Chemistry Chapter 8 Flashcards

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Questions and Answers

What is a chemical reaction?

The process by which one or more substances are changed into one or more different substances with different physical/chemical properties.

Which of the following are indications of a chemical reaction? (Select all that apply)

Color change (correct)

Production of gas (correct)

Formation of a precipitate (correct)

Evolution of energy as heat and/or light (correct)

What are the diatomic elements?

H2, N2, O2, F2, Cl2, Br2, I2

What is a chemical equation?

It represents, with symbols and formulas, the identities and relative amounts of the reactants and products in a chemical reaction. Signup and view all the answers

What are the three characteristics of a chemical equation? (Select all that apply)

Must be balanced Signup and view all the answers

What are the three steps to writing a chemical equation?

<ol> <li>Write the word equation; 2. Convert this into a formula equation with states of matter; 3. Balance the equation.</li> </ol> Signup and view all the answers

What do the following symbols represent in a chemical equation? Arrow, Down arrow, Up arrow, Delta/Triangle.

Yields Signup and view all the answers

What does it mean when we say chemical equations must satisfy the Law of Conservation of Mass?

Matter cannot be created or destroyed, so the total number of atoms must remain the same before and after the reaction. Signup and view all the answers

When do we balance an element last?

If it is in more than one compound on the same side of the equation or if it is by itself. Signup and view all the answers

How should you treat polyatomic ions when balancing a chemical equation?

As a single unit. Signup and view all the answers

When do you rewrite water as HOH (hydrogen hydroxide) when balancing an equation?

When the hydroxide ion and hydrogen are on one side of the equation and water on the other. Signup and view all the answers

If it's taking a long time to balance an equation, what should you do?

Check the formulas. Signup and view all the answers

What is a synthesis reaction?

When two or more substances combine to form a new compound. Signup and view all the answers

What are the different types of synthesis reactions? (Select all that apply)

Metal + Oxygen --> Metal Oxide Signup and view all the answers

What two synthesis reactions are good to know?

N2 + 3H2 --> 2NH3 and NH3 + H2O --> NH4OH. Signup and view all the answers

What is a decomposition reaction?

A single compound undergoes a reaction that produces two or more simpler substances. Signup and view all the answers

What are the different types of decomposition reactions? (Select all that apply)

Metal + Nonmetal --> Salt Signup and view all the answers

What is a single displacement reaction?

One element replaces a similar element in a compound. Signup and view all the answers

What are the types of single displacement reactions? (Select all that apply)

Replacement of a nonmetal by a nonmetal Signup and view all the answers

For what type of reaction do you use an activity series?

Single displacement reactions. Signup and view all the answers

What is a double displacement reaction?

Ions of two compounds exchange places in an aqueous solution to form two new compounds. Signup and view all the answers

What three products can a double displacement reaction produce?

<ol> <li>Precipitate; 2. Gas; 3. Water.</li> </ol> Signup and view all the answers

What rules are used to predict whether a double displacement reaction will produce a precipitate?

Solubility Rules. Signup and view all the answers

What is a combustion reaction?

When a hydrocarbon burns in oxygen to form carbon dioxide and water. Signup and view all the answers

What do combustion reactions release?

Light and heat. Signup and view all the answers

What is a precipitate?

A solid formed by two liquids. Signup and view all the answers

What is a coefficient in a chemical reaction?

It tells how many moles of a compound/element are in a reaction. Signup and view all the answers

What is a reversible reaction?

A chemical reaction in which the products and reactants can switch. Signup and view all the answers

What is electrolysis?

The process in which an electric current is used to produce a chemical reaction, such as the decomposition of water. Signup and view all the answers

Study Notes

Chemical Reactions

A chemical reaction transforms one or more substances into different substances with distinct physical and chemical properties, indicating a change of identity.

Indications of a Chemical Reaction

Evolution of energy as heat or light may occur.
Production of gas, evidenced by smoke or bubbles, without heat.
Formation of a precipitate, a solid generated from mixing two solutions.
Observable color change.

Diatomic Elements

Diatomic elements include H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂, forming a "7" on the periodic table.
In chemical equations, represent diatomic elements with subscripts only when alone.

Chemical Equation

Represents reactants and products using symbols and formulas, detailing their identities and relative amounts.

Characteristics of a Chemical Equation

Must accurately represent known facts, including states of matter.
Requires correct chemical formulas for all reactants and products.
Must comply with the Law of Conservation of Mass, meaning mass cannot be created or destroyed.

Steps to Write a Chemical Equation

Begin with a word equation denoting reactants and products.
Convert the word equation into a formula equation including states of matter.
Balance the equation to ensure conservation of mass.

Symbols in a Chemical Equation

An arrow signifies "yields."
A downward arrow indicates a precipitate formation.
An upward arrow denotes a gas as a product.
A delta or triangle symbolizes heat application.
Numbers above the arrow represent reaction pressure (atm) and temperature (°C).
A catalyst is denoted by additional formulas above the arrow.

Balancing Chemical Equations

Conservation of mass requires that the total number of atoms at the beginning equals those at the end of a reaction.
Balance elements last when they appear in multiple compounds or alone on one side.
Treat polyatomic ions as single units during balancing.
Rewrite water as HOH when hydroxide ions are on one side of the equation and water on the other.
Check chemical formulas for accuracy if balancing is difficult.

Types of Reactions

Synthesis Reaction: Two or more substances combine to form a new compound (e.g., A + X → AX).
Decomposition Reaction: A single compound breaks down into simpler substances (e.g., AX → A + X).

Types of Synthesis and Decomposition Reactions

Synthesis examples include metal + oxygen forming metal oxide, and nonmetal oxide + water producing acid.
Decomposition examples comprise metal carbonate yielding metal oxide and carbon dioxide.

Single Displacement Reaction

Involves one element replacing a similar element in a compound (e.g., A + BX → AX + B).
Metal replacement occurs when a metal displaces another in a compound; hydrogen can also be replaced by metals.
Nonmetal displacement occurs similarly among nonmetals.

Double Displacement Reaction

Involves ions of two compounds exchanging places to form new compounds (e.g., AX + BY → AY + BX).
Common products include precipitate, gas, or water.

Combustion Reaction

A hydrocarbon reacts with oxygen to produce carbon dioxide and water (e.g., CₓHᵧ(O𝓏) + O₂ → CO₂ + H₂O).
These reactions release significant energy as light and heat.

Other Key Concepts

A precipitate is a solid formed from the reaction of two liquids.
Coefficients indicate the number of moles present in a reaction.
Reversible reactions allow switching between reactants and products.
Electrolysis involves using electricity to drive a chemical reaction, often leading to the decomposition of compounds like water.

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Test your knowledge of chemical reactions with these flashcards from Chemistry Chapter 8. Learn key terms and their definitions, including indications of a chemical reaction. Perfect for reviewing before an exam or enhancing your understanding of the subject.