Modeling Chemical Reactions

Flashcards based on key concepts in modeling chemical reactions.

What is a physical change?

A physical change alters a material without changing its chemical composition.

What happens during a chemical change?

The material changes into new substances with new compositions.

What signifies a chemical equation?

A chemical equation represents a chemical reaction.

List the six signs of a chemical change.

Color change, temperature change, producing a gas, producing a solid/precipitate, making light, making electricity.

What is a precipitate?

A solid that forms from a chemical reaction.

What must a properly written chemical equation represent?

Known facts, correct formulas, and satisfy the law of conservation of mass.

What does the law of conservation of mass state?

Mass cannot be created nor destroyed, only transferred.

What is the difference between a coefficient and a subscript?

A coefficient applies to all elements in a formula, while a subscript applies only to what is directly in front of it.

What is bond energy?

The energy difference between bonded and unbonded elements.

What type of reaction occurs in which one compound breaks down into two or more products?

Decomposition reaction.

What reaction type involves two substances combining to form one?

Combination reaction.

What defines a combustion reaction?

It is a chemical change where a substance reacts with oxygen, often producing energy.

What are the three requirements for writing a balanced chemical equation?

Represent known facts, use correct formulas, satisfy the law of conservation of mass.

What is the role of a catalyst in a reaction?

To speed up a reaction by lowering the activation energy.

What is kinetic energy's role in reaction rates?

Increased kinetic energy results in more collisions, increasing the reaction rate.

How do temperature changes affect reaction rates?

As temperature increases, both the number and energy of collisions increase, raising the reaction rate.

What occurs during a single-replacement reaction?

One element replaces another element in a compound.

What is a double-replacement reaction characterized by?

Two reactive compounds exchange positive ions, forming two new compounds.

In what situation does a precipitate form?

When one or more products in a double replacement reaction are insoluble.

What is soluble in water?

An ionic compound that dissociates into ions in water.

What is an insoluble ionic compound?

An ionic compound that does not dissociate in water, remaining intact.

What does it mean if a compound is slightly soluble?

It may or may not dissolve in water under lab conditions.

How can you tell if a reaction occurs in a double-replacement process?

If one product is insoluble and forms a solid/precipitate.

What is required for a chemical reaction to take place according to the collision theory?

Particles must collide with sufficient energy.

What do subscripts in a chemical formula indicate?

The number of atoms or ions in a particular compound.

How is the reaction rate affected by concentration?

Increasing concentration increases the number of collisions, thus increasing the reaction rate.

What type of reaction is characterized by the release of energy in the form of heat and light?

A combustion reaction.

What are the common products of a combustion reaction involving hydrocarbons?

Carbon dioxide and water.