Introduction: Matter and Measurement

Chemistry:

The study of matter and the changes it undergoes.

Matter:

Anything that has mass and takes up space.

States of Matter

Plasma

Lightning is a plasma. Used in fluorescent light bulbs and Neon lights. Plasma is a lot like a gas, but the particles are

electrically charged.

Classification of

Matter

Pure SubstancesOnly one substance

present

MixturesPhysical

combinationof 2 or more substances

Elementscannot be broken

into simpler substances

Compoundscan be broken into

elements bychemical means

HomogeneousMixtures

One phase present

Heterogeneous Mixtures

2 or more visible phases

Substances, Compounds, Elements and Mixtures

Matter

Atoms are the building blocks of matter.

Matter

Atoms are the building blocks of matter. Each element is made of the same kind of atom.

Matter

Atoms are the building blocks of matter. Each element is made of the same kind of atom.

A compound is made of two or more different kinds of elements.

Compounds

Compounds can be broken down into more elemental particles.

Separating Mixtures:Distillation

Separates homogeneous mixture on the basis of differences in boiling point.

Separating Mixtures:Filtration

Separates solid substances from liquids and solutions.

Separating Mixtures:Chromatography

Separating Mixtures:Chromatography

Separates substances on the basis of differences in solubility in a solvent.

Classify the following substances as an element, compound or a mixture (homogeneous or

heterogeneous). Which are pure substances?

Lightly scrambled egg Water

Lava lamp Seawater

Freshly opened root beer Flat root beer

Sucrose (C12H22O11)

Properties of Matter

Physical Properties:□ Can be observed without changing a substance into

another substance. Boiling point, density, mass, volume, etc.

Chemical Properties:□ Can only be observed when a substance is changed

into another substance. Flammability, corrosiveness, reactivity with acid,

etc.

Properties of Matter

Intensive Properties:□ Independent of the amount of the substance that is present.

Density, boiling point, color, etc.

Extensive Properties:□ Dependent upon the amount of the substance present.

Mass, volume, energy, etc.

Changes of Matter

Physical Changes:□ Changes in matter that do not change the composition of a

substance. Changes of state, temperature, volume, etc.

Chemical Changes:□ Changes that result in new substances. Combustion, oxidation, decomposition, etc.

States of Matter

Chemical Reactions

In the course of a chemical reaction, the reacting substances are converted to new substances.

Chemical Reactions

Review

Identify the following as either a chemical or physical change.

Combination of sodium and chlorine to give sodium chloride. Liquefaction of gaseous nitrogen.

Separation of carbon monoxide into carbon and oxygen. Freezing of water.

Units of Measurement

SI Units

Système International d’Unités Uses a different base unit for each quantity

Units of Measurement

Mass measure of the quantity of matter in a body1 pound = 454 g

Weightmeasure of the gravitational attraction for a body

Length 1 m = 39.37 inches2.54 cm = 1 inch

Volume1 liter = 1.06 qt 1 qt = 0.946 liter

Exact vs. Inexact

Exact numbers

1 dozen = 12 items

1 gross = 144 items

Counted numbers- ex. 3 beakers Inexact Numbers Significant figures

digits believed to be correct by the person making the measurement measure a mile with a 6 inch ruler vs. surveying equipment

Accuracy -how closely measured values agree with the correct value Precision- how closely individual measurements agree with each other Scientific notation -way of signifying the significant digits in a

number

Accuracy versus Precision

Accuracy refers to the proximity of a measurement to the true value of a

quantity. Precision refers to the proximity of

several measurements to each other.

Uncertainty in MeasurementsDifferent measuring devices have different uses and different degrees of accuracy.

Significant Figures

The term significant figures refers to digits that were measured. When rounding calculated numbers, we pay attention to

significant figures so we do not overstate the accuracy of our answers.

Significant Figures

1. All nonzero digits are significant.

2. Zeroes between two significant figures are themselves significant.

3. Zeroes at the beginning of a number are never significant.

4. Zeroes at the end of a number are significant if a decimal point is written in the number.

Significant Figures

When addition or subtraction is performed, answers are rounded to the least significant decimal place.

When multiplication or division is performed, answers are rounded to the number of digits that corresponds to the least number of significant figures in any of the numbers used in the calculation.

Significant Figures - rules

multiply & divide rule - easyproduct has the smallest number of sig. fig. of multipliers

Temperature:

A measure of the average kinetic energy of the particles in a sample.

Temperature

In scientific measurements, the Celsius and Kelvin scales are most often used.

The Celsius scale is based on the properties of water.

□ 0C is the freezing point of water.□ 100C is the boiling point of water.

Temperature The Kelvin is the SI unit of

temperature. It is based on the properties of gases. There are no negative Kelvin

temperatures. K = C + 273.15

Temperature The Fahrenheit scale is not used in

scientific measurements. F = 9/5(C) + 32 C = 5/9(F − 32)

Density:

Physical property of a substance

d=mV

Dimensional Analysis

simple but important way to always get right answer way to change from one unit to another make unit factors from statements

1 ft = 12 in becomes 1 ft/12 in or 12in/1 ft

3 ft = 1 yd becomes 3ft/1yd or 1yd/3ft

Dimensional Analysis

simple but important way to always get right answer way to change from one unit to another make unit factors from statements

1 ft = 12 in becomes 1 ft/12 in or 12in/1 ft Example: Express 12.32 yards in millimeters.