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Chemical Reactions. http://sphs.spusd.net/apps/classes/show_assignment.jsp?classREC_ID =180199&showAll=true. Today’s Lesson. 20 minutes to complete test Some housekeeping Different Chemical Reactions. Housekeeping.
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Chemical Reactions http://sphs.spusd.net/apps/classes/show_assignment.jsp?classREC_ID=180199&showAll=true
Today’s Lesson • 20 minutes to complete test • Some housekeeping • Different Chemical Reactions
Housekeeping • Today – I will be handing back some of your work that has been on my desk for ages. • On Monday or Tuesday in homeroom in the morning, I will give you your portfolio with all of your marked work with comments for the year. • This will include your test and teaching toolbox. I have not marked all of the teaching toolboxes yet as I have not received them all!!
Continued • Why textbooks today? • It’s the quickest and fastest way for me to introduce these ideas to you. This will also allow me to complete these experiments later. • Our Assessment Tasks? • We will be starting an essay soon. It’s main concept will be to choose a chemical reaction of your choice.
Chemical Reactions • There are many different types of chemical reactions. These Include • Oxidation • Combustion • Reduction • Decomposition • Neutralization (acid-base) • Precipitation • Displacement
Oxidation Reaction • Oxidation occurs when a substance reacts with oxygen: • Pb (s) + O (g) PbO (s) • Some examples of oxidation includes rust and when food de-colors such as apples and butter. • Chem hint: in an equation (s) = solid, (l) = liquid, (g) = gas & (aq) = aqueous or in water
Combustion • A combustion reaction occurs when a substance burns in oxygen. • Some good examples include burning fossil fuels or wood. • Methane + Oxygen Carbon Dioxide + Water • Hydrogen + Oxygen Water
Reduction Reaction • A reduction reaction occurs when a substance loses oxygen. This normally requires a large amount of energy. • Iron Oxide + Carbon Iron + Carbon Dioxide • Reduction reactions are commonly used in the preparation of ores into a metal.
Decomposition Reactions • Decomposition occurs when a compound breaks down into simpler substances. • Not all compounds break down easily, but some can and this can be brought about through heat, light or electricity. • Silver Oxide Silver + Oxygen
Neutralization • Neutralization is the reaction between an acid and a base (alkali). They normally react to form a salt and water. • Hydrochloric Acid + Calcium Carbonate Calcium Chloride + Water + Carbon Dioxide • We will be learning more about this topic after this unit.
Precipitation • Precipitation occurs when two aqueous solutions are put together and a solid forms. • The precipitate can often be strange colors – but many are just white (yay!) • Lead Nitrate (aq) + Potassium Iodide (aq) Lead Iodide (s) + Potassium Nitrate (aq)
Displacement • A displacement reaction occurs when a more reactive element takes the place of a less reactive one in a compound. • Chromium Oxide + Aluminium Chromium + Aluminium Oxide
Questions • Answer the following questions in your workbook. • Q 1-3 on Page 176-179 • Q 2 + 3 on Page 181