Chemistry Chapter on Chemical Reactions

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Questions and Answers

What evidence can indicate that a chemical reaction has occurred?

Evaporation of a liquid

Freezing of a substance

Change in air pressure

Color change (correct)

What is the main difference between a word equation and a skeleton equation?

Word equations lack details about the number of atoms involved. (correct)

Skeleton equations include the products only.

Word equations represent chemical formulas.

Skeleton equations show reactants but not products.

Which process is an example of a physical change rather than a chemical change?

Burning wood

Rusting iron

Rotting food

Boiling water (correct)

In a balanced chemical equation, what does the coefficient represent?

The number of molecules or atoms involved Signup and view all the answers

Which of the following equations uses chemical formulas to convey information about reactants and products?

Al(s) + Br(l) → AlBr3(s) Signup and view all the answers

What do gas bubbles produced during a reaction typically indicate?

Formation of a new compound Signup and view all the answers

Which step must be taken after adjusting coefficients in a chemical equation?

Ensure the coefficients are in their lowest possible ratio Signup and view all the answers

What is one reason why chemical equations must be balanced?

To demonstrate that atoms are conserved Signup and view all the answers

What occurs to particles during a chemical change?

They rearrange to form new substances. Signup and view all the answers

Which characteristic best describes substances in a solid state?

They vibrate in position and have a definite shape. Signup and view all the answers

Which factor does NOT influence Brownian motion?

Density of the material. Signup and view all the answers

How is a molecular formula different from an empirical formula?

It shows the exact number of atoms in a molecule. Signup and view all the answers

Which of the following is a sign of a chemical reaction?

Formation of a gas from liquid. Signup and view all the answers

What is Brownian motion primarily the result of?

Collisions with surrounding fluid molecules. Signup and view all the answers

Which of the following statements is true regarding reactants and products?

Reactants are substances that undergo change. Signup and view all the answers

What effect does increasing temperature have on Brownian motion?

It increases the kinetic energy of fluid molecules. Signup and view all the answers

Study Notes

Evidence of a Chemical Reaction

Temperature change can indicate a chemical reaction.
Many reactions release energy as heat and light.
Other reactions absorb heat.
Color change can indicate a chemical reaction.
Odor, gas bubbles, and the formation of a solid are also indicators of chemical change.

Representing Chemical Reactions

Equations are used to represent chemical reactions.
They show the reactants (starting substances) and products (substances formed).

Word Equations

Express reactants and products in words.
They lack information about the number of atoms involved.

Skeleton Equations

Show symbols and formulas for reactants and products.
They also lack information about the number of atoms involved.

Chemical Equations

Use chemical formulas to show the identities and relative amounts of the substances involved in a chemical reaction.

Balancing Chemical Equations

A coefficient is the number written in front of a reactant or product.
Balancing ensures the Law of Conservation of Mass is obeyed.

Steps for Balancing Equations

Write the skeleton equation for the reaction.
Count the atoms of each element in the reactants.
Count the atoms of each element in the products.
Change the coefficients to make the number of each element equal on both sides of the equation. This shows that atoms are conserved.
Write the coefficients in their lowest possible ratio.
Check your work.

Chemical Reactions

The process by which the atoms of one or more substances are rearranged to form different substances is called a chemical reaction.
Another name for a chemical reaction is a chemical change.

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Description

This quiz covers key concepts related to evidence and representation of chemical reactions. It discusses indicators of chemical changes, including temperature and color changes, and explains different types of equations used to represent these reactions. Test your understanding of balancing chemical equations and terminology.