Tartaric acid, C4H6O6, has the first ionization constant with the value: Ka1 = 9.20 × 10-4. Calculate the value of pKb for the conjugate base of tartaric acid. 10.963 3.036 1.087 x 10-11 9.20 x 10-4

pKb = 10.96

Explanation:

Tartaric acid is a dyprotic acid. It reacts to water like this:

H₂Tart  +  H₂O  ⇄  H₃O⁺   +  HTart⁻         Ka1

HTart⁻  +  H₂O  ⇄  H₃O⁺   +  Tart⁻²           Ka2

When we anaylse the base, we have

Tart⁻²   +  H₂O  ⇄  OH⁻  +  HTart⁻       Kb1

HTart⁻  +  H₂O  ⇄  OH⁻  +    H₂Tart          Kb2

Remember that Ka1 . Kb2  = Kw, plus pKa1 + pKb2 = 14

Kb2 = Kw / Ka1  →   1×10⁻¹⁴ / 9.20×10⁻⁴  = 1.08×10⁻¹¹

so pKb = - log Kb2   → - log 1.08×10⁻¹¹ = 10.96  

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

> 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.