pH
What is the ph range of a basic/alkaline substance?
>7
What is a buffer?
Buffers are solutions that keep a steady pH; they are able to resist pH changes.
What is the strong acid you need to remember?
HCl - hydrochloric acid
Is a Bronsted ACID a H+ donor or acceptor?
H+ donor
What is the pH range of an acidic substance?
<7
How does buffering work?
Buffers contain chemicals that absorb added hydrogen ions H+ or replace lost hydrogen ions H+ as a stress is applied so [H+] stays steady.
What is the strong base you need to remember?
NaOH - sodium hydroxide
Is a Bronsted BASE a H+ donor or acceptor?
H+ acceptor
What is the pH of a neutral substance?
7
What is an indicator?
An indicator is a substance that changes color depending on the solution pH.
i.e. a litmus strip has indicator in it that will change blue or red based on the pH of a solution
Do ACIDS release hydrogen ions or hydroxide ions when dissolved in water?
H+ - hydrogen ions
What is the definition of a conjugate pair?
A Bronsted acid and a Bronsted base pair differing by one H+
i.e. HF/F-, H2O/H3O+, HCl/Cl-
If a substance has a [H3O+] concentration of 1x10-4 what is the pH of the substance? Is the substance acidic, basic, or neutral?
pH = 4, acidic
What disassociation mean?
What does ionization mean?
To break apart.
To make ions
i.e. when an acid breaks apart it separates into separate parts that are ions
Do BASES release hydrogen ions or hydroxide ions when put into solution?
OH- - hydroxide
What is the difference between a weak acid and a strong acid?
A strong acid will complete a reaction with water and completely ionize.
HCl + H2O -> H3O+ + Cl-
A weak acid will not complete a reaction with water and is incompletely ionized. These reactions are reversible.
HF + H2O ⇌ H3O+ + F-
If a substance has a pH of 9, what is the [H3O+] and [OH-]?
[H3O+] = 1x10-9
[OH-] = 1x 10-5
**Remember - If you multiply the concentration of hydronium ions (H3O+) times the concentration of hydroxide ions (OH-) you get 1 x 10-14
[H3O+][OH-] = 1 x 10-14
How do you know if a substance is an ion or that ionization is occuring?
Look for the positive and negative charges.
i.e. F-, Mg2+, NH4+, H3O+
What happens during a neutralization reaction?
A reaction between an acid and a base to form a salt and water.
acid + base → salt + H2O
HBr + KOH → KBr + H2O
In the following reactions, identify the conjugate pairs:
CH3COOH + HPO42- → CH3COO- + H2PO4-
There are two conjugate pairs:
CH3COOH, CH3COO- and HPO42-, H2PO4-