Mixtures & Compounds

1. Mixtures & Compounds

2. Matter Heterogeneous mixture Homogenous Mixture NO Uniform Distribution? YES Fixed Composition ? YesNo Pure substance solution Can it be broken down into simpler substances? Element compound

3. Pure Substances • Has a fixed, uniform compositionand properties Can be an element or a compound.

4. Atoms & Elements • Elements: A substance that cannot be broken down into simple substances. An atom is the smallest particle of an element. An element has a fixed composition because it contains only one type of atom. • Atoms: basic building block of matter. Unique physical and chemical properties determined by the number or protons. • Examples are nitrogen and oxygen the two main gases you breathe.

5. Compounds • Made from two or more simpler substances. • Can be broken down to simpler substances by chemical reactions (burning, reacting with chemicals, reacting with light) • Properties differ from those substances that make them. Example O and H are gases at room temperature, but water is a liquid. • Contains 2 or more elements joined in a fixed proportion /ratio. • H₂O water • CO₂ carbon dioxide • Na Cl sodium chloride

6. Mixtures • Retain some of the properties of their individual substances. • Properties of a mixture can vary because the composition of a mixture is not fixed. The type of pepper and quantity used determines hotness. • May or may not be evenly distributed : homogenous and heterogeneous

7. Homogenous • The substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another. • Based on the size of its largest particles, a mixture can be classified as a solution, a suspension, or a colloid.

8. Heterogeneous • Means different and kind • Particles are noticeably different from one another.

9. Suspension • A heterogeneous mixture that separates into layers over time. (pepper and water) • Particles are not evenly mixed and can be easily separated by settling or filtration • Can’t scatter light. • Muddy water

10. Colloids • Contains particles that are intermediate in size between the small particles in solution and the larger particles in a suspension • Doesn’t separate into layers and can’t use filter paper to separate particles • Can scatter light • Examples: milk, fog (water droplets in air),gelatin, mayonnaise, shaving cream, whipped cream

12. Solutions • When substances dissolve and forms a homogenous mixture, the mixture that forms is called a solution. (salt + water) • The particles are too small to settle out of the solution, be trapped by a filter, or scatter light. • Can separate by boiling and evaporating

13. Parts of a solution • Solvent:Largest amount, dissolves other substance • Solute:Smaller amount, is dissolved • Water is a “universal solvent” and is part of many solutions. In many living organisms nutrients are dissolved in water. It is an important part of blood, saliva, tears. For trees water is a part of sap which carries sugar to the cells.

14. Common Solutions

15. Solubility • Solubility: a measure of how well a solute can dissolve in a solvent at a given temperature. Can be used as a property • Saturated: no more sugar dissolves into tea, as much solute as possible is dissolved in a given temperature • Unsaturated: doesn’t hold as much of a solute as is possible at a given temperature

16. Changing Solubility • 1. Temperature: Most substances in crease when temperature is increased except gases • 2. Pressure: Gases become more soluble with increased pressure • 3. Like dissolves like: polar and non polar don’t mix

17. Concentration • Concentration : the amount of solute dissolved in a solvent. • Dilute: Little solute • Concentrated :more solute

18. Effects of solutes • 1. solutes can decrease the F.P. of solvent • 2. solutes can increase the B.P. of solvent • Car antifreeze: acts to decrease the F.P to – 13 C and Increase B.P. to 176 C • Adding salt to water increases the boiling point. • Adding salt to ice decreases the freezing point

19. Solids from Solutions • Crystallization: Solute comes back out of solution to form a solid by cooling or evaporating. • Some are chemical reactions and form a precipitate. In a shower or sink minerals interact with the water and soap leaving soap scum. • In caves water can interact with limestone to form stalactites and stalagmites.

20. Acids • Sour taste • Common examples: lemons, limes, citrus, vinegar, tea, tomatoes, green leafy vegetables ( folic acid), fertilizer ( nitric acid and phosphoric acid), car battery ( sulfuric acid), lactic acid from exercise • Reacts with metals (Mg, Zn, and Fe) and is corrosive and carbonates (forms a gas) limestone • Turns Blue litmus paper Red

21. Acids & Bases in Digestion • Mouth PH is 7 contains amylase which breaks down carbohydrates to simple sugars • Stomach contains HCL which has a PH of 2 the enzyme pepsin breaks down proteins to amino acids and works best with acids • Small Intestine contains Bicarbonate ion which is basic and has a PH of 8 , other enzymes break down Carbohydrates, fates, and proteins which works best in a basic environment.

22. Bases • Bitter taste • Slippery • Common examples: drain cleaners, glass cleaners, ammonia, MOM, calcium carbonate, baking soda, soap, shampoo, detergent • Turns red litmus paper Blue

23. PH Scale • Tells if the substance is an acid or base • 0-14 • Low PH = High Hydrogen ions Acidic • High PH = Low Hydrogen ions Basic • Limes = 1.8 Bananas = 4.5 • Milk = 6.3 Eggs = 7.1

24. Acid Rain • It is normal to have some acid in rain and a PH about 5.5. Some places the acid rain can have a PH as low as 3.0. The acid is from Nitrogen oxide and Sulfur Oxide. This acidic rain can damage statues, buildings, forests and kill fish

25. Acid & Base Reaction • Neutralization can occur with the correct concentration of acid and base. It forms salts and water.