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Types of Chemical Reactions. Synthesis Reactions. Smaller atoms/compounds combine to form larger molecules Also known as combination or addition reactions. A + B AB. 2H 2 + O 2 2H 2 O. Synthesis Reaction. Synthesis Reactions -Examples.
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Synthesis Reactions • Smaller atoms/compounds combine to form larger molecules • Also known as combination or addition reactions A + B AB 2H2 + O2 2H2O
Synthesis Reactions -Examples ii) A metal reacts with a non-metal to form a binary compound K(s) + Cl2(g) KCl(s) • Is this equation balanced? i) A metal reacts with oxygen to produce an oxide Na(s) + O2(g) Na2O(s) • Is this equation balanced? iii) A compound reacts with an element to form a new compound PCl3 (l) + Cl2(g) PCl5(s) • Is this equation balanced?
Oxides • When an element combines with oxygen an oxide is formed • Metals react with oxygen to form metal oxides • Metal oxides • are always solids • react in water to form basic solutions • are also called basic oxides • Recall: Properties of basic solutions • Turn red litmus blue and colourless phenolphthalein indicator pink
Metal Oxides - Example Ca(s) + O2(g) CaO(s) CaO(s) + H2O (l) Ca(OH)2(aq) 2 2 metal oxide basic solution metal hydroxide
Oxides • Non-metals react with oxygen to form non-metal oxides • Non-metal oxides • are often gases or liquids • react in water to form acidic solutions • are also called acidic oxides • Recall: Properties of acidic solutions • Turn blue litmus red and blue coloured bromothymol blue (BTB) indicator yellow
Non-metal Oxides - Example N2 (g) + O2(g) NO2 (g) NO2 (g) + H2O (l) HNO3(aq) + NO (g) 2 2 non-metal oxide 3 2 acidic solution
Decomposition Reaction • The splitting of a large molecule into elements or smaller compounds AB A + B Complimentary to synthesis reaction 2H2O 2H2 + O2
Decomposition Reactions-Examples Water decomposes into its elements H2O(l) H2(g) + O2(g) Hydrazine (a rocket fuel) decomposes N2H4 (l) NH3(g) + N2(g) 2 2 3 4
Homework • Text p 136 #3, 4, 5, 6, 7, 10, • Worksheet Oxides • Investigation 1– Read and make your prediction (on a separate sheet)