Presentation on theme: "Chemical Equations and Reactions Describing Chemical Reactions."— Presentation transcript:
Chemical Equations and Reactions Describing Chemical Reactions
What are some signs that a chemical reaction is occurring?
Indications of a Chemical Reaction In a chemical reaction, one or more substances are changed into one or more NEW substances. Indications of a chemical reaction include signs that a new substance has formed.
Indications of a Chemical Reaction 1. Evolution of heat and/or light
Indications of a Chemical Reaction 2. Production of a gas Vinegar + baking soda
Indications of a Chemical Reaction 3. Formation of a precipitate (NH 4 ) 2 S (aq) + Cd(NO 3 ) 2 (aq)
Indications of a Chemical Reaction 4. Color Change Phenolphthalein + NaOH
Writing Chemical Equations Solid sodium oxide is added to water at room temperature and forms sodium hydroxide (dissolved in water). Write the word equation: Sodium oxide + water sodium hydroxide Write the formula equation: Na 2 O (s) + H 2 O (l) 2 NaOH (aq)
Write formula equations for each of the following chemical reactions. 1.Hydrogen peroxide in an aqueous solution decomposes to produce oxygen and water. 2.Solid copper metal reacts with aqueous silver nitrate to produce solid silver metal and aqueous copper (II) nitrate. 3.Solid zinc metal reacts with aqueous copper (II) sulfate to produce copper metal and aqueous zinc sulfate.
Translating Chemical Equations PbCl 2 (aq) + Na 2 CrO 4 (aq) PbCrO 4 (s) + 2 NaCl (aq) Write a sentence explaining the above reaction: Aqueous solutions of lead (II) chloride and sodium chromate react to form a precipitate of lead(II) chromate and aqueous sodium chloride.
Translate the following into sentences: 1.2 ZnO (s) + C (s) 2 Zn (s) + CO 2 (g) 2.Na 2 O (s) + 2 CO 2 (g) + H 2 O (g) 2 NaHCO 3 (s)
Write and balance equations for each of the following reactions: 1.Calcium metal reacts with water to form aqueous calcium hydroxide and hydrogen gas. 2.Nitrogen dioxide gas reacts with water to form nitric acid and nitrogen monoxide gas. 3.Potassium chlorate decomposes to form potassium chloride and oxygen.
Classification of Reactions Today’s objective: Classify reactions according to five general types: Synthesis Decomposition Single replacement Double replacement Combustion
Synthesis 1.Iron corrodes in the presence of oxygen forming iron (III) oxide. 2.Ammonia is formed by the combination of nitrogen and hydrogen at high temperatures and pressure. General Form: Description: Burning Magnesium video
Decomposition 3.The electrolysis of water results in the formation of hydrogen and oxygen. 4.When heated, sodium bicarbonate decomposes to sodium carbonate, water, and carbon dioxide. General Form: Description: Decomposition of HgO
Single Replacement 5.When Magnesium is added to an aqueous solution of copper (II) chloride, a precipitate of copper is formed along with a solution of magnesium chloride 6.Sodium reacts violently with water, resulting in the formation of sodium hydroxide and hydrogen gas. General Form: Description: Thermite Reaction
Double Replacement 7.When aqueous solutions of potassium iodide and lead (II) nitrate are mixed, a solid precipitate forms: lead (II) iodide. 8.Hydrochloric acid is neutralized by addition of a base (sodium hydroxide) resulting in the formation of water and a salt. General Form: Description: Potassium iodide + lead (II) nitrate
Combustion 9.Ethanol (C 2 H 5 OH) burns in oxygen, producing carbon dioxide and water. 10.Welders use acetylene (C 2 H 2 ) torches. The flame is produced as acetylene burns in the presence of oxygen. General Form: Description: Burning Gasoline and Ethanol