CH1: General Chemistry

The Heart of the Matter

Bring out ½ sheet of paper

Name the three states of matter (bonus of a half-point each if you can name the two others)

In outer space, would an apple have less mass?

Back on Earth, if we cut this apple into segments, what type of changes would occur? (physical or chemical?)

Problem Solving

I have a glass jar filled with a mixture of mineral oil and acetone, both of which are colorless. Oil and acetone do not mix, and thus form two layers in the jar.

Liquid A

Liquid B

Problem Solving

You want to know which of the liquids is acetone and which is mineral oil, but you can’t tell by the appearance alone. Thus, you conduct an experiment and find that:– 2.00 ml of acetone weighs 1.58 grams– 1.50 ml of mineral oil weighs 1.26 grams

What are the densities (in g/ml) of mineral oil and acetone? Based on this, which liquid floats on top?

The Heart of the Matter

MATTER – the stuff the universe is made of. It’s anything that has mass and occupies space

MASS – the amount of matter an object contains

Mass vs. Weight

Mass is constant for a given sample of matter

Weight depends on the strength of gravitational force

Will an apple have less mass in outer space?

NO

Classifications of matter

SOLID – definite volume,

definite shape

LIQUID – definite volume,

no permanent shape

GAS – no definite volume or shape

urea

chlorine

Titration setup

Atoms and molecules wiggle?

Matter moves on an atomic level – even solids.

– Solids are held in rigid structures;

their atoms vibrate– Liquid molecules slip and slide

against each other

– Motion and other forms of energy

Energy and state changes

Why does heating a substance result in state changes (e.g. ice to water to steam)?

Thermal to kinetic energy

Plasma: the fourth state of matter

So much energy, the electrons are ejected.

“ion soup”

Plasma

Examples of Plasma

Absolute Zero

-273 degrees C Outer space? Technology: less

than 1 millionth of a degree above absolute zero

Bose-Einstein condensates

BEC, briefly

Atoms occupy the same space

Atoms are indistinct from each other and form one blob

Test yourself

Steam Fluorescent light Gravel Milk Mercury (room temp)

Classifying by composition

Pure substances vs. Mixtures– Substances: fixed composition and distinct

properties (e.g. salt, water)– Mixtures: combos of 2 or more substances, each

retaining its own properties (e.g. sand, milk)

HETEROGENOUS

HOMOGENOUS

MIXTURES

COMBINATION OF TWO OR MORE SUBSTANCES IN WHICH EACH SUBSTANCE RETAINS ITS OWN CHEMICAL IDENTITY

– Homogenous– heterogenous

ALLOYS : Mixtures of metalseg. YELLOW BRASS (Cu, Zn)

STAINLESS STEEL (Fe, Cr, Ni, C) PLUMBER’S SOLDER (Pb, Sn) STERLING SILVER (Ag, Cu) GOLD ALLOYSAMALGAMS : Metal mixtures with mercuryCOLLOIDS: Intermediate dispersions or suspensions (Borderline)

COLLOIDS EVERYWHERE

ALL MATTER

Can it be separated by physical means?

PURE SUBSTANCE

HeterogeneousMixture

Homogeneous

Can it be decomposed into other substances by chemical processes?

Element Compound

Is it uniform throughout?

YES

YES

YESNO

NO

NO

Homogeneous Mixture (SOLUTION)

Classification “pachinko”

e.g. SAND

e.g. seawater

Pure Substances

ELEMENTS – cannot be decomposed into simpler substances.

Pure Substances

Elements – composed of only one type of atom Compound – composed of two or more different

types of atoms

Classification Recap

States: solid, liquid, gas, plasma, BEC Composition

– Mixtures: homogenous and heterogenous– Pure substances

Elements Compounds

Properties of Matter

PHYSICAL PROPERTIES- Measurable without changing the identity and composition of the substance

CHEMICAL PROPERTIES- Describe the way a substance may change or react to form other substances

INTENSIVE PROPERTIES-Do not depend on the amount of sample being examined.-Useful in identification Eg. Temp., Melting point, Density

EXTENSIVE PROPERTIES- Depend on the amount of sample being examined. Eg. Mass, Volume

Some Physical Properties

Temperature Color Boiling point Freezing point Hardness Density

Some chemical properties

Oxidation (rusting and tarnishing) Flammability Inertness

Changes in matter

Physical change – doesn’t entail any change in chemical composition

Chemical change – entails change in chemical structure

BOTH physical and chemical change

What type of change is this?

Next meeting

Read about atomic theory