Which of the following molecules acts as a Lewis acid ?
(CH3)3B
(CH3)2O
(CH3)3P
(CH3)3N
The rapid change of pH near the stoichiometric point of an acid base titration is the basis of indicator detection. pH of the solution is related to ratio of the concentrations of the conjugate acid (HIn) and base (In-) forms of the indicator given by the expression
log [In-] / [HIn] = pKIn-pH
log [HIn] / [In-] = pKIn-pH
log [HIn] / [In-] = pH-pKIn
log [In-] / [HIn] = pH -pKIn
Calculate the pOH of a solution at 250C that contains 1.0×10-6 M of hydronium ions .
7.00
4.00
9.00
1.00
Ionisation constant of CH3COOH is 1.7×10-5 and concentration of H+ ions is 3.4×10-4. Then, find out initial concentration of CH3COOH molecules.
3.4 × 10-4
3.4 × 10-3
6.8 × 10-4
6.8 × 10-3
The pH value of a 10 m solution of HCl is _________ .
less than 0
Equal to 0
Equal to 1
Equal to 2
The solubility product of a sparingly soluble salt AX2 is 3.2 ×10-11. Its solubility ( in mol / L ) is _____ .
5.6 ×10-6
3.1 ×10-4
2 ×10-4
4 ×10-4
0.1 M solution of which one of these substances will be basic ?
Sodium borate
Calcium nitrate
NH4Cl
Sodium sulphate
A Physician wishes to prepare a buffer solution at pH =3.58 that efficiently resist changes in pH yet contains only small concentration of the buffering agents. Which one of the following weak acid together with its sodium salt would be best to use ?
m-chlorobenzoic acid (pKa=3.98)
P-Chlorocinnamic acid(pKa = 4.41)
2,5 -dihydroxy benzoic acid (pKa=2.97)
Acetoacetic acid(pKa=3.58)
The hydride ion H- is strong base than its hydroxide ion OH-. Which of the following reactions will occur if sodium hydride (NaH) is dissolved in Water ?
2H-(aq) + H2O(l)→H2O+H2 +2e-
H-(aq) + H2O(l)→OH-+H2
H - + H2O(l) → no reaction
None of the above
Which of the following statements about pH and H+ ion concentration is incorrect ?
addition of one drop of concentrated HCl in NH4OH solution decreases pH of the solution.
A solution of the mixture of one equivalent of each of CH3COOH and NaOH has a pH of 7 .
pH of pure neutral water is not zero .
A cold and con.H2SO4 has lower H+ ion concentration than a dilute solution of H2SO4
