[confusedcollegestudent]

The problem says:
Calculate the number of moles of NaBH₄ in 1.5 mL of NaBH₄ solution, if there are 80 mg of NaBH₄ per milliliter of solution used?
How would I start or set up this problem??

[XeLa.]

Firstly, identify the meaning of molarity, and work from there.

[Babcock_Hall]

What do you need to convert from mass (typically in grams) to amount (typically in moles), or vice versa?

[P]

All good advice  -  you break it down to first principles...  count the atoms! :-)

[CSteps]

Convert the mg to g first. it is 0.08 g.

Then you can do it by the following conversion:

moles of NaBH₄ = 1.5 mL x 0.08 g/1 mL x 1 mol NaBH₄/37.8 g

In the first step, we find how many grams of NaBH4 we have and in the second, we convert it to the mass using the molar mass of NaBH4 which is 37.8 g/mol.