What is the concentration

Question

What is the concentration (in mol L-1) of 12.5 mg of each of disopyramide phosphate and lidocaine hydrochloride dissolved in 250 mL?

Answer 1

molar mass of disopyramide phsohpate = 339 g/mole

molar mass lidocaine HCl = 234 g/mole

For disopyramide phosphate:

12.5 mg x 1 g/1000 mg x 1 mole/339 g = 3.69x10^-5 moles

3.69x10^-5 moles/0.250 L = 1.47x10-4 mole/liter

 

For lidocaine HCl:

12.5 mg x 1 g/1000 mg x 1 mole/234 g = 5.34x10^-5 moles

5.34x10^-5 moles/0.250 L = 2.14x10^-4 moles/liter