Worn away statue Mechanical? or Chemical?
2 answers:
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Answer:
of acetic anhydride is needed
Explanation:
According to balanced equation, 1 mol of salicylic acid completely reacts with 1 mol of acetic anhydride
Number of moles = (mass)/(molar mass)
Molar mass of acetic anhydride = 102.09 g/mol
Molar mass of salicylic acid = 138.121 g/mol
So, of salicylic acid =
of salicylic acid
Hence, of salicylic acid reacts completely with
of acetic anhydride.
So, mass of acetic anhydride needed = =
Answer:
a) 129.14 g/mol
b) 8.87
Explanation:
Given that:
mass of the ionic compound [NaA] = 18.08 g
Volume of water = 116.0 mL = 0.116 L
Let the mole of the acid HCl = 0.140 M
Volume of the acid = 500.0 mL = 0.500 L
pH = 4.63
= 1.00 L
Equation for the reaction can be represented as:
From above; 1 mole of an ionic compound reacts with 1 mole of an acid to reach equivalence point = 0.140 M × 1.00 L
= 0.140 mol
Thus, 0.140 mol of HCl neutralize 0.140 mol of ionic compound at equilibrium
Thus, the molar mass of the sample =
= 129.14 g/mol
b) since pH = pKa
Then pKa of HA = 4.63
Ka =
=
= 0.1255 M
of HA =
+
+
Initial 0.1255 0 0
Change - x + x + x
Equilibrium 0.1255 - x x x
As is very small, (o.1255 - x) = 0.1255
[OH⁻] =
But pOH = - log [OH⁻]
= - log []
= 5.13
pH = 14.00 = 5.13
pH = 8.87