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Discover the world of substances and their interactions in chemistry. Learn about substances, mixtures, observations, chemical reactions, reactants, products, and signals of a reaction. Understand the importance of color changes, heat/light production, solid formation, and gas production as indicators of chemical reactions. Stay tuned for more exciting chapters on this educational journey!
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Investigation #1 Substances
Chemistry • Chemistry is the study of substances and their interactions.
Substance • A substance is a form of matter with a unique composition and distinct properties. --- There are millions of different substances on Earth; each is unique.
Substances can be represented with: 1. common names --- sugar 2. chemical names --- sucrose 3. chemical formulas --- C12H22O11
Mixture • A mixture is made when two or more substances are mixed together, not chemically combined. • ---- A mixture can be separated. – trail-mix is a great example. The M&M’s do NOT react with the raisins, they are just “together”.
Observations • The foundation of scientific investigation is careful and precise observation. -- Be specific with your descriptions; include as much detail as possible.
Chemical Reaction • A chemical reaction is a term used to describe a process where original substances are changed into a new substance or new substances. ---- There will always be a signal that a chemical reaction has occurred. ----- No signal, no reaction.
Chemical Reaction • The substances that go into the reaction are called the “REACTANTS”. -- This shouldn’t be difficult to remember! Reactants, well they react!
Chemical Reaction • What is produced after the reaction are called the “PRODUCTS”. -- This shouldn’t be confusing either! Products are produced!
Signals of a Reaction • There are four main signals that tell you a chemical reaction has taken place. 1. Change in color. 2. Production of heat and/or light. 3. Formation of a solid. 4. Production of a gas.
Change in Color The products end up a different color than the original reactants. -- This does not include any item that is painted or dyed. Example…. The shiny metal iron reacts with oxygen to form rust; a red-brown color.
Production of Heat and/or Light The reaction generates a change in temperature and/or produces visible light. -- Combustion is the most common example of this. Fireworks are tiny shards of metal that quickly combine with oxygen to burn; each piece is made of a different substance and burns a different color. Each is significantly “hotter” than before and you can easily view the light.
Formation of a Solid This signal is common when particular liquids are combined together. Solids form and quickly settle to the bottom of the container.
Forming of a Gas The reaction generates a gas; most often visible in the form of bubbles. -- A good example can be viewed when you add a little baking soda to vinegar. The bubbles made (Carbon dioxide gas) are a product of the chemical reaction. When the bubbling stops you have produced a gas and a new liquid; both are unique substances different from the vinegar and baking soda that you started with.
More to Come • This is just the first chapter of our adventure! Stay tuned for more! • Ask questions, seek answers, explore, and attempt to understand why things are as they are. An understanding of basic chemistry is a really cool thing! It allows you to see this world in a very different way!
