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### Rounding atomic weight (general question)

Posted: Sun Apr 08, 2018 5:11 pm
I noticed when Prof. Lavelle is calculating molar mass of compounds (or anything involving math), he writes the mass of O as 16 g.mol-1, but H stays 1.008 g.mol-1. Is there a guideline we should follow when rounding atomic masses?

### Re: Rounding atomic weight (general question)  [ENDORSED]

Posted: Sun Apr 08, 2018 5:30 pm
In the test we will be given a periodic table and I would assume that we are meant to use whatever version of the atomic mass that the table specifies :)

### Re: Rounding atomic weight (general question)

Posted: Sun Apr 08, 2018 9:13 pm
Yeah I would say always use the maximum number of digits given to you in the question or periodic table on the assessment, and then round according to significant figures only at the very end of the problem.

### Re: Rounding atomic weight (general question)

Posted: Sun Apr 15, 2018 9:37 pm
Personally, I would use whatever is given in the question or periodic table and not round until the very end, just to make my calculations as accurate as possible

### Re: Rounding atomic weight (general question)

Posted: Sun Apr 15, 2018 10:28 pm
Personally, I just follow the periodic table, no matter how tedious it may be to spell out the entire number, just to be safe. You could just save the rounding for the end, while also attaching a solution that isn't rounded possibly.

### Re: Rounding atomic weight (general question)

Posted: Sun Apr 15, 2018 10:33 pm
I think that best thing to do is to just follow the periodic table, that way you can't be wrong. Also it save time while performing in the exams.

### Re: Rounding atomic weight (general question)

Posted: Sun Apr 22, 2018 4:06 pm
I also struggled with different periodic tables having different values present, but I just asked my TA if I could keep the periodic table from the quiz week 2 and have been using that one and it corresponds well.

### Re: Rounding atomic weight (general question)

Posted: Sun Apr 22, 2018 5:50 pm
I would just use the periodic table atomic masses. I usually round when finding amount in moles to have a whole number

### Re: Rounding atomic weight (general question)

Posted: Sun Apr 22, 2018 7:26 pm
I would use the atomic mass on the periodic table he gives us, and round at the end.