Question

If I need 30-mmol of a 1M BH₃/THF solution for a reaction, how do I figure out how many mL's of that solution I need without knowing the density of the solution?

Answer 1

Hi,

If you know the concentration of the solution which is 1M (1 mol / L, this means that there is one mole of BH3 / THF for each liter of solution) and also the required moles (30mmol), then to know the volume only The following relationship is made.
Before, it is necessary to do the conversion of mmol to mol, as shown:
 30 mmol * (1mol/1000mmol) = 0.03 mol

When knowing the moles it is posed: if in a liter of solution there is 1 mol, in 0.03 mol how many liters are there?
  1mol -------- 1L solution
0.03 mol ------ X
X = 0.03mol * (1L Solution / 1mol)
 
The moles are simplified:
L Solution = 0.03 L

When converted to mL:

mL solution = 0.03L * (1mL / 1000L)

Liters are simplified and finally the required mL for 0.03 moles is obtained:
mL solution = 0.00003 mL

If you liked the resolution, it would help me a lot. Thank you very much and greetings