Penicillin ( MM = 356 g / mol ) , an antibiotic often used to treat bacterial infections, is a weak acid. Its K a is 1.7 × 10 − 3 . Calculate [H + ] in solutions prepared by adding enough water to the following to make 725 mL. (a) 0.187 mol (b) 127 g
Penicillin ( MM = 356 g / mol ) , an antibiotic often used to treat bacterial infections, is a weak acid. Its K a is 1.7 × 10 − 3 . Calculate [H + ] in solutions prepared by adding enough water to the following to make 725 mL. (a) 0.187 mol (b) 127 g
Penicillin
(
MM
=
356
g
/
mol
)
, an antibiotic often used to treat bacterial infections, is a weak acid. Its Ka is
1.7
×
10
−
3
. Calculate [H+] in solutions prepared by adding enough water to the following to make 725 mL.
(a) 0.187 mol
(b) 127 g
Expert Solution
Interpretation Introduction
(a)
Interpretation:
The concentration of hydrogen ion in the given solution should be calculated.
Concept introduction:
The dissociation reaction of a weak acid is represented as follows:
HB⇄H++B−
The expression for the acid dissociation constant will be as follows:
Ka=[H+][B−][HB]
Here, [H+] is equilibrium concentration of hydrogen ion, [B−] is equilibrium concentration of conjugate base and [HB] is the equilibrium concentration of weak acid.
Answer to Problem 52QAP
0.020 M
Explanation of Solution
The acid dissociation constant of penicillin is 1.7×10−3. The volume of solution is 725 mL and number of moles of the acid is 0.187 mol.
The molarity of penicillin can be calculated as follows:
M=nV(L)
Putting the values,
M=0.187 mol725 mL(10−3 L1 mL)=0.258 M
Thus, the concentration of penicillin is 0.258 M.
The molecular formula of penicillin is C16H18N2O4S.
The concentration all the species can be calculated using the ICE table as follows:
Since, the value of x cannot be negative thus, the value of x will be 0.020.
From the ICE table, it is equal to the concentration of hydrogen ion thus,
[H+]=0.020
Therefore, the concentration of hydrogen ion is 0.020 M.
Expert Solution
Interpretation Introduction
(b)
Interpretation:
The concentration of hydrogen ion in the given solution should be calculated.
Concept introduction:
The dissociation reaction of a weak acid is represented as follows:
HB⇄H++B−
The expression for the acid dissociation constant will be as follows:
Ka=[H+][B−][HB]
Here, [H+] is equilibrium concentration of hydrogen ion, [B−] is equilibrium concentration of conjugate base and [HB] is the equilibrium concentration of weak acid.
Answer to Problem 52QAP
0.02805 M
Explanation of Solution
The mass of penicillin is given as 127 g. The molecular formula of the penicillin is C16H18N2O4S thus, its molar mass is 356 g/mol.
Now, from mass and molar mass of the C16H18N2O4S, its number of moles can be calculated as follows:
n=mM=127 g356 g/mol=0.3567 mol
Now, the molarity of C16H18N2O4S can be calculated as follows:
M=nV(L)
Putting the values,
M=0.3567 mol725 mL(10−3 L1 mL)=0.492 M
Thus, the concentration of C16H18N2O4S is 0.492 M.
The concentration all the species can be calculated using the ICE table as follows:
"Water gas" is an industrial fuel composed of a mixture of carbon monoxide and hydrogen gases. When this
fuel is burned, carbon dioxide and water result. From the information given below, write a balanced equation
and determine the enthalpy of this reaction:
CO(g) + O2(g) → CO₂(g) + 282.8 kJ
H2(g) + O2(g) → H₂O(g) + 241.8 kJ
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4. Calculate AG for the following reaction at 25°C. Will the reaction occur (be spontaneous)? How do you
know?
NH3(g) + HCl(g) → NH4Cl(s)
AH=-176.0 kJ
AS-284.8 J-K-1
true or false
The equilibrium constant for this reaction is 0.20.
N2O4(g) ⇔ 2NO2(g)
Based on the above, the equilibrium constant for the following reaction is 5.
4NO2(g) ⇔ 2N2O4(g)
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