Acids and Bases Overview

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Questions and Answers

What effect does increasing temperature generally have on the speed of a chemical reaction?

Decreases the speed of the reaction

Has no effect on the speed of the reaction

Reduces the frequency of molecular collisions

Triples the speed of the reaction for every 10 degrees Celsius increase (correct)

What is the primary role of a catalyst in a chemical reaction?

To increase the activation energy required

To become a reactant in the reaction

To alter the rate of the reaction without being consumed (correct)

To change the products of the reaction

How does increasing the concentration of a reactant affect a chemical reaction?

Increases the volume of the reaction mixture

Decreases the number of molecular collisions

Has no effect on reaction speed

Leads to more molecules crowded in a given volume (correct)

According to the Law of Mass Action, what influences the speed of a chemical change?

The concentration of the reacting substances Signup and view all the answers

Which statement about catalysts is true?

They can act as either accelerators or inhibitors Signup and view all the answers

What does the rate of reaction measure?

The amount of chemical change in a given time interval Signup and view all the answers

Which factor does NOT influence the speed of chemical reactions?

Size of the reaction vessel Signup and view all the answers

What is required for molecules to react according to Molecular Collision Theory?

Activation energy and correct orientation Signup and view all the answers

What is a reaction mechanism?

The stepwise sequence of reactions and the formation of intermediates Signup and view all the answers

Why do some molecular collisions not result in a chemical change?

Molecules might collide without sufficient energy or correct orientation. Signup and view all the answers

What role does temperature play in chemical reactions?

It increases the frequency of molecular collisions. Signup and view all the answers

Which of the following statements about activation energy is true?

Only some molecules will have sufficient energy to overcome it. Signup and view all the answers

What distinguishes active metals from less active metals in terms of reactivity?

Active metals combine more easily with oxygen. Signup and view all the answers

According to the Arrhenius theory, what ions do acids yield in water solutions?

H(1+) and H3O(1+) Signup and view all the answers

What does the Bronsted-Lowry theory define as a base?

A proton acceptor Signup and view all the answers

Which chemical equation demonstrates the Bronsted-Lowry theory in action?

NH3 + H2O ↔ NH4(1+) + OH(1-) Signup and view all the answers

In the Lewis theory of acids and bases, how is an acid defined?

Accepts an electron pair Signup and view all the answers

If a solution has a pH less than 7.0, what can be inferred about the concentration of hydronium ions?

[H3O+] > 1.0 x 10^7 M Signup and view all the answers

How is pH calculated according to the provided information?

pH = -log[H3O+] Signup and view all the answers

What is the sum of pH and pOH in neutral solutions?

14 Signup and view all the answers

Which statement correctly describes the relationship between pH and pOH for basic solutions?

pH > 7.0 and pOH < 7.0 Signup and view all the answers

Study Notes

Acids and Bases

Arrhenius Theory (1884):
- Acids produce H+ ions and H3O+ ions in water solutions.
- Bases produce OH- ions in water solutions.
- The theory is not applicable to non-aqueous solvents.
Brønsted-Lowry Theory (1923):
- Acids donate protons (H+).
- Bases accept protons.
- The theory is not restricted to water solutions.
- Examples:
  - HCl + H2O ⇌ Cl- + H3O+
  - NH3 + H2O ⇌ NH4+ + OH-
Lewis Theory (1923):
- Acids accept electron pairs.
- Bases donate electron pairs.
- The theory explains reactions that do not involve proton transfer.
- Coordinate covalent bonds are formed in Lewis acid-base reactions.

pH and pOH

pH = -log[H3O+]
pOH = -log[OH-]
The product of the hydronium ion concentration and hydroxide ion concentration is constant (Kw), so: pH + pOH = pKw = 14
Neutral solutions:[H3O+] = [OH-] = 1.0 x 10^-7 M, therefore pH= pOH = 7.0
Acidic solutions: [H3O+] > 1.0 x 10^-7 M, pH < 7.0, pOH > 7.0
Basic solutions: [H3O+] < 1.0 x 10^-7 M, pH > 7.0, pOH < 7.0

Chemical Kinetics

Chemical kinetics studies the mechanisms by which a chemical process reaches its final state from its initial state and the rate of the reaction.
It is the study of reaction rates and the sequence of steps involved in the reaction.

Factors Affecting Reaction Rate

Nature of the reacting substances:
- The reactivity of a substance affects the speed of its reaction.
- Active metals react quickly with acids while less active metals react slowly.
- Corrosion rates for different metals depend on their reaction rate with oxygen.
Temperature:
- Higher temperatures increase the rate of reaction because molecules move faster and collide more frequently.
- In general, reaction rate triples for every 10 degrees Celcius increase in temperature (regardless of exothermic or endothermic nature)
Catalysts:
- Catalysts alter the rate of a reaction without being used up in the process.
- Accelerators increase the reaction rate.
- Inhibitors decrease the reaction rate.
Concentration:
- Higher concentrations of reactants result in more collisions per unit time, increasing reaction rate.

Law of Mass Action

The rate of a chemical reaction is proportional to the concentration of the reacting substances.
The law explains collision theory.

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Description

Explore the fundamental theories of acids and bases, including Arrhenius, Brønsted-Lowry, and Lewis theories. Understand the calculations related to pH and pOH, and how these concepts apply to chemical reactions. This quiz covers the essential definitions and examples needed for a solid grasp of acid-base chemistry.