rounding of the elements.  [ENDORSED]

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rounding of the elements.

Postby SarahSteffen_LEC4 » Wed Oct 02, 2019 3:45 pm

So when I normally solve homework problems involving the molar mass of elements of compounds, I use all of the numbers given for each element (without rounding initially) to solve for a problem. But in the solution manual, sometimes I will get a different answer that is only off by a few decimal points, which I assume is with how the rounding was done initially. Is it fine that I am not also getting the exact answer as the solution manual down to the decimal point or no? Any help would be greatly appreciated with this.

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Re: rounding of the elements.  [ENDORSED]

Postby sarahsalama2E » Wed Oct 02, 2019 3:50 pm

Personally, I use the entire values that I get from my calculator in each step of the problem until I get to the final step, then when I get there I round/determine the correct number of sig figs that I need at the end. I do it this way just to make sure I am exact as possible, or as much as I can be.

Gerald Bernal1I
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Re: rounding of the elements.

Postby Gerald Bernal1I » Wed Oct 02, 2019 3:50 pm

I'm sure if you are off by a few decimal points ypu should be okay. If anything look at the solutions manual to see what numbers and sig figs they are using to get their answer. It may not be just from not rounding the atomic mass, but maybe from other factors in your calculations or how you are inputting it in your calculator.

Adam Kramer 1A
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Re: rounding of the elements.

Postby Adam Kramer 1A » Wed Oct 02, 2019 5:01 pm

I typically round the elements about 2 or 3 decimals, as that typically matches the sig figs in the problem, and they usually are only off by about a few thousandths or so, which my TA has said is not a really big deal when they are grading out answers.

Claire Stoecklein 1E
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Re: rounding of the elements.

Postby Claire Stoecklein 1E » Wed Oct 02, 2019 5:35 pm

Final answers should typically have 3 sig figs, which means all values throughout the calculations should be 4 or 5 sig figs to avoid rounding numbers.

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Re: rounding of the elements.

Postby zoedfinch1K » Wed Oct 02, 2019 5:52 pm

Personally, I save rounding as the very last step and make sure to use the appropriate amount of sig figs according to the question. As Claire said, make sure you are using 4-5 decimal points when doing your calculations to be as precise as possible. I'm sure that as long as the steps to get to your answer are correct, it shouldn't matter that you are only off by a few decimal points.

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Re: rounding of the elements.

Postby Sjeffrey_1C » Wed Oct 02, 2019 6:11 pm

To add, all periodic tables round to different decimal positions. Therefore, it ca't be expected that everyone gets the exact same answers unless there is one singular periodic table we were told to use. This isn't the case though, right?

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