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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Win,odd Dhamnekar on April 07, 2023, 10:40:21 AM

Title: Analysing the reaction to find out empirical formula
Post by: Win,odd Dhamnekar on April 07, 2023, 10:40:21 AM
QuestionA mixture of xenon and fluorine was heated. A sample of the white solid that formed reacted with hydrogen to yield 81 mL of xenon (at STP) and hydrogen fluoride, which was collected in water, giving a solution of hydrofluoric acid. The hydrofluoric acid solution was titrated, and 68.43 mL of 0.3172 M sodium hydroxide was required to reach the equivalence point. Determine the empirical formula for the white solid and write balanced chemical equations for the reactions involving xenon.
My answer:
Let's start by determining the amount of hydrogen fluoride produced in the reaction between the white solid and hydrogen. The volume of sodium hydroxide solution required to reach the equivalence point in the titration of the hydrofluoric acid solution is 68.43 mL, and the concentration of the sodium hydroxide solution is 0.3172 M. So, the number of moles of sodium hydroxide used in the titration is (68.43 mL) * (0.3172 mol/L) * (1 L/1000 mL) = 0.0217 moles.

Since the reaction between sodium hydroxide and hydrofluoric acid is a 1:1 reaction (NaOH + HF :rarrow: NaF + H2O), this means that 0.0217 moles of hydrofluoric acid were produced in the reaction between the white solid and hydrogen.

Now let's determine the amount of xenon produced in the reaction between the white solid and hydrogen. The volume of xenon produced is 81 mL at STP (standard temperature and pressure). At STP, one mole of any gas occupies a volume of 22.4 L. So, the number of moles of xenon produced in the reaction is (81 mL) * (1 L/1000 mL) * (1 mol/22.4 L) = 0.00362 moles.

Since both xenon and hydrogen fluoride are produced in a 1:6 ratio in the reaction between the white solid and hydrogen, this means that the empirical formula for the white solid is XeF6.

The balanced chemical equations for the reactions involving xenon are:

Xe + 3F2  :rarrow: XeF6 (formation of the white solid)
XeF6 + H2  :rarrow: Xe + 6HF (reaction between white solid and hydrogen)
HF + NaOH  :rarrow: NaF + H2O (titration of hydrofluoric acid with sodium hydroxide)


In my opinion, this answer is correct. Isn't it? 
Title: Re: Analysing the reaction to find out empirical formula
Post by: Hunter2 on April 07, 2023, 01:29:14 PM
Sounds correct
Title: Re: Analysing the reaction to find out empirical formula
Post by: mjc123 on April 07, 2023, 03:30:26 PM
The second equation isn't balanced; it requires 3H2. Otherwise looks correct.
Title: Re: Analysing the reaction to find out empirical formula
Post by: Hunter2 on April 07, 2023, 03:31:47 PM
Yes correct, overlooked it.
Title: Re: Analysing the reaction to find out empirical formula
Post by: Win,odd Dhamnekar on April 08, 2023, 02:42:58 AM
The second equation isn't balanced; it requires 3H2. Otherwise looks correct.
  Thanks  for pointing out the mistake in balancing chemical equation.