Intro to Chemical Principles, OU, HW #1

3 substances present, 3 phases present

Hetero mixture

Assign a description with the following: heterogenous mixture, homogenous mixture, pure substance: 2 substances present, 2 phases present

Hetero mixture

Water and sand

Hetero mixture, 2 phases

Water, dissolved sugar, and undissolved sugar

Hetero mixture, 2 phases (water and dissolved sugar counts as 1 phases)

Water, Ice, and oil

Hetero mixture, 3 phases

Assign a description with the following: heterogenous mixture, homogenous mixture, pure substance with the number of phases present: water and dissolved salt

Homo mixture, 1 phase

2 substances present, 1 phase present

Homo mixute

What are the 2 general characteristics that all types of matter possesses?

All types of matter must 1) Have mass 2) Occupy space Everything in our known universe can be categorized as matter or energy. To determine the difference between matter and energy we look to see if the sample has mass and occupies space. (energy does not have mass).

Answer T/F for the following statements: All heterogenous mixtures must contain three or more substances?

False. A heterogenous mixture contains 2 or more substances. It can contain 3 but the minimum is 2.

Substances maintain their identity in a heterogenous mixture but not in a homogenous mixture.

False. Substances maintain their identity in ALL mixtures. They are physically mixed, not chemically combined. They can be seperated by physical means like evaporation.

What physical characteristics distinguishes: Gases from Liquids?

Gases have an indefinite volume. Liquids have a definite volume.

The process of melting ice

Physical change

Evaporation of water from a lake

Physical change (liquid to a gas is a change of state of matter)

Slicing a ham

Physical change (making it smaller)

Hammering a metal into a thin sheet

Physical change (making it thinner)

Melting candle wax

Physical change (solid to a liquid)

Indicate whether each statement describes a physical or chemical property?- Hemoglobin molecules have a red color

Physical property

The fact that metallic gold is solid at room temperature

Physical property

Pure substances cannot have a variable composition

True. A pure substance contains only one substance. It is a defintie composition

Pure substances are seldom encountered in the "everyday" world

True. Most substances in the "everyday" world are mixtures. There are fewer pure substances like elements by themselves. Think about food, water, skin care products- they are all mixtures.

What physical characteristics distinguishes: Liquids from solids?

Solids have a definite shape while liquids have an indefinite shape. Liquids take the shape of a container.

What physical characteristics is the same for: Gases and liquids?

Both gases and liquids have an indefinite shape. They take the shape of a container.

The process of decomposing hydrogen peroxide

Chemical change

Classify the following as a physical property, physical change, chemical property, or chemical change: The process of burning a piece of newspaper

Chemical change (KEYWORD: process)

Burning a book

Chemical change (burning initiates a chemical reaction)

Scabbing over a skin cut

Chemical change (scabbing is the result of blood clotting- chemical)

The fact that metallic copper reacts with chlorine gas

Chemical property (KEYWORD: Fact and reacts)

Indicate whether each statement describes a physical or chemical property?: Silver salt discolor the skin by reacting with skin protein.

Chemical reaction

What are 3 the aspects of matter that are of particular interest to chemists?

Chemists are particularly interested in: 1) The characteristics of matter (physical properties) 2) The composition of matter (chemical properties) 3) The transformations of matter (chemical and physical changes that occur with matter)

Indicate whether each statement describes a physical or chemical property?- Aspirin can be pulverized with a hammer.

Physical

Classify the following as physical or chemical changes: Crushing a dry leaf

Physical (making it smaller)

Classify each of the following properties of the metal magnesium as a physical property or a chemical property?- Has a density of 1.738 g/cm^3 at 20 degrees Celcius.

Physical property- density, color, melting/boiling point are all physical properties.

Classify each of the following properties of the metal magnesium as a physical property or a chemical property?- Solid at room temperature

Physical property- states of matter (solid, liquid, gas are physical properties.)

1 substance present, 2 phases present

Pure substance

What physical characteristics is the same for: Liquids and solids?

They both have a definite volume.

Classify each of the following properties of the metal magnesium as a physical property or a chemical property?- Ignites upon heating in air

This is a chemical property because it describes a reaction that occurs when Mg comes into contact with air.

Classify each of the following properties of the metal magnesium as a physical property or a chemical property?- Hydrogen gas is produced when it is dissolved in acids?

This is a chemical reaction.

Indicate whether each statement describes a physical or chemical property?- Beryllium metal vapor is extremely toxic to humans.

This statement describes a chemical property.