Introduction to Chemistry Ms. Argenzio

What is Chemistry? Chemistry: The study of the composition and structure of matter, the properties of matter, and the energy involved in changing matter.

Matter: anything that has mass takes up space (volume) What is matter? Matter: anything that has mass takes up space (volume) Homogeneous: matter which has a uniform composition throughout Heterogeneous: matter which has a non-uniform composition throughout

Definitions Composition: what type of atoms/molecules make up a sample of matter Structure: how the atoms are arranged in a sample of matter Properties: physical (descriptive) & chemical (behavioral) characteristics of matter

Properties Extensive Properties: -depend upon amount -examples include mass and volume Intensive Properties: do not depend upon amount -examples include density, melting point, boiling point

Structure of Matter Pure Substances: A specific type of matter with its own composition, structure, and properties Includes both elements and compounds Elements: Simplest building blocks of matter Composed of only one type of atom Cannot be broken down by ordinary chemical change

Compounds: Two or more elements chemically combined in a constant(fixed) ratio by mass Usually composed of molecules or ions Can be decomposed chemically

Two or more substances physically combined Mixtures Mixtures: Two or more substances physically combined Composed of more than one type of particle Ratios by mass may vary

Law of Conservation of Matter: Atoms can not be created nor destroyed during chemical or physical changes. The atoms are just rearranged. (The total number and type of atoms in the universe is constant)

LAW OF CONSERVATION OF MATTER QUESTIONS 1) Given the following reaction 2Na(l) + Cl2(g) 2NaCl (l) a) Identify the reactant(s)___________________________ b) Identify the product(s)___________________________ c) A 460. gram sample of Na(l) reacts with a 710.g sample of Cl2(g). What is the total mass of NaCl(l) produced.

2) Given the following reaction Example 2 2) Given the following reaction 2NaHCO3 (s) + heat Na2CO3(s) + H2O(g) + CO2 (g) Determine the total mass of sodium carbonate produced if 3360. kilograms of NaHCO3 reacts completely to produce 360. kilograms of H2O and 880. kilograms of CO2?

Problem 3 3) In an experiment, 2.54 grams of copper completely reacts with sulfur, producing 3.18 grams of copper(I)sulfide. Determine the total mass of sulfur consumed.

Changes Chemical Changes: Involves the rearrangement of the particles of matter to produce a new substance of new chemical composition. Signs of a chemical change (chemical reaction) include Color/Odor change Production of gas/solid product Energy (Heat/Light) Not easily reversed

Physical Changes: Changes the appearance of the sample of matter but not its identity (composition). Examples include changes in size, shape or phase.

Density Density – mass per unit of volume Formula on Table T in reference tables Density = Mass Volume Element densities can be found on Table S

Example 1 What is the density of a 2cm x 3cm x 4cm aluminum block with a mass of 64.8g?

What is the volume (in cubic centimeters) of a 10.0g block of gold? Example 2 What is the volume (in cubic centimeters) of a 10.0g block of gold?

Separating Mixtures

...how could you separate this mixture? Separating Mixtures Mixing sulphur and iron... ...how could you separate this mixture?

Separating Mixtures

Do not put magnetic directly on iron Hold the magnet below the Petri dish Sulphur + Iron mixture Petri dish Magnet

Separating Mixtures: Filtration – separating an insoluble solid from a solution filter paper Mixture (salt, sand, water) filter funnel Mixture (salt and water)

Separating Mixtures: Evaporation – separating a soluble solid from a solution Water Evaporating dish Mixture (salt and water) Bunsen burner

Separating Mixtures: Distillation – separating 2 soluble substances based on boiling points What is happening here? Water Vapour Mixture (salt and water) Bunsen burner Water

Separating Mixtures You’re stranded on a desert island surrounded by sea water, sadly your science teacher is lost at sea but luckily all your science equipment has washed up... ...how could you separate a mixture of sand, salt and water to get drinking water?

Goal: to extract clean fresh water Come up with a plan, you will need: A list of equipment A series of steps You should be able to explain your reasoning for each step, use your science knowledge!