Salt+Preparation

=**Salt Preparation - Groupwork**=

The Task: To analyze and evaluate the different ways a salt can be prepared. Each group was given a salt to prepare. The group is to decide on what is the best way(s) to prepare the given salt. Remember to think about the practicalities in the procedures and the **// purity //**  of the salt produced as well.

** Rosemarie's Group **
Group members:

Possible reactions for MAGNESIUM CHLORIDE:
(Magnesium Ribbon) **Group I metals are highly reactive, therefore not used in experiments** // All chlorides are soluble except for silver and lead. // Magnesium + Hydrochloric Acid è Dissolve. FILTER out the solid after adding magnesium until it does not react anymore (all acid has completely reacted à not equal to saturated), so as to ensure purity(making it concentrated). //Purity[In this case] //// à //// Must make sure that all acid is completely reacted to the magnesium ribbon. (so that when you crystallize, all you get is the salt.) // Add more MgCO3 till it no longer reacts and filter the solution. Boil it and leave it to crystallize. Add more Mg(OH)2 till it no longer react and filter the solution. Boil it and leave it to crystallize. // (Only sodium chloride then use “evaporate to dryness”) // · Safe as Mg is not a Group I metal Easier to tell when reaction has ended as salt is soluble. Excess reactant is not soluble!--> visual indicator (: || All take long for crystallization process to take place. || End products are different for each reaction. ||
 * __ACID + REACTIVE METAL : Mg + 2HCl__ **** __à__ **** __MgCl2 + H2__ **
 * __ACID + CARBONATE: 2HCl + MgCO3__ **** __à__ **** __CO2 + MgCl­2 + H2O__ **
 * __ACID + BASE: 2HCl + Mg(OH)2__ **** __à__ **** __MgCl2 + 2H2O__ **
 * **ADVANTAGES ** || **LIMITATIONS ** || **UNIQUE FEATURES ** ||
 * Acid + reactive metal:

Jixin's Group
Group members:

Sodium nitrate (salt)
Will method will allow you to obtain a pure sample of the salt?

Acid+ Reactive metal-> H2+ Salt (Sodium nitrate)
 * **Advantages** || **Limitations** || **Unique features** ||
 * Salt can be obtained easily, as hydrogen is a gas which will be released into the air. || Hydrogen might react with substances that result in explosive reactions.

Purity of the salt is ensured as separation techniques are not needed after reaction.

NOT SAFE!:) || Sodium nitrate is a soluble salt. ||

Acid+ Base->H2O+ Salt (Sodium nitrate)
 * **Advantages** || **Limitations** || **Unique features** ||
 * No harmful products from reaction || Sodium nitrate is soluble, therefore it will mix with the H2O and therefore separation techniques is required to separate it from water.

A possibility of impurities present in the salt after separation, as most separation techniques are not 100% foolproof. || Salt can be separated through crystallization. (separation techniques) ||

Acid+ Carbonate-> CO3+ H2O+ Salt (Sodium nitrate)
 * **Advantages** || **Limitations** || **Unique features** ||
 * - || Similar limitations to Acid+ Base reaction (See above)

Carbon dioxide emission leads to global warming, therefore harmful to environment. || Salt still can be separated through crystallization.(separation techniques) ||

Acid+ -> NH3+ Salt (Sodium nitrate)+ H2O
 * **Advantages** || **Limitations** || **Unique features** ||
 * - || Similar limitations to Acid+ Base and Acid+ Carbonate reactions, with an additional step to separate NH3 from the salt (sodium nitrate).

Has the greatest possibility relatively (as compared to the rest of the reactions) for impurities present after separation.

