Question

respond to all 3 pls

13. Water and hexane do not mix, but a solution can be formed of water, ethanol, and hexane. Propose and explanation. (5 Pts) 14. A mixture of 3 gasses is collected over water at 30°C has total pressure of I atm. If gas A 35% of the pressure and gas B is 35% of the pressure, what is the pressure of gas C? (5 Pts) 15. The following hypothetical compound Nn NpNo is a salt of a polyatomic. How many moles of ions can be found in a 0.335 M solution? (5 Pts)

Answer 1

13. It is true that water and hexane are not miscible. At the same time water and ethanol are miscible. Again hexane and ethanol are miscible. So if we made two separate solutions by mixing i) water and ethanol, and ii) hexane and ethanol; and after that these two solutions are mixed at particular volume ratio, a solution of these three can be made. Please note that, the concentration of hexane should not be too high, otherwise it will be immiscible in the solvent when two solutions are mixed.

14. In a mixture of gases, total pressure of the gas mixture can is iqual to the partial pressure of all the gases present in the mixture. Now in the given mixture of gases contains three gases (A, B, and C). The total pressure of the gas mixture is 1 atm at 30 oC.

Now the pressure of gas A = 35% of the total pressure.

Therefore partial pressure of gas A = (35/100) $\times$ 1 atm = 0.35 atm.

The pressure of gas B = 35% of the total pressure.

Therefore partial pressure of gas B = (35/100) $\times$ 1 atm = 0.35 atm.

Now total pressure of the gas can be expressed as

Ptotal = Partial pressure of gas A + Partial pressure of gas B + Partial pressure of gas C

Therefore, Partial pressure of gas C = Ptotal - (Partial pressure of gas A + Partial pressure of gas B)

= 1.0 atm - (0.35 atm + 0.35 atm)

= 0.30 atm

Here partial pressure of C = pressure of C = 0.30 atm.

15. Lets check the ionization of hypothetical compound in solution

Nn2NpNo (s)  $\rightleftharpoons$ 2Nn+ (aq) + NpNo2- (aq)

So in solution one polyatomic salt is dissociated into 3 ions (two Nn+ ions, and one NpNo2- ion).

Therefore total concentration of ions in solution will be three times more than the polyatomic salt.

In other words, 1 M solution of the polyatomic salt produces 3 M of ions in solution

Therefore 0.335 M solution of the polyatomic salt will produce = 3 $\times$ 0.335 M = 1.005 M of ions.

So in solution 1.005 M of ions can be found in a 0.335 M solution of the polyatomic salt.

Please note: In this question it is asked how many moles of ions can be found in 0.335 M solution of the polyatomic salt. The question is technically wrong because M stands for molar concentration. So if the volume of the solution is not mentioned, it is not possible to convert the molar concentration of the salt into moles. Therefore the number of moles of ions can not be determined. Here only the total molar concentration of ions can be dtermined and this is done here.

If it was asked how many moles of ions can be found in a solution which contain 0.335 moles of polyatomic salt, the answer would be 1.005 moles.

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