Acids and Bases - Topic 8

What is a Brønsted-Lowry acid?

A proton (H⁺) donator

What is a Brønsted-Lowry base?

A proton (H⁺) accepter

What is a amphiprotic species?

A substance that can act as both a Brønsted-Lowry base and acid

What is a conjugate acid-base pair?

A pair of species differing by a single proton (H⁺)

What are the two main classifications of acids and bases?

Arrhenius and Brønsted-Lowry acids and bases

What is an Arrhenius acid?

A substance that ionizes in water to produce H⁺ ions

What is an Arrhenius base?

A soluble base that produces OH⁻ ions

What was the main limitation to Arrhenius’s theory?

Arrhenius’s theory did not explain reactions such as ammonia and hydrogen chloride gas, as ammonia acts as a base yet does not contain hydroxide ions

What was the earliest theory about acids?

One of the earliest theories was by Antoine Lavoisier, who proposed that oxygen was present in all acids and was the source of their acidic properties

Why are incorrect theories still important to science?

Theories, even if incorrect, still serve to encourage scientific curiosity. Additionally, new scientific discoveries are frequently made from the testing of theories over time, meaning many modern theories are directly thanks to continuing scientific testing.

How is science present in all forms of society?

Even basic scientific terms like “litmus” and “acid test” are used as figures of speech, representing science’s presence even in the everyday language of most people. It represents that science is often used to add credibility to a myriad of situations because the scientific method is seen as a rigorous process removed from bias

What is the alternate presence of H⁺ in an acid base reaction?

It could be present within the hydronium ion, H₃O, which is formed when a water molecule forms a coordinate bond with a proton

What does it mean to be monoprotic, diprotic, or triprotic?

This refers to the number of times a substance can undergo an acid-base reaction

What is a strong acid?

A substance assumed to undergo complete dissociation in water

What is an example of a strong acid?

Hydrogen chloride, HCl

What is a weak acid?

An acid that undergoes only partial dissociation in water, and will establish an equilibrium. A solution of a weak acid is only a weak electrolyte

What is the most common example of an amphiprotic species?

Water, H₂O

What type of species commonly act as amphiprotic?

Any polyprotic series

Why do 2-amino acids work as amphiprotic?

Since 2-amino acids contain a weakly acid carboxyl group and a weakly basic amine group, the compound acts as an acid in a strong base, but as base in a strong acid

In which reactions are salt and water produced?

Exothermic neutralization reactions

How are theories modified over time?

As more evidence is observed through qualitative and quantitative data which establishes patterns, leading to redefining of pre-existing theories to match the most recent evidence

What are the main properties of acids?

They taste sour, have a pH of under 7.0, have red litmus tests, are colourless in phenolphthalein, and is red in methyl orange

What are the main properties of bases?

They taste bitter, have a pH of over 7.0, have blue litmus tests, are pink in phenolphthalein, and is yellow in methyl orange

What do acids usually react with?

Metals, metal oxides, hydroxides, hydrogen carbonates, and carbonates

What is a salt?

A compound composed of an anion and cation

What is the basic reaction for an **acid + metal**?

acid + metal → salt + hydrogen

What changes the amount of hydrogen released and salt produced by a neutralization reaction?

The amount and rate at which hydrogen is produced is dictated by the strength and concentration of the acid. The salt depends on what specific acid was used

What is the basic reaction of an **acid + base**?

acid + base → salt + water

What is the basic reaction for an **acid + metal carbonate/metal hydrogen-carbonate**?

acid + metal carbonate/metal hydrogen-carbonate → salt + carbon dioxide + water

What is a titration?

A volumetric analysis technique that involves a reaction between a substance of unknown concentration with a standardized solution.

What are some ways that a titration can be monitored?

A coloured indicator, a pH probe, just fuckin guessing

What is Occam’s razor?

A blueprint for scientific theories, saying that they should be simple while maintaining a high capacity for gaining understanding

How is pH a good example of the application of Occam’s razor?

The pH scale is a very effective method of representing a continuous range of hydrogen ions as simple numbers for ease of interpretation. The pH scale clearly distinguishes between acids, neutral solutions, and basic solutions

What mathematical function can represent the pH scale?

A logarithmic function

What is H⁺ equal to in terms of pH?

H⁺ = 10^-pH

What is pH equal to in terms of H⁺?

pH = -log (H⁺) OR pH = -log (H₃O)

What are some common substances and their pHs?

Gastric juice → 2.0, pure water → 7.0, detergent → 10.0, oven cleaner → 14.0

What is a change in 1 pH unit representative of?

A 10-fold change in hydrogen concentration (small pH changes are actually huge H⁺ changes)

What is the difference between strong acids and bases/weak acids and bases?

