How do Chemical Reactions Affect Our Daily Lives?

“Practical Applications” Have a use that people consider important, handy or helpful

Group Activity Groups of 3 Writer, task manager, time watcher Come up with a definition of chemical reaction Discuss photos on page 110 and 111. Explain why each involves a chemical reaction List 3 more chemical reactions you consider to have practical applications List 3 chemical reactions you consider NOT to have practical applications

Chemical Reactions with practical applications Chemical reactions that have a use that people consider important, handy or helpful e.g. Burning wood is useful for creating heat for a home e.g. the millions of chemical reactions occurring in our bodies that take food and turn it into energy that helps run our bodies and helps us grow.

Chemical Reactions that are NOT practical Chemical reactions that are not helpful or handy and may even be a nuisance. e.g. rusting, corrosion, rotting, condensation build up

Summarizing Group activity Car Battery: chemicals react to produce electricity to run a vehicle Welder: chemical reaction which allows one to mend together two pieces of metal, creating a strong bond between both pieces

Summarizing Group activity cont… Flare: a chemical reaction that burns for a long period of time, allowing one to use the light and smoke to signal for help Food preservatives: chemical reaction with the food which helps keep food fresh for longer periods of time

Summarizing Group activity cont… Fresh-baked bread: chemicals (yeast) in the bread dough react to create a nice fluffy, tasty loaf instead of a flat hard chewy one. Food cooking: the fuel burned allows one to cook food to make it tasty.

Summarizing Group activity cont… Ethanol added to gasoline: creates a fuel that allows a vehicle to burn cleaner and put lest pollutants in the air. Bleach: useful in disinfecting things and brightening fabrics

Chemical Reactions in Our Lives Chemical Reaction: A change in matter that produces one or more new substances with new properties

Physical and Chemical Properties physical property: a description of how a substance looks. No new substance is formed. Requires you to use your five senses to observe. e.g. colour, texture, density, odor, solubility, taste, hardness, magnetism, luster, malleability. chemical property: a description of the changes a substance can undergo to form one or more new substance(s) e.g. Reaction with an acid or base, flammability, bleaching ability, corrosion, rust, production of a gas, reactivity. https://www.youtube.com/watch?v=oF0lN0jZYx0

Physical and Chemical Changes physical changes: does not produce a new substance and can sometimes be easily reversed. e.g. changes of state (melting, evaporating, condensation, sublimation and dissolving). Dissolving sugar in water can be reversed by evaporating the water off Cutting a log in half cannot be reversed

Physical and Chemical Changes Continued chemical change: change a substance undergoes which produces one or more new substances. Is usually difficult to reverse. e.g. new colour appears, a solid or precipitate appears, heat/light is absorbed or produced, bubbles are formed, forest fires, rusting of a vehicle, rotting of banana are impossible to reverse A rechargeable battery can be reversed

Physical or Chemical Change…That is the Question! a. perfume evaporating on your skin b. butter melting c. wood rotting d. autumn leaves changing color e. burning sugar f. mixing sugar in water g. digesting food h. freezing water to make ice cubes i. burning gasoline in a lawnmower j. tearing a piece of aluminum foil k. grating cheese l. fermenting of cheese

Physical or Chemical Change…That is the Question! a. boil b. burn (combustion) c. condense d. corrode e. crumple f. ferment g. melt h. rust i. crush j. freeze k. oxidize l. tarnish m. explode n. grind o. rot p. vaporize q. photosynthesis r. sublimation

What Makes up a Chemical Reaction? Reactants: substances that react together in a chemical reaction Products: new substances produced in a chemical reaction Reactants Products

Important Reactions photosynthesis carbon dioxide + water + sun → sugar + oxygen 𝐶𝑂 2 + 𝐻 2 𝑂+𝑒𝑛𝑒𝑟𝑔𝑦 → 𝐶 6 𝐻 12 𝑂 6 + 𝑂 2 cellular respiration sugar + oxygen+ energy → carbon dioxide + water 𝐶 6 𝐻 12 𝑂 6 + 𝑂 2 → 𝐶𝑂 2 + 𝐻 2 𝑂+𝑒𝑛𝑒𝑟𝑔𝑦