Presentation on theme: " What do you already know about chemical and physical changes? What do you already know chemical reactions?"— Presentation transcript:
What do you already know about chemical and physical changes? What do you already know chemical reactions?
Writing word and skeletal equations
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
Rotting, baking, cooking, etc.
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)
There are 7 diatomics:
Aqueous Sodium hydroxide reacts with aqueous calcium bromide to form aqueous sodium bromide and solid calcium hydroxide.
Solid zinc reacts with aqueous sulfuric acid to form hydrogen gas and solid zinc (II) sulfate.
Fe(s) + O 2 (g) Fe (s)
Solid calcium oxide reacts with water to form solid calcium hydroxide.
Gaseous sulfur dioxide and oxygen gas react to form sulfur trioxide gas.
Solid sodium reacts with chlorine gas to form solid sodium chloride.
NaCl(aq) + AgNO 3 (aq) NaNO 3 (aq) + AgCl(s)
Please complete your ticket out the door, and turn into me before packing up. HINT: Make sure you know the 7 diatomic elements tomorrow when you come in the door!