They will act differently in terms of the donating/accepting of H⁺, however they are defined the same way

What special process can water undergo on its own?

Auto-ionization

What is the auto-ionization of water?

This is the equilibrium of water constantly interconverting according to the following reaction:

H₂O(l) ⇌ OH⁻(aq) + H⁺(aq)

What is Kw?

The equilibrium constant, specifically for the auto-ionization of water, often called the ion product constant

What is the Kw value for the auto-ionization of water?

1\.0 x 10¹⁴ (at 298 K)

What is a main difference between strong and weak acids/bases?

Their ability to conduct electricity; strong substances conduct much more effectively than weak substances

How is improved technology beneficial for science?

Advanced analytical techniques allow many concepts to be quantified, such as the strengths of different acids and bases

How is looking for trends and discrepancies integral to science?

Patterns and anomalies offer topics of further investigation and understanding, such as in the relative strengths of acids and bases tying to their molecular structure

How are the outcomes of experiments important for science?

These outcomes or models can be used as further explanation for many sorts of claims, for example that data for a particular type of reaction support that weak acids exist in equilibrium

What do strong acid and bases need for a neutralization?

A conjugate pair that is a weak acid or (and vice versa)

What two terms are interchangeable?

Ionization and dissociation

What is the difference between amphoteric and amphiprotic species?

Amphoteric species can act as both an acid and a base, whereas one type of amphoteric species, amphiprotic species, can act as proton donor or proton acceptors (teric has to do with their traits, protic has to do with their protons)

What is the conductivity of a solution dependant on?

The concentration of ions present in the solution

What does it mean if strong acids and bases are strong electrolytes?

It means they display higher conductivity than weak acids and bases

What is a neutralization?

A reaction that occurs when an acid and a base react together in which a strong acid or base is completely removed from a dissociation reaction

Is a neutralization reaction endo or exothermic?

Exothermic

Why is the enthalpy of a neutralization only the formation of H⁺ and OH⁻ ions?

Because the strong acid or base is completely dissociated, and therefore not considered

How is the enthalpy of a neutralization with a weak and strong substance different?

The enthalpy consideration in a strong substance reaction is only of hydrogen or hydroxide, however for a weak substance the endothermic ionization of the substance must be considered, meaning that weak substances will yield less exothermic reactions overall

Why is rain acidic?

Because of the dissolved CO₂ present

What is the average pH of rain water?

5\.6

What are the formations of acid deposition?

HNO₃, HNO₂, H₂SO₄, and H₂SO₃

What is one reason chemistry is important (improtont lol)?

Chemistry allows us to understand and reduce the environmental impact of human activities

What is acid deposition?

The process by which acid-forming pollutants are deposited on the Earth's surface

What is the most common form of acid deposition?

Acid rain

How does acid deposition impact the environment?

Deforestation, leaching of mineral leading to elevated acid levels, uptake of toxic materials, reduction in pH of aquatic systems, marine life intaking toxic metals, health of fish munchers, corroding of structures, and sadness

What is the pH of acid rain?

less than 5.6

What are the major pollutants causing acid deposition?

SO₂, NO, and NO₂

What are the occurrences causing acid deposition?

Volcanic eruptions, decomposition of vegetation, and highly sulphurous combustion of fossil fuels

How is acid rain formed?

The formation of nitric acid and sulfuric acid, both strong acids

How is NO formed?

N₂(g) + O₂(g) → 2NO(g)

How is NO₂ formed?

2NO(g) + O₂(g) → 2NO₂

How is HNO₃ and HNO₂ formed?

2NO₂(g) + H₂O(l) → HNO₃(aq) + HNO₂(aq)

How is HNO₃ formed?

2HNO₂(aq) + O₂(g) → 2HNO₃(g)

How is H₂SO₃ formed?

SO₂(g) + H₂(l) → H₂SO₃(aq)

How are HSO₃⁻ and H₃O⁺ formed?

H₂SO₃(aq) + H₂O(l) → HSO₃⁻(aq) + H₃O⁺(aq)

How is SO₂ formed?

S(s) + O₂(g) → SO₂(g)

How is SO₃ formed?

2SO₂ + O₂ ⇌ 2SO₃

How is H₂SO₄ formed?

SO₃(g) + H₂O(l) → H₂SO₄(aq)

What are pre-combustion methods?

These refer to methods to reduce sulphur emissions used on fuels before their combustion occurs

What are some examples of pre-combustion methods?

physical cleaning, crushing coal, removal of impurities

What are post-combustion methods?

This is used to remove dangerous materials after combustion occurs

What are some examples of post-combustion methods?

Tech that catches materials before they release into the atmosphere by other reactions