You carry out the titration of a weak diprotic solid acid. You take 178.0 mg of the solid acid and dissolve it in about 50 mL of distilled water. You titrate with 0.095 M NaOH and arrive at an endpoint at 25.20 ml. You know that at the final pH both protons have been titrated. What is the formula weight (molar mass) of the acid?

Explanation:

Equation of the reaction:

H2X(aq) + 2NaOH(aq) --> Na2X + 2H2O

Mass of acid = 0.178 g

Number of moles = molar concentration * volume

= 0.095 * 25.20 mL⋅1 L/1000 mL

= 0.00239 mol

From the equation of reaction,

2 moles of NaOH neutralises in 1 mole of H2X.

Therefore,

0.00239 mole of NaOH, number of koles of H2X = 2 * 0.00239 mol

= 0.0012 mole.

Molar mass = mass/number of moles

= 0.178/0.0012

= 148.7 g/mol.

i just learnt this recently but i need to look through my notes again

> b takes place in the gas phase in an isothermal tubular reactor. the feed is one mole of a per one mole of c, an inert. the entering temperature and pressure are 427°c and 10 atm, respectively. the gas constant r = 0.08206 atm · l/mol · k.