Section 2 Mixtures of Matter

Mixtures Mixture: Definition: Is a physical blend of two or more components, each of which retains its own identity and properties The formation of a mixture is due to physical change because each substance does not change its identity Example: Sand and salt

Mixtures Types of Mixtures: Heterogeneous Mixtures Homogenous Mixtures Definition: Is a mixture in which the composition is not uniform throughout the mixture Example: Salad Dressing Sand & Salt Chocolate Milk

Mixtures Homogeneous Mixture Definition: Is a mixture in which the composition is uniform throughout the mixture Homogenous mixtures are called solutions. Example: Salt and water Lemonade Steel – A mixture of Iron and carbon Is an alloy An Alloy is a homogenous mixture of metals or mixture of metals and nonmetals Gives greater strength and durability to products https://www.youtube.com/watch?v=sTrvSXJW8zw

Separating Mixtures Most matter exists naturally in the form of mixtures. To gain an understanding of matter we need to be able to separate them Mixtures are physically combined The process used to separate mixtures are based on the Physical properties of the substances that make up the mixture. Example: Mixture of Iron and sand can be separated using magnets https://www.youtube.com/watch?v=anaCLlmBSzg

Separating Mixtures Many techniques have been developed that use physical properties of substances to separate various mixtures. Filtration Separates heterogeneous mixtures composed of solids and liquids Uses a porous barrier to separate solid from liquid The liquid passes through & the solids are trapped https://www.youtube.com/watch?v=-HpRdpk1aXU

Separating Mixtures Distillation Separated homogeneous mixtures Distillation: A physical separation technique that is based on differences in the boiling points of substances Process: Mixture is heated Substance with lowest boiling point turns to vapor This liquid is then condensed into a liquid and collected https://www.youtube.com/watch?v=mP4Hgui-g6U

Separating Mixtures Crystallization Crystallization: A separation technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance. Process: Solution contains as much substance as it can possibly hold Addition of a tiny amount more will cause the dissolved substance to come out of solution. Substance with lowest boiling point turns to vapor https://www.youtube.com/watch?v=nztV4w0DtOo

Separating Mixtures Sublimation Sublimation: A process where a solid changes to vapor without melting Used when one solid sublimes but the other does not https://www.youtube.com/watch?v=jX9pskbKSw0

Separating Mixtures Chromatography Chromatography: A technique that separates the components of a mixture based on the rate that they move or based on the size of their molecules. In other words separating out a mixture of chemicals, which are in gas or liquid form, by letting them creep past another substance, which is typically a liquid or solid

Separating Mixtures Mobile phase: The moving mixture Chromatography Cont’d Mobile phase: The moving mixture Stationary phase: Substance that stays put Process: The components of the mixture moves at different rates and separate into different spots. The rate of separation depends on the different attractive forces between the paper and the components of the mixture. Paper Chromatography https://www.youtube.com/watch?v=ZCzgQXGz9Tg https://www.youtube.com/watch?v=qdmKGskCyh8 Column Chromatography https://www.youtube.com/watch?v=zAgr-6Q9mQ4

Elements Element: Is the simplest form of matter that has a unique set of properties. An element is a pure substance that cannot be separated into simpler substances by physical or chemical means Each has a unique: Name Symbol Usually two or three letters First letter is always capitalized and the remaining letters are lowercase Universally accepted by scientists Example: Iron  Fe

Compounds Is methane a pure substance? Is a pure substance made up of two or more elements that have been chemically combined in a fixed proportion Most of the matter in the universe exists as compounds Methane: CH4 is made up of the elements Carbon and Hydrogen Is methane a pure substance? Yes. Because it always has the same composition. Is methane an element? No because an element cannot be broken down into simpler substances

Separating Compounds into components  A chemical change is a change that produces matter with a different composition. Compounds are made by chemical changes. The properties of compounds are generally very different than the properties of the elements from which the compound is formed. Sodium is an extremely reactive soft metal that cannot be exposed to air or water. Chlorine is a deadly gas. The compound sodium chloride is a mostly unreactive white solid that is essential for all living things 

Separating Compounds into components Compounds can be broken into smaller components by chemical means The process of breaking down a compound into its elements is sometimes called decomposition. This often requires external energy Heat Electricity Example: Decomposition of water H20  H2 (g) + O2 (g) https://www.youtube.com/watch?v=HQ9Fhd7P_HA

Review: Classification of Matter

Chemical Changes Aka a Chemical Reaction Chemical Change: A change that involves one or more substances turning into new substances. Aka a Chemical Reaction Substance formed has different compositions and different properties from the original substance Terms: Decomposing, Rusting, Exploding, Burning, Oxidizing

Law of Conservation of Mass Definition: The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction, it is conserved. Equation: Mass reactants = Mass products

Example: What is the mass of oxygen formed in the reaction when 10 Example: What is the mass of oxygen formed in the reaction when 10.00g Mercury Oxide is converted to liquid mercury and oxygen? Reactant Products Mercury (II) Oxide Mercury + Oxygen https://www.youtube.com/watch?v=k4dIL0wPvEI

Practice: When 22. 99g of Sodium reacts with 35. 445g of chlorine Practice: When 22.99g of Sodium reacts with 35.445g of chlorine. What is the mass of sodium chloride that will form?

Practice: A 12g sample of X reacts with an unknown sample of Y Practice: A 12g sample of X reacts with an unknown sample of Y. It forms 78.9g of XY. What is the mass of Y that forms?

Practice Problems: Page 78 # 5, 6, 8 Write out the chemical equation for each

Practice Problems: Page 78 # 5 to 9 Write out the chemical equation for each

The Law of Definite Proportions A characteristic of compounds is that the elements always combine in definite proportions by mass. The Law of definite proportions states that any chemical compound will always contain a fixed ratio of elements by mass. Does not matter how large or small the sample is

The Law of Definite Proportions Example: Water (H20) Gallon of water Cup of water

The Law of Definite Proportions Review: Law of Conservation of Mass Mass Reactants = Mass Product Mass Element 1 + Mass Element 2 = Mass Compound The relative amounts of an element in a compound can be expressed as a percent by mass

Example in Book – Analysis of Sucrose Pg. 88 20g of Granulated Sugar 50g of Cane Sugar Element Analysis by Mass Percent by Mass Carbon 8.44 Hydrogen 1.30 Oxygen 10.26 Total 20.0g Law of Conservation of Mass

Practice Problems Pg. 88 #19, 20, 21

Practice Problems Pg. 88 #19, 20, 21

Practice Problems Pg. 88 #19, 20, 21

Test 1 - Next Week Tuesday 09/27/16 Includes material covered from: Chapter 1 Chapter 2 Chapter 3