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Chemical Equations and Reactions. Describing Chemical 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.
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Chemical Equations and Reactions Describing Chemical 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 (NH4)2S(aq) + Cd(NO3)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: Na2O(s) + H2O(l) 2 NaOH(aq)
Write formula equations for each of the following chemical reactions. • Hydrogen peroxide in an aqueous solution decomposes to produce oxygen and water. • Solid copper metal reacts with aqueous silver nitrate to produce solid silver metal and aqueous copper (II) nitrate. • Solid zinc metal reacts with aqueous copper (II) sulfate to produce copper metal and aqueous zinc sulfate.
Translating Chemical Equations PbCl2 (aq) + Na2CrO4 (aq) PbCrO4(aq) + 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: • 2 ZnO(s) + C(s) 2 Zn(s) + CO2(g) • Na2O(s) + 2 CO2(g) + H2O(g) 2 NaHCO3(s)
Write and balance equations for each of the following reactions: • Calcium metal reacts with water to form aqueous calcium hydroxide and hydrogen gas. • Nitrogen dioxide gas reacts with water to form nitric acid and nitrogen monoxide gas. • Potassium chlorate decomposes to form potassium chloride and oxygen.
Synthesis • Iron corrodes in the presence of oxygen forming iron (III) oxide. • Ammonia is formed by the combination of nitrogen and hydrogen at high temperatures and pressure.
Decomposition • The electrolysis of water results in the formation of hydrogen and oxygen. • When heated, sodium bicarbonate decomposes to sodium carbonate, water, and carbon dioxide.
Single Replacement • The addition of hydrochloric acid to magnesium results in the formation of hydrogen gas and magnesium chloride. • Sodium reacts violently with water, resulting in the formation of sodium hydroxide and hydrogen gas.
Double Replacement • When aqueous solutions of potassium iodide and lead (II) nitrate are mixed, a solid precipitate forms: lead (II) iodide. • Hydrochloric acid is neutralized by addition of a base (sodium hydroxide) resulting in the formation of water and a salt.
Combustion • Ethanol (C2H5OH) burns in oxygen, producing carbon dioxide and water. • Welders use acetylene (C2H2) torches. The flame is produced as acetylene burns in the presence of oxygen.
Using the Activity Series Zn(s) + H2O(l) no reaction Sn + O2 SnO2 Cd + Pb(NO3)2 Cd(NO3)2 + Pb Cu + HCl no reaction
Will the following reactions occur? MgCl2(aq) + Zn(s) Al(s) + H2O(g) Cd(s) + O2(g) I2 (s) + KF