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Review

Review. What is the difference between a physical change and a chemical change?. Physical or Chemical Change?. Crumpling up a piece of paper Toast TNT exploding Recycling soda cans into new ones Flattening a penny Spilling bleach on shirt.

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Review

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  1. Review

  2. What is the difference between a physical change and a chemical change?

  3. Physical or Chemical Change? • Crumpling up a piece of paper • Toast • TNT exploding • Recycling soda cans into new ones • Flattening a penny • Spilling bleach on shirt

  4. How is this an example of the Law of Conservation of Mass?

  5. What are the reactants? • What are the products? Mercury Oxide Liquid Mercury + Oxygen

  6. Mixtures of Matter

  7. Remember… • What is a pure substance? What happens when you combine two or more substances?

  8. Mixture • a combination of two or more substances that do not chemically combine

  9. Mixtures • Each substance keeps its identity

  10. Types of Mixtures Heterogeneous Homogeneous

  11. Heterogeneous mixture • Not uniform throughout Individual substances can be seen Salad dressing

  12. Homogeneous mixture • Uniform throughout Fillings Blood

  13. Heterogeneous or Homogeneous?

  14. Heterogeneous or Homogeneous?

  15. Solutions • Aka homogenous mixtures

  16. Solutions • Solute – substance being dissolved • Solvent – the substance doing the dissolving

  17. Which is which? • Salt water is a solution of salt and water. Which is the solute and which is the solvent?

  18. Mixtures vs. Solutions • If one substance does not dissolve in another then it forms a mixture that is not a solution. Mixtures Solutions Sugar in water Sand in water

  19. Solutions aren’t just liquids – they can be found in every state GAS LIQUID SOLID

  20. Gas-gas • Air Oxygen dissolved in Nitrogen

  21. Gas-liquid • Seawater Oxygen and CO₂ dissolved in Water

  22. Liquid-gas • Breath Moist air exhaled contains water dropplets

  23. Liquid-liquid • Food coloring in water

  24. Solid-liquid • Saltwater

  25. Solid-solid • Brass solid (zinc) dissolved in a solid (copper)

  26. Alloys • Homogeneous mixtures of metals Steel – iron with carbon mixed in to increase the strength Stainless steel has other non or low-corrosive metals mixed in

  27. Alloy Examples • Bronze (copper and tin) Additives are included when the bronze needs to be more workable, harder, or easier to cast. For example, phosphorous is added to harden bronze for use in tubing and various machine parts, while lead is included to make bronze take more readily to casting

  28. Alloy Examples • Sterling Silver (silver and copper) Pure silver is too soft to be used functionally

  29. Alloy Examples • Pewter (tin, copper, lead)

  30. Some mixtures are difficult … Homogeneous? Heterogeneous?

  31. Tyndall Effect • Colloid – has larger particles that will scatter light • True solution – particles are too small to scatter light

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