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

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.

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

The number of moles is:

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

Hence the initial concentration of the acid is 0.73 M.

The original pH of the acid is given by:

Therefore, the original pH of the acid is 0.14.

I hope it helps you!                  

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.