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Chapter 2 science 8-2
- 1. Chapter 2 Amy Goltermann
- 2. Chapter 2.1 Matter Pure Mixture Substance Hetero- Element Compound Homogeneous geneous
- 3. Chapter 2.1 What is a pure substance? A pure substance Made up of either compounds and/or elements Has a unique set of properties Pure Can only be separated chemically Substance Can only be combined in a fixed uniform ratio Some examples of pure substances are Salt Sugar
- 4. Chapter 2.1 What is an element? An element Is a substance that cannot be broken down Has a fixed composition because it only has one type of atom Examples of elements: Oxygen Hydrogen Element Unununium
- 5. Chapter 2.1 Compound What is a compound? A compound Is a substance made from two or more simpler substances that can be separated Is always in a fixed proportion/ ratio *Note- a compound will always have two more elements that make up the composition (some of the elements combined are compounds) Some examples of compounds are Silicon dioxide Water
- 6. Chapter 2.1 What is a mixture? A mixture Mixture Can be combined in any ratio Does not have a unique set of properties This grain of Can be separated physically sand is different Some examples are Salsa Pool water Sand Than this grain of sand
- 7. Chapter 2.1 What is a heterogeneous mixture? In a heterogeneous mixture the parts are noticeably different and and each part can be taken separated easily. Salsa is a good example of a heterogeneous mixture because you can add as many jalape単o peppers but take out some of the onions (no fixed ratio). It is also a good example because it is easy to identify different ingredients and separate them.
- 8. Chapter 2.1 What is a homogeneous mixture? In a homogeneous mixture the parts are evenly distributed so it is difficult to tell the difference between two substances of the same origin. Sometimes in a homogeneous mixture, one of the parts will dissolve (like when you put sugar in water). See solutions! Pool water is a good example of a homogeneous mixture because you can take a sample from both the deep end and shallow end of the pool. The water will look the same but there will be different chemicals in each one.
- 9. Chapter 2.1 Solutions Suspensions and Colloids Liquid solutions: when a substance dissolves and becomes a homogeneous mixture Does not separate into layers Cannot be separated through a filter Light can pass through without scattering Suspensions: Separates into layers (over time) Can use a filter Light is scatters, it is cloudy and you cant see through it Colloid: Contains medium sized particles Does not separate into layers Particles spread out evenly
- 11. Chapter 2.2 What are the physical properties? There are many different physical properties to test for in a substance but the main ones are: Viscosity Conductivity Malleability Hardness Melting point Boiling Point Density
- 12. Chapter 2.2 Viscosity and Conductivity Viscosity is how resistant a substance to flowing or moving (this property is tested mainly with liquids) Honey is a good example of a liquid with a high viscosity Conductivity is how well a substance conducts heat. Often, if a substance has a high conductivity, it will be a good conductor of heat as well Most metals are good conductors of heat
- 13. Chapter 2.2 Malleability and Hardness Malleability and hardness are confusing and often confused with each other. Here are some definitions to help keep these two straight. Malleability is the ability to be hammered without shattering. Sometimes this property comes into play when shaping an object like a coin. Most metals are malleable and some substances like glass and ice are brittle Hardness can be found be testing an objects ability to be scratched. The object that scratches is harder that the scratched object (thats a lot of objects and scratches) The hardest substance known is diamond
- 14. Chapter 2.2 Melting and Boiling Point Every substance has a melting and boiling point (not when in gas form though). The melting point for water is somewhere above 0c and the boiling point is 100c. Each substance has a different melting and boiling point. To test whether a substance is pure or an alloy, you could use melting point. Melt the substance. If it all melts at the same temperature, it is a pure substance. If some of it melts but there are still some solid chunks, it is an alloy.
- 15. Chapter 2.2 Density The formula for density is: One can use density to test multiple object to see if they are the same substance or to compare multiple unknown substances Some of the uses of the physical properties are to identify or choose materials and to separate or compare substances
- 17. Separation Techniques Distillation A process that separates the substances in a solution based of boiling points. Plateau Plateau 100 90 80 70 60 50 Series1 40 30 20 10 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
- 18. Separation Techniques Distillation When there are multiple plateaus in your data (testing an unknown substance), you know that there are multiple boiling points in the substance inferring that the substance is in face a mixture Collecting these substances in the mixture separately is a piece of cake if you can identify the plateaus (use the same set up for the experiment as in the Unknown Substance lab but collect the liquid in test tube after each plateau) The buffer is the liquid in between plateaus. It is a mixture. It is what is left from the first substance to boil and the substance that hasnt boiled yet.
- 19. Separation Techniques Filtration A process that separates materials based on the size of their particles and/or solubility The technique of filtration is Funnel the same for any experiment but filters come in all shapes and sizes. Filter A common household item Paper that is also a filter is the colander Filtrate
- 20. Separation Techniques Evaporation A process used to isolate a solid dissolved in a liquid DISCLAIMER: when you use this technique, you are only going to be able to isolate the solid because the liquid will evaporate into air Example: NaCl (salt) and water Salt dissolves in water but you can use evaporation to be able to obtain the salt after it has dissolve.
- 22. Chapter 2.3 Chemical Properties When, what, where, why? Chemical properties can be observed when the substance in a sample of matter are changing into different substances.
- 23. Chapter 2.3 Flammability Flammability: a materials ability to burn in the presence of oxygen Not always desirable Laws regulating fabrics flammability (needs to be flame resistant)
- 24. Chapter 2.3 Reactivity Reactivity: how readily a substance combines chemically with other substances. Oxygen- high reactivity Iron- high reactivity Potassium- high reactivity Nitrogen- low reactivity
- 25. Chapter 2.3 Evidence of Reactivity Change in color- relation to change in time Production of gas Formation of precipitate A change in temperature
- 26. Review Questions What is the difference between a pure substance and a mixture?
- 27. Review Questions Explain the difference between a solution, a suspension and a colloid?
- 28. Review Questions Please fill in the chart:
- 29. Review Physical Properties Chemical Properties Please name three Please name three differences differences.
- 30. Review Physical Properties Chemical Properties Please name all properties Please name all properties
- 31. I hope you learned a lot about types of matter and physical properties during the presentation! Thanks for watching!