Chemistry Chapter 15: Acids and Bases React
pH of a healthy lake
6.5, but some lakes have a pH as low as 4.0
Burette
A long, calibrated tube with a valve at the bottom.
Brønsted-Lowry Model
A model of acids and bases in which an acid is a hydrogen-ion (a proton) donor and a base is a hydrogen-ion (a proton) acceptor.
Neutralization Reaction
A reaction of an acid with a base in aqueous solution to produce water and a salt. Acid + Base --> Salt + Water
Standard Solution
A solution of known molarity used in a titration.
Buffer
A solution that resists changes in pH when moderate amounts of acids and bases are added together. Buffers contain ions or molecules that react with hydroxide or hydrogen ions if one of these ions is introduced into the solution.
Examples of Insoluble Hydroxide Antacids
Aluminum Hydroxide (Al(OH)3) Magnesium Hydroxide (Mg(OH)2)
Ionic Equation
An equation in which substances that primarily exist as ions in solutions are shown as ions.
What must be the case for the acid-base reaction to reach completion?
At least one of the reactants must be strong.
How are buffer solutions prepared?
Buffer solutions are prepared by using a weak acid with one of its salts or a weak base with one of its salts.
Examples of Carbonate-Based Antacids
Calcium Carbonate (CaCO3) Magnesium Carbonate (MgCO3) Sodium Hydrogen Carbonate (NaHCO3) Potassium Hydrogen Carbonate (KHCO3)
Antacids
Contain bases which as buffers to combat stomach problems associated with acid indigestion.
What are the types of blood buffers?
Dissolved CO2. When dissolved in water, it produces carbonic acid (H2CO3) Hydrogen Carbonate ion (HCO3-)
Weak Acid-Weak Base
Generally do not play an important role in acid-base reactions because neither make very many ions for there to be a H+ transfer.
What is the net ionic equation for all strong acid-strong base reactions?
H+(aq) + OH-(aq) --> H2O(l)
When are blood buffers used?
If something happens to increase the hydroxide ion concentration in your blood, carbonic acid reacts to lower the hydroxide concentration and keep the pH from increasing. If hydrogen ions enter the blood, hydrogen carbonate ions react to keep the pH from decreasing.
In an acid-base reaction, what does water act as?
In an Acid-Base reaction, water can act as either an acid or a base, depending on the reaction.
What is required in an Acid-Base reaction?
In an acid-base reaction there must always be two substances to transfer, so for every acid (an H+ donor), there must be a base (an H+ acceptor).
Types of Antacids
Insoluble Hydroxide Antacids Carbonate-Based Antacids
What is the reason we write ionic equations?
Ionic equations are the best way to model the submicroscopic behavior of an acid-base reaction because it shows the reactants and products as the actually exist in solution.
Spectator Ions
Ions that are present in the solution but do not participate in the reaction. Spectator ions are important components of an overall equation, but they do not directly participate in the chemical reaction. Spectator ions that are common to both sides can be subtracted from the equation. This is done so that the reactants and products that actually change can be seen more clearly.
What is the best way to know when a titration endpoint has been achieved?
It is best to use an indicator. Different types will use different indicators because the endpoint pH will be different depending on the type of acid-base reaction. Strong Acid-Strong Base a neutral solution is produced and Bromthymol Blue is used to find the endpoint. Strong Acid-Weak base a slightly acidic solution is produced and Methyl Red is used to find the endpoint. Weak Acid-Strong Base as slightly basic solution is produced and phenophthalein is used to find the endpoint.
List of Strong Bases
Lithium Hydroxide (LiOH) Sodium Hydroxide (NaOH) Potassium Hydroxide (KOH) Calcium Hydroxide (Ca(OH)2) Strontium Hydroxide (Sr(OH)2) Barium Hydroxide (Ba(OH)2)
List of Strong Acids
Perchloric Acid (HClO4) Sulfuric Acid (H2SO4) Hydiodic Acid (HI) Hydrobromic Acid (HBr) Hydrochloric Acid (HCl) Nitric Acid (HNO3)
Examples of a salt
Sodium Chloride (NaCl) Potassium Chloride (KCl) Ammonium Nitrate (NH4NO3) Iron (II) Phosphate (Fe3(PO4)2)
What are the three most common types of acid-base reactions?
Strong Acid-Strong Base Strong Acid-Weak Base Weak Acid-Strong Base
Types of Acid-Base Reactions
Strong Acid-Strong Base Strong Acid-Weak base Weak Acid-Strong Base Weak Acid-Weak Base
Net Ionic Equation
The equation that results when ions common to both sides of the equation are removed, usually from an ionic equation. Net ionic equations describe what is really happening at the submicroscopic level. Net ionic equations show why the reaction of an acid and a base are called neutralization reactions, because the hydrogen ion from the acid reacts with the hydroxide ion from the base to form water, which has a neutral pH.
Salt
The general term used in chemistry to describe the ionic compound formed from the negative part of an acid and the positive part of a base.
pH of the stomach
The normal pH of the stomach is about 2.5 and it must be like this to properly digest food.
pH of Blood
The pH of blood is slightly basic, about 7.4. If a person is healthy, pH does not vary by more than one-tenth of a pH unit. Blood is an example of an effective buffer.
Titration
The process of determining the molarity of an acid or base by using an acid-base reaction where one reactant is of known molarity.
Why is a neutralization reaction called a neutralization reaction?
The properties of both the acid and the base are diminished or neutralized when they react.
What affects the pH of the final product in an acid-base reaction?
The strength of the acids and bases in the equation will affect the pH of the final product. Strong Acid-Strong Base = Neutral pH (7) Strong Acid-Weak Base = pH less than 7 (Acidic) Weak Acid-Strong Base = pH greater than 7 (Basic)
Does water ionize?
Water does not ionize much, so it is indicated as a molecule rather than as H+ and OH- ions.
What is the acid-base reaction that is almost never used?
Weal Acid-Weak Base
