Chemistry: Catalysts and Reaction Energy

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Questions and Answers

Which term describes a mixture that does not have a uniform composition and in which the individual substances remain distinct?

Homogeneous mixture

Colloids

Heterogeneous mixture (correct)

Solutions

What are coffee and corn starch with water examples of?

Colloids (correct)

Heterogeneous mixture

Homogeneous mixture

Solutions

Which of the following is a suspension?

Milk

Muddy water (correct)

Smoke

Fog

What is the jerky random movement of particles in a liquid colloid due to particle collisions known as?

Brownian motion (C) Signup and view all the answers

Two liquids that separate shortly after being mixed are said to be:

Immiscible (A) Signup and view all the answers

What forms can energy be transformed into according to the Law of Conservation of Energy?

Chemical and Thermal (A) Signup and view all the answers

Which of the following is NOT a type of energy described in the content?

Joule (D) Signup and view all the answers

Which option correctly describes 'Specific Heat'?

The thermal energy required to change one gram of a substance by one degree Celsius (B) Signup and view all the answers

What is the function of energy that is transferred between substances at different temperatures?

Heat (B) Signup and view all the answers

What unit is most commonly associated with measuring the amount of energy in the SI system?

Joule (D) Signup and view all the answers

Which of the following describes a homogeneous catalyst?

A catalyst that exists in the same phase as the reactants (C) Signup and view all the answers

What does the collision theory explain?

That molecules must collide with the correct orientation and sufficient energy for a reaction (A) Signup and view all the answers

What is the term for a catalyst in a different phase from the reactants?

Heterogeneous catalyst (B) Signup and view all the answers

Which factor measures the amount of a substance in a given volume?

Concentration (A) Signup and view all the answers

Which statement is true about catalyzed reactions?

Catalysts lower the activation energy needed for the reaction. (B) Signup and view all the answers

What expresses concentration in terms of the number of moles of solvent per liter of solution?

Molality (C) Signup and view all the answers

Which of these has units of mol/kg?

Molality (D) Signup and view all the answers

Which term correctly classifies a tossed salad or taco?

Heterogeneous mixture (B) Signup and view all the answers

Which scatters a beam of light as it passes through?

Heterogeneous mixture (C) Signup and view all the answers

Which is not a heterogeneous substance?

Soft drink (D) Signup and view all the answers

What term refers to the presence of a particular amount of substance in a system?

Concentration (B) Signup and view all the answers

Which term describes the speed at which chemical reactions occur?

Reaction Rate (A) Signup and view all the answers

What is the minimum energy needed for a chemical reaction to take place?

Activation Energy (B) Signup and view all the answers

Which factor affects reaction rate by changing the number of collisions between particles?

Surface Area (A) Signup and view all the answers

What is known as a substance that speeds up a reaction without being consumed?

Catalyst (B) Signup and view all the answers

What do we call a substance that slows down the rate of a chemical reaction?

Inhibitor (C) Signup and view all the answers

What is the function of the thermometer in the calorimeter?

To measure the temperature (A) Signup and view all the answers

Which part of the calorimeter is responsible for mixing the water?

Stirrer (B) Signup and view all the answers

What is the main purpose of the insulated container in a calorimeter?

To prevent heat exchange with the surroundings (C) Signup and view all the answers

Which component in the calorimeter is directly ignited to start the reaction?

Sample (A) Signup and view all the answers

What role do the ignition wires play in a calorimeter?

Igniting the sample (A) Signup and view all the answers

What term refers to the amount of substance present in a given volume?

Concentration (C) Signup and view all the answers

Which equation expresses the relationship between the rate of a reaction and the concentrations of reactants?

Rate Law (C) Signup and view all the answers

The numerical constant value in the rate law equation is known as the:

Specific Rate Constant (A) Signup and view all the answers

What term refers to how the rate is affected, in the rate law equation for a reaction?

Reaction Order (A) Signup and view all the answers

Which experimental technique involves measuring the rate of a reaction at the beginning, before significant product formation occurs?

Method of Initial Rates (B) Signup and view all the answers

The rate of a reaction at a specific point in time is referred to as the:

Instantaneous Rate (D) Signup and view all the answers

What is a complex reaction involving multiple elementary steps termed?

Reaction mechanism (B) Signup and view all the answers

What is the sequence of individual chemical reactions that occur to bring about the overall reaction called?

Reaction mechanism (B) Signup and view all the answers

What is an unstable species formed in one step of a multi-step reaction and consumed in another step called?

Intermediate (D) Signup and view all the answers

What changes with temperature in a reaction?

Rate constant (D) Signup and view all the answers

What is the method of initial rates used to determine?

