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3. The table below gives some properties of gas [tex]$D$[/tex] and [tex]$E$[/tex]:

\begin{tabular}{|l|l|l|l|l|}
\hline
Gas & Density & Effect on [tex]$H_2SO_4$[/tex] & Effects on NaOH \\
\hline
D & Lighter than air & Reacts to form salts & Dissolves without reacting \\
\hline
E & Heavier than air & Not affected & Not affected \\
\hline
\end{tabular}

(a) Describe how you would obtain a sample of gas E from a mixture of gases D and E.

Insert the mixture of the gases in a gas jar. Insert a tube vertically through the upper part. Gas D, being lighter than air, will rise to the top and be vented out through the tube while gas E will settle at the bottom.

(b) Since it is denser than air, what is the possible identity of gas D? Give reasons for your answer.



Answer :

GinnyAnswer
Sure! Let's address each part of the question systematically.

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### (a) Describe how you would obtain a sample of gas E from a mixture.

To separate gas E from a mixture, you'll need to utilize the differences in their densities:

1. Set Up a Gas Jar: Place the mixture of gases D and E into a gas jar.

2. Insert a Vertical Tube: Insert a tube vertically through the upper portion of the gas jar.

3. Collect Gas D: Gas D, being lighter than air, will naturally rise to the top of the jar. As it rises, it can be vented out through the tube inserted at the top.

4. Collect Gas E: Once gas D has been vented out, gas E, being heavier than air, will settle at the bottom of the jar. This allows you to easily collect gas E from the bottom of the jar.

By following these steps, you can efficiently separate and collect gas E from the mixture.

### (b) Possible identity of gas D. Give reason for your answer.

Given the properties of gas D:

- Lighter than air: This indicates that the molar mass of gas D is less than the molar mass of the average air (approximately 29 g/mol).

- Reacts with [tex]\(H_2SO_4\)[/tex] to form salts: This means gas D participates in a chemical reaction with sulfuric acid, forming a salt.

- Dissolves in NaOH without reacting: This suggests solubility in an aqueous base solution (NaOH) without undergoing a chemical reaction.

A possible candidate for gas D is Ammonia (NH[tex]\(_3\)[/tex]):

- Lighter than air: Ammonia has a molar mass of approximately 17 g/mol, which is indeed less than the molar mass of air.

- Reacts with [tex]\(H_2SO_4\)[/tex]: Ammonia reacts with sulfuric acid to form ammonium sulfate [tex]\((NH_4)_2SO_4\)[/tex].

- Dissolves in NaOH: Ammonia is soluble in an aqueous solution of sodium hydroxide, forming ammonium ions [tex]\(\left( NH_4^+ \right)\)[/tex] in the solution without further reacting.

Therefore, based on these characteristics, the possible identity of gas D is Ammonia (NH[tex]\(_3\)[/tex]).

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By following these detailed steps and understanding the properties of the gases, you can effectively separate and identify them.

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