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A 5.00 mL sample of hydrochloric acid is titrated with 0.1293 M ammonia (a base). If the titration required 28.15 mL of ammonia, determine the following:
the original concentration of the acid
the original pH of the acid

Respuesta :

Answer:

1. C = 0.73 M.

2. pH = 0.14

       

Explanation:

The reaction is the following:

HCl + NH₃ ⇄ NH₄⁺Cl⁻

From the titration, we can find the number of moles of HCl that were neutralized by the ammonia.

[tex] n_{a} = n_{b} [/tex]

Where "a" is for acid and "b" is for base.

The number of moles is:

[tex] n = C*V [/tex]  

Where "C" is for concentration and "V" for volume.

[tex] C_{a}V_{a} = C_{b}V_{b} [/tex]

[tex] C_{a} = \frac{0.1293 M*28.15 mL}{5.00 mL} = 0.73 M [/tex]

Hence the initial concentration of the acid is 0.73 M.

The original pH of the acid is given by:

[tex] pH = -log([H^{+}]) [/tex]

[tex] pH = -log(0.73) = 0.14 [/tex]          

Therefore, the original pH of the acid is 0.14.

I hope it helps you!