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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: confusedcollegestudent on July 10, 2017, 09:09:49 PM

Title: Molarity and unit conversions.
Post by: confusedcollegestudent on July 10, 2017, 09:09:49 PM

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??

Title: Re: Molarity and unit conversions.
Post by: XeLa. on July 10, 2017, 09:19:07 PM

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

Title: Re: Molarity and unit conversions.
Post by: Babcock_Hall on July 11, 2017, 10:29:21 AM

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

Title: Re: Molarity and unit conversions.
Post by: P on July 12, 2017, 06:49:25 AM

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

Title: Re: Molarity and unit conversions.
Post by: CSteps on August 27, 2017, 03:02:52 PM

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.