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12. After the two solutions in Q11 are mixed, write an equation that shows what

ID: 716060 • Letter: 1

Question

12. After the two solutions in Q11 are mixed, write an equation that shows what happens when 0.00500 mole of HCl(aq) is added to the solution. 13. A 20.0 mL aqueous solution of 0.10 M CH2CH2NH3+, Cl(aq) ethylamine hydrochloride, is with stirring to a 20.0 mL aqueous solution of 0.10 M CH3CH2NH2(aq), ethylamine. Write n equation that represents the resultant solution. Is the resultant solution acidic, basic, or neutral? dded 4. After the two solutions in Q13 are mixed, write an equation that shows what happens when 00500 mole of HCI(aq) is added to the solution.

Explanation / Answer

Solution :-

Q13) CH3CH2NH3^+ is the conjugate acid of the CH3CH2NH2

Using the same volume and same concentration of the both conjugate and acid in the mixture gives the pH of solution equal to its pka value

Concentration of the both after mixing will be halved because volume of the final solution is double than initial individual volumes

Total volume = 20 ml + 20 ml = 40 ml

New concentrations are calculated using the dilution formula

M1V1=M2V2

M2 = M1V1/V2

[CH3CH2NH3^+] = 0.10 M*20 ml / 40 ml = 0.05 M

[CH3CH2NH2] = 0.10 M*20 ml / 40 ml = 0.05 M

Pka of the conjugate acid CH3CH2NH3^+ is 10.63

pH= pka + log [base /acid ]

pH= 10.63 + log [0.05 /0.05]

pH= 10.63

Since the pH of the solution is higher than 7 that means solution is basic in nature.

Q14 )

When the 0.00500 moles of HCl is added to the solution of the CH3CH2NH2 and CH3CH2NH3^+ then HCl reacts with ethyl amine which is base and forms more conjugate acid CH3CH2NH3^+

The reaction equation is as follows

CH3CH2NH2 + HCl --- > CH3CH2NH3+ + Cl-