Asked by Muneer

Question: A student measured 278.44mL of 0.72M HCl solution into a beaker. How many moles of HCl were in the beaker?

The answer I got was 0.2005 moles. Am I correct?
Answered by DrBob222
Yes. Technically, however, you are allowed only two significant figures. When multiplying numbers you are allowed the the number of s.f. in the least of the s.f. shown in the values multiplied (or divided). So mols = M x L. That is 278.44mL x 0.72M = 0.222476. Since the 0.72 has just two s.f., then you should round your answer to 0.20 moles.
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