When the atoms of one or more substances are rearranged to form different substances. CH 4 + 2O 2 ⇒ CO 2 + 2H 2 O Reactants: Starting substances Products: Ending Substances
+Separates two or more reactants or products ⇒Separates reactants from products ↔Separates reactants from products and indicates a reversible reaction (s)Identifies a solid state (l)Identifies a liquid state (g)Identifies a gaseous state (aq)Identifies a water solution (Aqueous)
Mass is neither created nor destroyed during a chemical reaction
1. Energy change 2. Color change 3. Odor change 4. Production of gas 5. Formation of a solid (precipitate)
Energy either being gained or released as heat or light Two types: ◦ Exothermic: Energy released by the reaction We will see light or feel heat ◦ Endothermic: Energy gained by the reaction We will feel the reaction getting cold
Typically associated with another sign of a chemical change ◦ Mixing of colors, diluting, etc, are not signs of a chemical change
Formation of bubbles, etc ◦ This is not caused by heating or boiling a substance.
A solid is formed during the reaction, when adding or taking away energy from the rxn. This solid is known as a precipitate. It is NOT mean the freezing of a liquid into a solid.
Chemical Rxn in word format: Solid Aluminum and liquid bromine react to produce solid aluminum bromide.
Chemical reactions using chemical symbols and an arrow. Al(s) + Br 2 (l) AlBr 2 (s)
They are two different ways to write the same thing. Solid Aluminum and liquid bromine react to produce solid aluminum bromide. Al(s) + Br 2 (l) AlBr 2 (s)
Reacts: tells us what is reacting with what We use a + to represent reacts/reacts with Yields/To form: tells us what the product(s) is We use an to represent yields/produces/to form * We state the state of the matter for each substance. (solid, liquid, gas, or aqueous
Carbon monoxide gas and oxygen gas react to yield carbon dioxide gas. CO(g) + O 2 (g) CO 2 (g)
Solid (s) Liquid (l) Gas (g) Aqueous (aq) ◦ Use the context clues of the word equation to determine the states of matter of the reactants and products.
Notice that some of the elements have a 2 after them in their skeletal equations: These are called diatomics: ◦ These are elements exist in nature as two atoms of the same element together, ONLY when they are not bonded to another element. CO(g) + O 2 (g) CO 2 (g) Al(s) + Br 2 (l) AlBr 2 (s)
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