ii The most common type of precipitation reaction is a double displacement

Ii the most common type of precipitation reaction is

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ii. The most common type of precipitation reaction is a double displacement reaction or metathesis reaction. 1. This reaction can also be referred to as an exchange reaction. 2. Example: 2KBr( aq ) + Pb(NO 3 ) 2 ( aq ) barb2right PbBr 2 ( s ) + 2KNO 3 ( aq ) iii. To predict precipitation reactions, the solubilities of reactants and products must be assessed. 1. If all reactants and products are soluble in water, no product results. 2. If one or more products is insoluble, the reaction will proceed and a solid substance will be observed. b. Acid–base neutralization reactions i. An acid and base are combined to form an ionic compound (i.e. salt) and possibly water (if the base is a hydroxide). ii. A Brønsted–Lowry acid is defined as a proton donor. 1. Example: HBr or H 2 SO 4 iii. A Brønsted–Lowry base is defined as a proton acceptor. 1. Example: LiOH or NH 3 iv. An example reaction: LiOH( aq ) + HBr( aq ) barb2right LiBr( aq ) + H 2 O( l ) v. Some ionic salts, when reacted with acid, form gases. 1. The most common gases produced are CO 2 , SO 2 , and H 2 S. 2. Example: K 2 CO 3 ( aq ) + 2HBr( aq ) barb2right 2KBr( aq ) + H 2 O( l ) + CO 2 ( g ) a. The H 2 O( l ) + CO 2 ( g ) result from the spontaneous decomposition of H 2 CO 3 ( aq ). c. Oxidation–reduction reactions i. These reactions involve electron transfer where one species is oxidized and another species is reduced. 1. Oxidation: loss of electrons or an increase in the oxidation number. 2. Reduction: gain of electrons or a decrease in the oxidation number. ii. The most common types of oxidation–reduction reactions are: 1. Combination (or synthesis) reactions 2. Decomposition reactions 3. Single displacement reactions Experiment #4 Barnett
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4. Combustion reactions 2) There are a number of driving forces for reactions to occur: a. Formation of molecular compounds i. Example: H 2 O b. Formation of a gas i. Examples: H 2 S, CO 2 , SO 2 c. Formation of an insoluble precipitate i. See Table A attached for a comprehensive list of soluble and insoluble salts in water. Introduction to Double Displacement Reactions : 1) A double displacement reaction (or metathesis reaction) is one in which two ionic compounds in an aqueous solution exchange anions to produce two new species. 2) The driving force for this type of reaction is typically the production of an insoluble precipitate. a. If all products are soluble, no reaction will take place. 3) Most double displacement reactions can be predicted by analyzing water solubility of the products. 4) An example precipitation reaction is depicted below. a. Al 2 (SO 4 ) 3 ( aq ) + 6NaOH( aq ) barb2right 2Al(OH) 3 ( s ) + 3Na 2 SO 4 ( aq ) 5) Most acid–base neutralization reactions can also be classified as double displacement reactions. The Experimental Goal : 1) The goal of this experiment is to identify seven aqueous solutions using qualitative analysis. a. Qualitative analysis is a systematic method of recording precipitation reactions, color changes, and other visible changes to determine chemical composition.
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  • Spring '19
  • Chemistry, Chemical reaction, Timothy Barnett

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