Calculate the ph of the solutions obtained by mixing:

a) 50.0 cm3 of 0.25 m ch3cooh and 62.5 cm3 of 0.20 m nach3coo

b) 40.0 cm3 of 0.5 m nh4oh and60 cm3 of 1.0 m nh4cl

c) v cm3 of 0.1 m nah2po4 and 3v cm3 of 0.1 m na2hpo4 (it is actually v not a typo)

ka (ch3cooh) = 1.73 x 10^-5 ; kb (nh3) = 1.8 x 10^-5 ; ka2 (h3po4) = 6.2 x 10^-8

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.