Kategorien: Alle - bases - acids - equilibrium

von Samia Bakr Vor 4 Jahren

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Acid-Base Equilibrium

The text discusses the critical aspects of acid-base equilibrium, focusing on the behavior and interaction of acids and bases in aqueous solutions. It highlights the process of titration, where the concentration of acids and bases can be determined using specific formulas.

Acid-Base Equilibrium

Acid-Base Equilibrium

Determining concentrations in titrations

stands for
Vb = volume of the base
Mb = molarity of the base
nb = amount of hydroxide ions that are given by the base per molecule
Va = volume of the acid
Ma = molarity of the acid
na = amount of hydrogen ions that are given by the acid per molecule
The concentration of titration:
na x Ma x Va = nb x Mb x Vb

Acids and Bases Combined Together

Water is generated when both are mixed
The equilibrium constant for water:

Kw = [H+][OH-] = 1.0 x 10-14 at 25oC

A very low amount of water dissociates into H+ and OH- ions because H2O is considered to be a constant factor
H+(aq) + OH- (aq) ⇌ H2O (l)
The chemical properties of acids can be neutralized by bases

Bronsted Lowry Theory

A pair with a strong base has a weak acid and a pair with a weak base has a strong acid
Every acid-base pairs can react to produce brand new conjugated acid and a brand new conjugated base
Water can be considered as acid and base
Bases are proton recipients
Acids are proton donors

Calculating pH for strong acids/bases

Considered a neutral substance when the pH is at 7
Considered a base when the pH is above 7
Considered an acid when the pH is below 7
When trying to find the concentration of [H+] and the pH is given. The formula would be:
pH formula is:
pH= -log [H+]

Arrhenius Theory

Developed the most common ways to state acids and bases
Swedish scientist

Relationship between Ka, Kb, and Kw

The sum of Ka and Kb is what results in the formation of constant water which would be Kw
The relationship between Ka and Kb is that they both depend on pressure and temperature
Kw = water constant
Kb = basicity constant
Ka = acidity constant

Calculating pOH for weak acids/bases

The formula then switched to leave the pOH value alone to become
pOH = 14 - pH
The pOH formula is used and the found pH value is subbed in
pH + pOH = 14
Find the concentration of OH- using this formula:
pOH = -log [OH-]
Find the pH value first using the pH formula:
[H+] = 10-pH

Acid

Common acids are
Acetic acid (CH3COOH)
Nitric acid (HNO3)
Sulphuric acid (H2SO4)
Hydrochloric acid (HCl)
Considered a weak acid when the acid barely ionizes

CH3COOH

Organic acids

Considered a strong acid when the acid ionizes completely

Al(OH)3

Fe(OH)3

Hydrogen gas is generated when an acid reacts with different metals like Zn, K, Na, Mg, and etc.
Tends to generate corrosion (corrosive)
When introduced to carbonates, a reaction would occur producing CO2 gas
Causes bromthymol blue to react and become yellow
Cause Litmus paper to react and become red
Generates a sour taste
Can change from a liquid to a solid
Dissolves in water to generate hydrogen ions (H+)

Base

Common bases are
Ammonium hydroxide (NH4OH)
Sodium bicarbonate (NaHCO3)
Sodium carbonate (Na2CO3)
Calcium hydroxide (Ca(OH)2)
Potassium hydroxide (KOH)
Sodium hydroxide (NaOH)
Considered to be a strong base, due to the fact that it is soluble when present around water molecules
Examples

NaOH

KOH

Properties are
Causes phenolphthalein to react and become pink
Causes bromthymol blue to react and become blue
Cause Litmus paper to react and become blue
Does not use metals to generate hydrogen
Tends to generate corrosion (corrosive) and is flammable
Able to react with an acid
Considered to be one of the best conductors for electricity
Generates a bitter taste
Is able to be in the form of a liquid and a solid
Dissolves in water to generate hydroxide ions (OH-)
Opposite of acids

Ledgend

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Formulas
Formula Indicators
Concept/Facts / Terminology
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