Lab. lesson problems Someone plx HELP me~

[b]La Salle College proudly presents:

[b]Identification of four unknown solids[/b]
You are given four unknown solids, namely magnesium sulphate(MgSO4), potassium sulphate (K2SO4), zinc(II)sulphate (ZnSO4), ammonium sulphate [(NH4)2SO4].

Decide your own procedures to identify the four unknown solids by using the given reagents:
dilute sodium hydroxide solution (dil.NaOH), water (H2O)

Write down your own procedures, observations and inference.

Someone got to help me. Espcially those "Oxfords". Deadline 9-12. Thx so much.

Sorry for poor English.


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You are going to be given four solids. Select one, and dissolve [b]some[/b] of it in water. [u]Ammonium Sulfate[/u] will begin to emit ammonia, which has a very strong odor; you can't miss it. If no odor is present, add a couple drops of dilute sodium hydroxide. If no precipitation occurs, then the powder is [u]Potassium Sulphate[/u]. Otherwise, it will produce precipitate, which implies the solid is either MgSO[size=9]4[/size] or K[size=9]2[/size]SO[size=9]4[/size]. In this case, take a close look at the crystals. [u]Magnesium Sulfate[/u] (Epsom salt) aree rod-shaped, while [u]Zinc Sulfate[/u] crystals are not rod-shaped. Based on these observations you should be able to tell which solid you are trying to identify. Follow the same procedure for the remaining solids, until you have successfully identified all solids.

It's not true actually with magmesiun sulphate and zinc sulphate. Excess NaOH with redissolve the pecipitate of zinc hydroxide while it does not happen in magmesiun hydroxide.
The smell of ammonia gas is really good.

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