NH3 can induce poisoning, irritates respiratory tract. || - ||

Salt: Lead (II) Sulfate
**Method of salt formation** || **Chemical equation** || **Limitation** || Acid+ reactive metal || H 2 SO 4 (aq) + Pb (s) -> H 2 (g) + PbSO 4 (s) || Only the surface of the lead will react with the acid because both reactant and product are insoluble. || Soluble salt solution + Soluble salt solution || Pb(NO 3 ) 2 (aq) + H 2 SO 4 (aq) -> PbSO 4 (s) + 2HNO 3 (aq) || To ensure the purity of the salt, wash it and dry it with filter paper. || Acid + Base || H 2 SO4 (aq) + PbO (s) -> PbSO 4 (s) + H 2 O (l) || Only the surface of the lead will react with the acid because both reactant and product are insoluble. || Acid + Carbonate || PbCO 3 (s) + H 2 SO 4 (aq) -> PbSO 4 (s) + CO 2 (g) + H 2 O (l) ||  ||



Salt: Copper (II) Nitrate / Cu(NO3)2
1. Think of all the possible reactions in which the salt can be formed.
 * Acid+Base -> Salt + Water

Nitric acid + Copper(II) sulfate ->2HNO3 + Cu(SO4)2 = 2H2O + Cu(NO3)2 +SO2 (Sulphur dioxide)
 * Acid + Carbonate -> CARBON DIOXIDE + WATER + SALT

Nitric Acid + Copper (II) Carbonate -> CO2 + H2O + Cu(NO3)2
 * Acid + Reactive metal -> HYDROGEN + SALT

NO REACTION
 * Alkali + Ammonium salt -> AMMONIA(G) + SALT + WATER

Copper Hydroxide + Ammonium Nitrate-> NH3 + Cu (NO3)2 + H2O

2. Evaluate each reaction and consider if it provides a practical and possible method in which the salt can be prepared. there will be no reaction for the third one Advantages: there will be no explosive reactions for the first reaction (acid and base) Disadvantages: It might be difficult to extract the pure copper(II) nitrate from the solution of copper (ii) nitrate, water and ammonia Limitations ("How might..."/ "How to..."): We should be careful when mixing the various chemicals, as some chemicals, when mixed together, will become violatile and this might result in an explosion.

3. Finally decide on which is/are the best way(s) the salt can be prepared. Preparing salts by neutralisation with oxides and carbonates **1** An insoluble **metal oxide** reacts with a **dilute acid** to form a **soluble salt**. **Copper(II) oxide**, a black solid, and colourless dilute **sulfuric acid** react to produce **copper(II) sulfate**, giving a characteristic blue colour to the solution. Blue copper(II) sulfate pentahydrate crystals are obtained from this solution **2** An insoluble **metal carbonate** reacts with a **dilute acid** to form a **soluble salt**. **Magnesium carbonate**, a white solid, and dilute **sulfuric acid** react to produce **magnesium sulfate**. Colourless magnesium sulfate heptahydrate crystals are obtained from this solution.

ammonium nitrate
1) Acid + Base -> Salt + H20 Nitric acid + Ammonium hydroxide -> Ammonium nitrate + water [HNO3] (aq) + [NH4OH] (aq) -> [NH4NO3] (aq) + [H2O] (l) Advantages: Safe Limitations: How do you make sure if it's completely reacted? Do it in such a way where there's excess acid and no excess base and then you put reactive metal inside to react with acid to form hydrogen and water and salt and on the condition that the salt formed has to be insoluble. And then filter!!!! Get rid of residue and filtrate will be ammonium hydroxide and water!!!!! when reacting acid with reactive metal, add metal until no more reaction to ensure that acid and metal have completely reacted. Unique features: NIL 2) Acid + Carbonate -> CO2 + H2O + Salt Nitric acid + Ammonium Carbonate -> Ammonium nitrate + Carbon dioxide + Water 2[HNO3] (aq) + [(NH4)2CO3] -> 2[NH4NO3] (aq) + [CO2] (g) + [H2O] (l) Advantages: Safe Limitations: How do you ensure that they have completely reacted? Refer to above!! unique features: NIL

3) Acid + Reactive metal -> Hydrogen + Salt Not possible because ammonium is not a metal.

4) Alkali + Ammonium salt -> Ammonia gas + Salt + Water Not possible: Will result in ammonia gas being formed which means that salt cannot be ammonium nitrate.