Answer all Problems: Why is it unwise to haphazardly mix household chemicals or

Question

Answer all Problems:

Why is it unwise to haphazardly mix household chemicals or other chemicals? How could you detect the presence of the NH4 + ion? How could you detect the presence of the CO3 2- ion? How could you detect the presence of the Cl- ion? How could you detect the presence of the SO4 2- ion? How could you detect the presence of the l- ion? How could you detect the presence of the Ag+ ion? Complete and balance the following equations: Why should distilled water be used when conducting chemical tests? Assume that you had a mixture of solid Na2CO3 and NaCl. Could you use only H2SO4 to determine whether Na2CO, was present? Explain. Assume that you had a mixture of solid Na2CO3 and NaCl. How could you show the presence of both carbonate and chloride in this mixture? How could you show the presence of both iodide and sulfate in a mixture?

Explanation / Answer

Q. Why is it unwise to haphazardly mix household chemicals?

Ans - Mixing some chemicals together can produce noxious byproducts. For example, bleach and ammonia produce chlorine gas

Q. How can you detect the presence of NH4+ ion?

Ans - Add dilute NaOH and warm. Then carry out the test for NH3. Ammonia turns red litmus paper blue.

Q. How can you detect the presence of CO3 2- ion?

Ans - Heating the compound will give offf Carbon Dioxide gas which in turn will turn lime water milky.

Q. How can you detect the presence of Cl- ion?

Ans - By adding silver nitrate to the compound. If a White precipitate is formed, then it means chloride ion is present.

Q. How can you detect the presence of SO4 2- ion?

Ans - Firstly add some AgNO3. You should see that no precipitate forms. If it forms a precipitate, it is not a SO42-. Then add some BaCl2 - If there are SO42- ions a white precipitate will form.

Q. How can you detect the presence of I- ion?

Ans - All iodide salts are soluble in water,hence make a sol,add a few drops of chloroform,& then add chlorine water,which displace free iodine & gives a violet color to the upper organic layer.

Q. How can you detect the presence of Ag+ Ion?

Ans - An easy chemical test is to add a solution containing chloride ion (sodium chloride solution works) to the solution you think contains the silver (Ag+) ion. If it does contain silver, a white precipitate of silver chloride will form and sink to the bottom. As a further confirmation, the precipitate will dissolve in ammonium hydroxide solution (ammonia water).

Ans 8 -

2LiCl + H2SO4 -> Li2SO4 + 2HCl

NH4{+}(aq) + OH{-}(aq) -> NH4(OH)(s)

AgNo3 + I- -> AgI + No3-

NaHCO3(s) + H+(aq)= Na+(aq) + CO2(g) + H2O(aq).

Ans 9 -

You know that ordinary water is not 100% pure. It means that it contains the active ions(+ve or -ve) of other elements like metals, halogens, etc.

And a chemical reaction is all about exchange of ions between the reactants.

If you are not going to use distilled water, then it means that you are involving the unwanted ions (the impurities) also in the reaction along with the ions of your reactants.

These unwanted ions will interrupt with your expected chemical reaction and form unexpected compounds with the actual reactant ions.

This is why we use distilled water for performing chemical reactions.

Ans 10 -

Yes u can determine:

when H2SO4 is added to Na2CO3 it yields CO2,

when H2SO4 is added to NaCl it does not yield any characteristic gas

therefore Na2CO3 can be easily determined by checking the presence of CO2

to check the presence of CO2 you have to just bring a burning match stick and if it switches off then CO2 is present or pass the gas thriugh lime water if it turns milky it confirms the presence of CO2 and therefore it confirms the presence of Na2CO3.

Ans 11-

First do a flame test on the solid mixture. Look for the bright yellow color in the flame to confirm Sodium. Also check with a Cobalt filter to rule out any Potassium (the blue glass will mask the yellow Sodium flame so you can see any Potassium).

Next dissolve some of the solid mixture in water. Look to make sure that it all dissolves and does not form any bubbles on its own. Add a few drops of dilute Nitric acid. You should now see bubbles develop in the solution. These are Carbon dioxide from the reaction:

Na2CO3 (aq) + 2 HNO3 (aq) --> CO2 (g) + 2 NaNO3 (aq) + H2O (l)

When all of the CO2 has been released, next add aqueous Silver Nitrate. This will react with the Chloride anions:

AgNO3 (aq) + NaCl (aq) --> AgCl (s) + NaNO3 (aq)

The Silver chloride is a white precipitate.

Ans 12 -

If your sample is a solid mixture,

Heat a small portion in a test tube, if you see IODINE condensed on cooler portion of test tube , it confirms IODINE.

For SO4--- Take a small portion and dissolve in water, Iodine will not dissolve but if soluble SO4 is there it will dissolve. Now either filter or let it stand and take clear liquid from the top and add BaCl2 solution and if white precipitate forms it confirms the presence of SO4.

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