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प्रश्न
You are provided with two reagent bottles marked A and B. One of which contains NH4OH solution and the other contains NaOH solution. How will you identify them by a chemical test?
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उत्तर
Reagent bottles A and B can identified by using calcium salts such as Ca(NO3)2.
When NaOH is added to Ca(NO3)2, Ca(OH)2 precipitates as a white precipitate that is sparingly soluble in excess of NaOH.
\[\ce{Ca(NO3)2 + 2NaOH -> Ca(OH)2 + 2NaNO3}\]
whereas, on addition of NH4OH to calcium salts, no precipitation of Ca(OH)2 occurs even with an excess of NH4OH because the concentration of OH−ions from the ionization of NH4OH is so low that it cannot precipitate the calcium hydroxide.
So the reagent bottle which gives white precipitate is NaOH and the other is NH4OH.
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संबंधित प्रश्न
What do you understand by the following:
Analysis
What do you understand by the following:
Qualitative analysis
What do you understand by the following:
Reagent
What do you understand by the following:
Precipitation
Match the following :
| Column A | Column B |
| 1. A substance that turns moist starch iodide paper blue. |
A. Ammonium sulphate |
| 2. A compound which releases a reddish brown gas on reaction with concentrated sulphuric acid and copper turnings. |
B. Lead carbonate |
| 3 . A solu tion of this compound gives a dirty green preci pi ta te with sodium hydroxide. |
C. Chlorine |
| 4 . A compound which on heating with sodium hydroxide produces a gas which forms dense white fumes with hydrogen chloride. |
D. Copper nitrate |
| 5 . A white solid which gives a yellow residue on heating. |
E. Ferrous sulphate |
Identify the substance ‘R’ based on the information given below:
The pale green solid ‘R’ turns reddish brown on heating. Its aqueous solution gives a white precipitate with barium chloride solution. The precipitate is insoluble in mineral acids.
From the list given below, select the word(s) required to complete the blanks (i) to (v) in the following passage:
Note : words chosen from the list are to be used only once. Write only the answers. Do not copy the passage.
[reddish brown, ammonium, nitrogen dioxide, hydroxyl, dirty green, ammonia, acidic, alkaline]
Nitrogen and hydrogen combine in the presence of a catalyst to give (i) ______ gas. When the above mentioned gas is passed through water it forms a solution which will be (ii) ______ in nature and the solution contains (iii) ______ ions and (iv) ______ ions. The above solution when added to iron (II) sulphate solution gives a (v) ______ coloured precipitate of iron (II) hydroxide.
The salt which in solution gives a pale green precipitate with sodium hydroxide solution and a white precipitate with barium chloride solution is ______.
Write balanced equation for a coloured metallic oxide which dissolves in alkalis to yield colourless solutions.
Write balanced equations for a coloured metallic oxide which dissolves in alkalis to yield colourless solutions.
