge)}

ACIDS (abundant donors)

Acids are proton DONORS, meaning they have more hydrogen than they need and can be easily separated from it…

Strong Acids

A strong Acid is one that COMPLETELY gives up all its Hydrogen when it reacts

Ex of Strong Acid/Bases

691 × 424

Weak Acid

Rule of thumb: if it’s NOT a strong acid, then its a weak acid

Weak acids will not give up all their proton donor ions attached to their chemical formula

Proton acceptor

Bases are Proton ACCEPTORS meaning they will easily bond with Protons (H⁺) 

Weak Bases

Weak bases will not give up all their proton acceptor ions attached to their chemical formula

Neutralization

Acids and Bases will cancel eachother out…resulting in the formation of water and a salt.

(If we pour HCl (an acid) into NaOH (a base), the ions will split into their individual components)

Remember: Acid/Base (Zuma)

Water… H20

Water: Made of H⁺ and OH^- → H₂O (PureWater is perfectly neutral )

Water can act as EITHER an Acid OR a Base (depending on the situation)

pH Scale ( potential hydrogen )

(ion concentration)

It is based upon the Molarity concentration (remember last unit) of Hydrogen Ions

We use brackets around an atom or ion to denote concentration so:

[H⁺] = Concentration of hydrogen Ions

We use brackets around an atom or ion to denote concentration so:

THE pH and pOH Scales

pH Scale

Water is neutral and has a pH (and pOH) of 7

Acids are 0-< 7 (lower number = stronger acid)

Bases are > 7-14 (higher number = stronger base)

pOH Scale

Water is neutral and has a pH (and pOH) of 7

Bases are 0 - < 7 (lower number = stronger Base)

Acids are > 7-14 (higher number = stronger Acid)

Measuring pH

tool called litmus paper to get a general idea of the pH of a solution

Litmus turns red in Acid and Blue in Base

A Universal Indicator shows more depth with a wider range of colors for different pH ranges/values

Measuring Universal Chart

pH and pOH relationship

pH + pOH = 14

[H⁺] x [OH^-] =1 x 10^-14  based on SELF IONIZATION OF WATER

SELF IONIZATION OF WATER

-Where water will donate and accept protons within itself

This reaction happens constantly and only from a brief moment

Logs?…

The pH scale is Logarithmic which means each number you increase by is 10 times greater than the number below it in terms of concentration

It is also an inverse scale:

The lower you go on the scale, the higher the concentration of hydrogen ions

Example Concentrations

Each number on the pH scale represents a NEGATIVE power of 10 (values that are less than one)

A pH of 7 means [H⁺]= 1 x 10^-7 

pH and Acid

Acids have LOW pH (less than 7)… High concentration means a LOW negative exponent such as 10^-1 or 10^-2

That would correspond to a pH of 1 or 2

pH of Bases*

pH of above 7… A low concentration means a LARGE negative exponent like 10^-12 or 10^-13

This would be like a pH of 12 or 13

*Bases can also be called Alkali

pH and [H⁺] Relationship/ pOH and [OH^-] Relationship

We can use the following equations for pH value:

pH= -log[H⁺]      or         [H⁺]=10^-pH    (thats 10 to the negative pH power)

We can use the following equations for pOH value:

pOH= -log[OH^-]      or         [OH^-]=10^-pOH    (thats 10 to the negative pOH power)

Know examples