A 23.74-mL volume of 0.0981 M NaOH was used to titrate 25.0 mL of a weak monoprotic acid solution to the stoi- chiometric point. Determine the molar concentration of the weak acid solution. Express your answer to the correct number of significant figures.

Molar concentration of the weak acid solution is 0.0932

Explanation:

Using the formula:

Where Ca = molarity of acid

Cb = molarity of base = 0.0981 M

Va = volume of acid = 25.0 mL

Vb = volume of base = 23.74 mL

na = mole of acid

nb = mole of base

Since the acid is monopromatic, 1 mole of the acid will require 1 mole of NaOH. Hence, na = nb = 1

Therefore,

Ca = 0.0981 x 23.74/25.0

                 = 0.093155 M

To 4 significant figure = 0.0932 M

Explanation:

Given:

Vb = 23.74 mL

Cb = 0.0981 M

Va = 25.0 mL

Since the weak acid is monoprotonic. Therefore, 1 mole of NaOH reacts with 1 mole of acid. By stoichiometry, the number of moles of acid = molar conc. × volume

= 0.0981 × 23.74 × 10^-3

= 0.00233 mole.

Molar concentration of acid = 0.00233/25 × 10^-3

= 0.093 M.

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.