Answer:
20 equivalents of sulfuric acid are needed to per equivalent of lidocaine.
Explanation:
To do this calculation we should take in account the key information given:
2 mL (0.02 L) of sulfuric acid (H2SO4) 2.2 M per 1 g of lidocaine (molecular weight=234.34 g/mol)
So we can calculate from here the number of moles of each compound needed for the procedure.
Starting with the sulfuric acid, we know that the molar concentration is defined as [concentration] =n(moles number)/V(volume).
So n=[concentration]*V, and therefore :
n(H2SO4)=2.2 M * 0.02 L=0.044 mol
While the moles of lidocaine can be calculated as n(moles number)=m(mass amount)/mW(molecular weight), so:
n(lidocaine)=m(lidocaine)/mW(lidocaine)= 1 g /234,34 g/mol~0,0043 mol.
Now we can calculate the equivalents.
Take in account that for sulfuric acid, de number of equivalents per mole is 2 (because of the double dissociation of the acid), while the number of equivalents per mole of lidocaine is 1.
Then we can conclude that:
0,0043 equivalents of lidocaine need 0,088 equivalents of sulfuric acid
1 equivalent of lidocaine need (0,088/0.0043)=20,46~20 equivalents of sulfuric acid
Finally, we can conclude that for the described procedure, 20 equivalents of sulfuric acid per equivalent of lidocaine are needed.
