Substances, Mixtures, and Solubility

1. Substances, Mixtures, and Solubility

2. What is a solutionsection 1 • Substances are composed of atoms and elements • Substance is matter that has the same fixed composition, can’t be broken down by physical processes • Physical processes: boiling, changing pressure, cooling, or sorting • Chemical process: change the original substance into new substance(burning, chemical reactions, reaction to light) • REVIEW :Atom have specific protons for each element

3. Compounds • Two or more elements chemically combined in specific combinations and composition • H2O, NaCl, H2SO4, • Water, salt, sulfuric acid

4. Mixtures • Mixtures are combinations of substances that are not bonded together and can be separated by physical processes (salt water, granite, salt and pepper) • Heterogeneous Mixtures: mixture where substances are not mixed evenly • Areas have different compositions • Seeds in watermelon, minerals in granite, cereal in milk

5. Mixtures • Homogeneous mixtures: contains 2 or more substances that are evenlymixed but are not chemically bonded together Shampoo, sugar water, Kool-Aid are examples • Solutions is another name for homogeneous mixtures

6. How Solutions Form • Solutions form when a solute (salt) dissolves in a solvent (water) • Forming solids from a solution • Crystallization occurs when cooling or evaporation takes place and leaves a solid • Precipitates forms from a chemical reaction that produces a substance that isn’t soluable in solution and drops out

7. Types of Solutions(liquids solutions) • Liquid solid solutions: solid (solute) dissolves in liquid(solvent) salt in water • Liquid gas solutions: gas is dissolved in a liquid (gas dissolved in water: carbonated water) • Liquid-liquid solutions: both solute and solvent are liquids ( vinegar and water)

8. Gaseous Solution • Smaller amount of one gas (solute) is dissolved in a larger amount of gas (solvent) • Both solvent and solute are gases • Example: Our atmosphere contains 78% Nitrogen and would be the solvent and other gases in atmosphere would be the solute

9. Solid Solutions • In solid solutions, the solvent is a solid • Solute can be a gas, liquid, or solid • Solid-solid solution: alloys are mixture of 2 or more metals melted together and mixed (brass, steel)

10. Solubilitysection 2 • Water the Universal Solvent • Aqueous refers to a solution of where water is the solvent • Water can dissolve may different solutes

11. Water • Molecular Compounds: • Water is formed by sharing electrons between 2 atoms of H and 1 atom of Hydrogen • Water molecules when combined have areas of electrical charges that attract opposite charges, thus are polar charged

12. Water Molecules

13. Ionic bonds • When compounds are formed by gaining or losing electrons to bond elements together • When atoms gain and lose electrons the number of electrons change and give an overall charge on the atoms • Opposite charge atoms attract and hold each other together

14. h

15. How Water Dissolves Ionic Compounds • Because of the polar charge of water areas of water molecules attract the charged particles of ionic compounds and break them up • (Page 627 figure 8)

16. How water dissolves molecular compounds • Water molecules moves in between sugar molecules and separate them (thus dissolving) • What will dissolve? • Like dissolves like • Polar solvents dissolve polar solutes (salt and water) • Nonpolar solvents dissolves non polar solutes

17. How water dissolves molecular compounds • If you have a polar molecule and nonpolar molecule (unlike polar molecules) they will not dissolve and will not form a solution • Oil is a nonpolar molecule that will not mix with polar water, therefore these two substances will no form a solution

18. How Much will Dissolve • Solubility is a measurement of how much a solute will dissolve in a given amount of solvent • It is described as how much solvent can be dissolved in 100 ml of solvent at a certain temperature

19. How much will Dissolve • Liquid solid solutions: temperature affects how much solutes can be dissolved • Usually an increase in temperature allows more solute to be dissolved • Notice on chart that NaCl and CaCO3 become less soluble in higher temperatures

20. and c

21. How much will Dissolve • Liquid-gas solutions: increase in temperature decrease the solubility of a gas dissolved in it • Carbon dioxide is dissolved under pressure in water in pop cans • Opening a warm can of pop vrs a cold can, the gas is released much faster and leaves the solution under warmer conditions faster

22. Saturated Solutions • A saturated solutions can hold no more solute in solution at a given temperature or pressure • It will fall to bottom of solvent • A hot solution can hold more solute than at lower temperatures and when cooling the hot saturated solution a supersaturated solution may form

23. Rate of Dissolving • Rate of dissolving is sped up by: • Increasing temperature • Crushing the solute • Stirring the solution

24. Concentration • Concentration of a solution tells you how much solute is present compared to the amount of solvent • It is recorded by using percent of solute is compared to solvent • Juices concentration are written by 15%, 20% etc

25. Effects of Solute Particles • When a solute is added to water (salt water) and you want to freeze it , a lower temperature is needed (to freeze salt water could be 31℃) • If you want to boil salt water a greater temperature is needed to boil it

26. Acid and Basic Solutions • Acids: are substances that release positive H+ ions in water called a hydronium ion • When an acid mixes with water, acid dissolves and releases H+ ion

27. Properties of Acidic Solutions • Sour taste • Conduct electricity • Corrosive (break down substances) • React strongly with metals releasing H gas

28. Uses of Acids • Vinegar (acetic acid), citric acid, ascorbic acid we are familiar with • H2SO4(sulfuric acid) • Production of fertilizers, batteries, paint • HCl (hydrochloric acid) • Muratic acid used in pickling that removes impurities from the surfaces of metals, cleans motar, bricks • HNO3 (nitric acid) use in fertilizer, dyes, and plastic

29. Bases • Bases are substances that accept H+ ions and give off to a solution of water with OH- ions

30. Characteristics of Bases • Feels soapy, slippery • Taste bitter • Corrosives • Conduct electricity

31. Uses of Bases • Cleaning products • Your blood is basic in solution • NaOH (sodium Hydroxide) is known as lye and is used to make soap, clean ovens, unclog drains • CaOH (calcium hydroxide) often called lime is put on athletic fields to mark lines

32. What is pH • pH is the measure of how acidic or basic a solution is • Ranges from 0-14 where neutral pH is at 7 • Below 7 covers the range of acid solutions (closer to 0 is more acidic0 • Above 7 covers range of basic solutions (closer to 14 is more basic)

34. Strength of Acids and Bases • Some acids are helpful (HCl in stomach to digest food however too concentrated HCl will eat away on tissue • If more H+ (hydronium ions) are present the higher the acidic content (lower pH) • Bases with large amounts of OH- ions (hydroxide) have greater concentrations and are more basic (higher pH) • Each number on pH is 10 fold greater or smaller than the number before it: • Comparing ph3 to ph1 is a difference of 2 • 2 102 means that there is a difference of 100 times more acidic

35. Indicators • Indicators are compounds that react with acidic and basic solutions and produce certain colors to indicate their acidity or basicity tendencies

36. Neutralization • Neutralization is the reaction of an acid with a base • When an acid and a base are combined, they will neutralization each other and the resulting pH will be 7 • NaOH + HCl NaCl + H2O • Base acid salt water