# Converting units and sig figs (finding molarity)?

This may seem very basic, but I'm a little confused.

"What is the molarity of a solution 500 mL of which contains 0.500 moles of HCl?"

Being that 500 has one significant figure, would it be 500 mL = 0.5 L as opposed to 500 mL = 0.500 L? In which case the answer would be 1 mol/L instead of 1.00 mol/L?

• 500 ml and 0.500 moles corresponds to 1.00 mol/l solution. The next decimal place is uncertain, i.e after the second zero. Jun 14, 2017 at 16:07

In terms of significant figures, you always use the number with least amount of sig figs to determine how many sig figs your answer has. In this case, one number has 3 sig figs, and the other has 1. Therefore your answer should have 1 sig fig and be 1 mol/L, as you said. To make the zeroes in the 500 mL become significant it would need to have a period afterwards like this: 500. mL. Perhaps the writer forgot to do that, however as it is written the answer would be 1 sig fig: 1 mol/L

• I didn't realize it was you again :P No problem, hope it helped! Jun 13, 2017 at 21:28
• By the way, on this forum, if someone successfully answered your question, you can press the check mark underneath the upvote and downvote arrows to indicate your question has been answered. That way it will be visible that this question has a correct answer. Jun 13, 2017 at 21:30