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# double displacement reaction example

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Question:I've learnt in Chemistry class about reactions between two aqueous compounds, but is it possible for there to be a reaction between an aqueous compound and an insoluble compound? If it is, what are the requirements? Would it involve the activity series, somehow? Examples would be appreciated.

Answers:Yes, a reaction can occur between an aqueous compound and an insoluble compound, but it occurs only on the surface, unless the precipitate does not adhere to the reactant, and therefore falls off, exposing more solid to the solution. This is therefore usually not a useful method for preparing an insoluble solid. One example is the reaction between calcium carbonate and sulfuric acid. Fizzing occurs initially, but calcium sulfate builds up on the surface, and calcium carbonate stops dissolving. CaCO3(s) + H2SO4(aq) -----> CaSO4(s) + CO2(g) + H2O(l) (This is actually an acid-base reaction.) Another example is Ag2O(s) + 2HI(aq) -----> 2AgI(s) + H2O(l) This reaction occurs because AgI is more insoluble than Ag2O.

Question:What is the main difference between a double displacement reaction and an acid-base reaction?

Answers:Suppose you mix the following solutions: (a) NaCl(aq) + AgNO3(aq) ------> (b) NaCl(aq) + Fe(NO3)2(aq) -------> Which one gives a double replacement (displacement) reaction? Answer is (a). Why? Complete the equations. (a) NaCl(aq) + AgNO3(aq) ------> NaNO3(aq) + AgCl(s) (b) NaCl(aq) + Fe(NO3)2(aq) -------> Na^+(aq) + Cl^-(aq) + Fe^2+(aq) + 2NO3^-(aq) (in other words no reaction) Can you recognize the difference. In (a), a slightly soluble salt AgCl is formed, that is a precipitation occurs. But in (b), even if the anions or cations are displaced, the formed salts NaNO3 and FeCl2 are also soluble and there will not be a separation of substance occur. All 4 ions will be present in the solution. Similarly an acid-base reaction is also a displacement reaction. But, why a neutralization reaction occurs, although it does not produce an insoluble salt? This time, instead of a slightly soluble salt, a slightly ionizable substance (WATER) is formed. Therefore 4 ions are not present. For example: NaOH(aq) + HCl(aq) -----> NaCl(aq) + H2O(l) But not; NaOH(aq) + HCl(aq) -----> Na^+(aq) + Cl^-(aq) + H^+(aq) + OH(aq) Therefore a neutralization takes place. Displacement reaction: a slightly soluble salt formed Neutralization reaction: a slightly ionizable water formed But in general both of them are double replacement reactions.

Question:u have 2 hours to answer thanks

Answers:When refering to bronsted-lowery acid base reactions, then it just a sub-type of double displacement.

Question:What type of reaction is the following? 2Fe2O3 + 3C -> 4Fe + 3CO2 Why is this not considered to be a single-displacement reaction? Provide two written definitions of an oxidation-reduction reaction. For each definition, tell which reactant in the above reaction is reduced and which is oxidized. Which of the two definitions is the most comprehensive? ...I don't get why it's not single-displacement...please help! @pisgahchemist: Why doesn't it classify as a single-dis/replacement reaction? What technically keeps it from being considered as such?

Answers:There are many, many reactions which do not fit the format of the common synthesis, decomposition and single and double replacement reactions. There are many more reactions which we classify as "redox" reactions, and while single replacement reactions are also redox reactions, there are many redox reactions which are not single replacement reactions. Oxidation-reduction reactions involve the simultaneous transfer of electrons such that one element is being oxidized (loss of electrons, increase in oxidation number), and another element is being reduced (gain of electrons, decrease in oxidation number). 2Fe2O3 + 3C -> 4Fe + 3CO2 In your example, iron is being reduced and carbon is being oxidized. The iron appears to be gaining 3 electrons per atom while the oxidation number decreases (being reduced, so to speak). Carbon appears to be losing four electrons while the oxidation number is increasing from 0 to +4. Keep in mind that in Fe2O3 iron does not have an actual charge of +3, and carbon does not have an actual charge of +4. Those are the oxidation numbers. The electron "transfer" is actually being mitigated by the oxygen which does not change its oxidation number. ----------- Follow up ----------- Typically a single replacement reaction occurs when one metal replaces another one in a compound, or when one halogen replaces another one. In this case the oxygen is originally part of a metal oxide, and then goes to a nonmetal oxide. The general format for single replacement is this: "An element and a compound react to form an element and a compound". I suppose from that standpoint you could call it single replacement.