An Introduction to Chemistry, Lab Skills, and Measurement Unit 1

The Scientific Method is loosely defined as the way in which a scientist goes about solving a problem. Define a Problem Evaluate the Problem Devise a Testable Hypothesis Collect Observations about the Problem Create an Experiment to test the Hypothesis Make Observations during the Experiment Draw conclusions that reflect back to the hypothesis Form a theory to explain the problem Share this theory with the Scientific Community through Peer Review Peers repeatedly test your theory If they do not agree If they do agree

A law is a concise statement of a relationship between phenomena that is always the same under the same conditions. A hypothesis is a tentative explanation for a set of observations tested modified

1. Matter is anything that occupies space and has mass. 2. A substance is a form of matter that has a definite composition and distinct properties. Chemistry is the study of matter and the changes it undergoes, as well as the study of chemical energy and its transfer water, ammonia, sucrose, gold, oxygen

A mixture is a combination of two or more substances in which the substances retain their distinct identities. 1. Homogenous mixture – composition of the mixture is the same throughout. 2. Heterogeneous mixture – composition is not uniform throughout. soft drink, milk, solder cement, iron filings in sand

Physical means can be used to separate a mixture into its pure components. magnet distillation

An element is a substance that cannot be separated into simpler substances by chemical means. 116 elements have been identified 82 elements occur naturally on Earth gold, aluminum, lead, oxygen, carbon 34 elements have been created by scientists technetium, americium, seaborgium

A compound is a substance composed of atoms of two or more elements chemically united in fixed proportions. Compounds can only be separated into their pure components (elements) by chemical means. Water (H 2 O)Glucose (C 6 H 12 O 6 ) Ammonia (NH 3 )

If homogeneous matter can be separated by physical means, then the matter is a mixture. Separating Homogenous Mixtures

Separation of Mixtures

Separating Homogenous Mixtures If homogeneous matter cannot be separated by physical means, then the matter is a pure substance. A pure substance can sometimes be decomposed into something else, the substance is then a compound.

Kinetic Nature of Matter Matter consists of atoms and molecules in motion. v SolidLiquidGas

OTHER STATES OF MATTER PLASMA — an electrically charged gas; Example: the sun or any other starPLASMA — an electrically charged gas; Example: the sun or any other star BOSE-EINSTEIN CONDENSATE — a condensate that forms near absolute zero that has superconductive properties; Example: supercooled Rb gasBOSE-EINSTEIN CONDENSATE — a condensate that forms near absolute zero that has superconductive properties; Example: supercooled Rb gas

Physical or Chemical? A physical change does not alter the composition or identity of a substance. A chemical change alters the composition or identity of the substance(s) involved. ice melting sugar dissolving in water hydrogen burns in air to form water

An extensive property of a material depends upon how much matter is is being considered. An intensive property of a material does not depend upon how much matter is is being considered. mass length volume density temperature color Extensive and Intensive Properties

Matter - anything that occupies space and has mass. mass – measure of the quantity of matter SI unit of mass is the kilogram (kg) 1 kg = 1000 g = 1 x 10 3 g weight – force that gravity exerts on an object weight = g x mass on earth, c = 9.8 m/s 2 on moon, c ~ 1.6 m/s 2 A 1 kg bar will weigh 9.8 N on earth 1.6 N on the moon

Powers of ten are used for convenience with smaller or larger units in the SI system. Units of Measurement

SI Units Units of Measurement

Volume – SI derived unit for volume is cubic meter (m 3 ) 1 cm 3 = (1 x m) 3 = 1 x m 3 1 dm 3 = (1 x m) 3 = 1 x m 3 1 L = 1000 mL = 1000 cm 3 = 1 dm 3 1 mL = 1 cm 3

Density – SI derived unit for density is kg/m 3 1 g/cm 3 = 1 g/mL = 1000 kg/m 3 density = mass volume d = m V A piece of platinum metal with a density of 22.0 g/cm 3 has a volume of 4.40 cm 3. What is its mass?

K = 0 C (°F - 32) * 5/9 = °C