CH 1000 MOD 1 REVIEW HW

CH1000 Fundament als of Chemistry Module 1 – Chapter 4

Properties of Substances

• Each substance has a set of properties that are characteristic and give it a unique identity.

• Properties are classified as either physical or chemical

• Physical properties are inherent characteristics that can be determined without altering the composition.

• Chemical properties describe the ability of a substance to either undergo a reaction with another substance or to decompose.

• No two substances have identical physical and chemical properties.

Physical Changes

•Physical changes are changes in physical properties (such as size and density) or changes in states of matter without a change in composition.

•No new substances are formed during a physical change!

•Sawing wood is a physical change – the wood changes shape, but the resulting pieces are still wood!

•Burning wood is a chemical change resulting in the release of energy in the form of heat and light

Chemical Changes

•In a chemical change, new substances are formed that have different properties and composition from the original material.

•For example, when copper metal (Cu) is heated in air, the shiny metal turns black as copper(II) oxide is formed on the surface.

Chemical Equations

•A chemical equation is used to represent a chemical change

•Reactants are on the left hand side of the equation. They are the starting substances of a reaction.

•Products are on the right hand side of the equation. They are the substances produced in the chemical reaction.

Reactants Products

Energy

• Energy is the capacity of matter to do work. • Types of energy include mechanical, chemical, electrical and nuclear.

• Potential energy (PE) is stored energy, the energy an object possesses due to its position. • Water backed up behind a dam

• Kinetic energy (KE) is energy that matter possesses due to its motion. • When the water backed up behind a dam is released, the PE converts to KE in motion which

can be used to produce electricity.

• Law of Conservation of Energy: Energy cannot be created or destroyed, only transformed from one form to another.

• In chemistry, energy is most frequently released as heat.

Heat: Quantitative

Measurement

•The SI unit for energy is the joule (J).

•The specific heat of a substance is the amount of heat (gained or lost) required to change the temperature of 1 g of the material by 1 °C.

•The specific heat of water is much higher than most substances.

Specific Heat Capacity

•When an object is heated or cooled, the amount of energy transferred depends on three things: • The amount of material • The magnitude of the

temperature change

• The identity of the material gaining or losing energy

Reading Review

WHAT IS THE DIFFERENCE BETWEEN PHYSICAL AND CHEMICAL PROPERTIES?

WHAT IS THE DIFFERENCE BETWEEN PHYSICAL AND

CHEMICAL CHANGES?

WHAT IS THE DIFFERENCE BETWEEN POTENTIAL AND

KINETIC ENERGY?

WHAT IS THE LAW OF CONSERVATION OF

ENERGY?

WHAT IS THE DIFFERENCE BETWEEN SPECIFIC HEAT

AND HEAT?