The rate law of a reaction (C) Signup and view all the answers

Which of the following is a property of weak acids?

Partially dissociate in water (D) Signup and view all the answers

What is the concept of a pH scale used to measure?

Concentration of hydrogen ions in a solution (C) Signup and view all the answers

A substance that can act as both an acid and a base is called?

Amphoteric (B) Signup and view all the answers

Which concept extends the definition of acids and bases beyond aqueous solutions?

Bronsted-Lowry model (A) Signup and view all the answers

Which property describes a solution with a pOH less than 7?

Acidic solution (B) Signup and view all the answers

What is the pH range for an acidic solution?

Less than 7 (B) Signup and view all the answers

Which concept explains substances that can change from acids to bases and vice versa by gaining or losing protons?

Bronsted-Lowry theory (D) Signup and view all the answers

What is a substance called that increases the concentration of hydrogen ions (H⁺) in aqueous solution according to the Arrhenius model?

Acid (B) Signup and view all the answers

Which model defines a base as a substance that donates a hydroxide ion?

Arrhenius model (D) Signup and view all the answers

What does a substance become when it accepts a proton?

Conjugate acid (A) Signup and view all the answers

What is a measure of the amount of solute in a given amount of solvent or solution?

Concentration (D) Signup and view all the answers

What effect describes the scattering of light as it passes through a colloid?

Tyndall effect (C) Signup and view all the answers

Which type of mixture has particles that settle out over time?

Suspension (D) Signup and view all the answers

What term refers to the process in which particles of one substance are distributed uniformly throughout another substance?

Solution (C) Signup and view all the answers

What term describes when a solute can no longer dissolve in a solvent at a given temperature and pressure?

Saturation (C) Signup and view all the answers

Study Notes

Chemistry Study Notes

Types of Mixtures

A heterogeneous mixture is a mixture that does not have a uniform composition and in which the individual substances remain distinct.
Examples of heterogeneous mixtures include coffee and corn starch with water.
A suspension is a heterogeneous mixture, such as muddy water.

Energy and Work

Energy is the capacity to do work or produce heat.
The Law of Conservation of Energy states that energy cannot be created or destroyed, only transformed from one form to another.
Chemical potential energy is the energy stored in the bonds of chemical compounds.
Heat is the transfer of thermal energy between two bodies due to a temperature difference.
The unit commonly used to measure energy in the International System of Units (SI) is the Joule.
Specific heat is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius.

Concentration and Reaction Rates

Concentration refers to the amount of substance present in a system.
Reaction rate is the speed at which a chemical reaction takes place.
Activation energy is the minimum amount of energy required for a chemical reaction to occur.
Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process.
Surface area affects the rate of a reaction by influencing the number of collisions between reacting particles.
Molality is a measure of concentration that expresses the number of moles of solvent per liter of solution.

Catalysts

Homogeneous catalysts exist in the same phase as the reactants.
Heterogeneous catalysts exist in a different phase from the reactants.

Calorimeter

A calorimeter is a device used to measure the heat of a reaction.
The parts of a calorimeter include a thermometer, ignition wires, stirrer, oxygen, insulated container, and water.

Reaction Mechanisms

A reaction mechanism is the sequence of individual chemical reactions that occur to bring about the overall reaction.
An intermediate is an unstable species formed in one step of a multi-step reaction and consumed in another step.
The rate constant of a reaction changes with temperature.
The specific rate constant (k) is a measure of reaction order.
The method of initial rates is used to determine the rate law of a reaction.

Acids and Bases

An amphoteric substance is one that can act as both an acid and a base.
The Bronsted-Lowry model extends the concept of acids and bases to substances other than water.
pH measures the concentration of hydrogen ions in a solution.
Weak acids partially dissociate in water.
A basic solution has a pOH greater than 7, while an acidic solution has a pOH less than 7.
pOH is the negative logarithm of the hydroxide ion concentration in a solution.

Solvation Process

Solvation refers to the process of solvent particles surrounding solute particles to form a solution.

Factors Affecting Solvation

Lowering the temperature can decrease the rate of solvation.

Supersaturated Solution

A supersaturated solution is made by heating to high temperature, saturating, and then slowly cooling.

Energy Change During Solution Formation

The process of energy change that occurs during solution formation is known as the heat of solution.

Solute Properties

Solubility is the property of a solute that describes its ability to dissolve in a solvent.

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Description

Test your knowledge of catalysts, reaction energy, and collision theory with these multiple-choice questions and diagram labeling exercises. Learn about the differences between homogeneous and heterogeneous catalysts and how they affect reaction energy.