Question

i have data, Acid is HCl and base is NaOH

△H=mC_h2o(T_i-T_f)

i am looking for the mass(m) please explain this..

Vacid	Vbase	Cacid	Cbase	Ti	Tf
50 mL	50 mL	1.0 M	1.0 M	22.4 C	30.4 C

Answer 1

Solution:

Volume in mL amd Concentration in M is given in the data, so mass can be calculated by using Molarity formulae,

Molarity = Moles / Volume in Litres { Moles = Mass / Molecular. weight}

Molecular weight of HCl = 36.5 and NaOH = 40

Mass of HCl is calculated by,

1.0 M = (Mass / 36.5) / 0.05

i.e., Mass of HCl = (1.0 *36.5) * 0.05 = 1.825 gram

Similarly for mass of NaOH is calculated by,

1.0 M = (Mass / 40) / 0.05

i.e., Mass of NaOH = (1.0*40) *0.05 = 2 grams

While calculating del H the mass of both HCl and NaOH have to be added to (1.825 + 2 = 3.825 gm) as both reactant combines to form product, so the m term in equation is m = 3.825 gm and C_water = 4.186 @ STP,        T_f = 30.4 C, T_i = 22.4 C

By substituting all the calculated values in equation gives,

Note : I took C value of water in J/gm C as the required is not mentioned in question the solution is given in standard unit.