### Planck Constant

Posted:

**Wed Oct 11, 2017 7:48 pm**In the lecture we are given Plancks constant as 6.626x10^34 but in the module it is rounded to 6.63x10^-34, should we round or keep 4 sig figs?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=14&t=22080

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Posted: **Wed Oct 11, 2017 7:48 pm**

In the lecture we are given Plancks constant as 6.626x10^34 but in the module it is rounded to 6.63x10^-34, should we round or keep 4 sig figs?

Posted: **Wed Oct 11, 2017 8:00 pm**

From I remember Lavelle said that during tests we will be provided with constants so I wouldn't worry to much about whether we should round or use 4 sig figs.

Posted: **Wed Oct 11, 2017 8:27 pm**

just remember that you use the sig figs in the values given (including given constants) for the final answer so just take that into consideration with writing your final answer

Posted: **Thu Oct 12, 2017 12:30 am**

Yeah since you will probably get the value of the constant on the formula sheet, I would just use the value given. Otherwise, just follow the rounding necessary based off the given values.

Posted: **Thu Oct 12, 2017 9:56 am**

Sig figs are mainly important in the final answer, so do not worry about rounding in the middle of a problem. For the final answer, I would determine the number of sig figs based on the number that has the least number sig figs in the original problem.

Posted: **Thu Oct 12, 2017 12:42 pm**

It's probably better to use 6.626x10^-34 just so that your final answer is more accurate and precise, but to be safe, use whatever is given on the formula sheet

Posted: **Thu Oct 12, 2017 4:37 pm**

Sig figs are mostly used in the final answer rather than throughout all of the steps in the equations. Though, it's a good idea to keep 3 or 4 digits after the decimal just so there's greater accuracy in the final answer when rounded.

Posted: **Thu Oct 12, 2017 4:52 pm**

I would say 6.626 x 10^-34 would be best because its precise but Lavelle said they will be given to us on tests.

Posted: **Thu Oct 12, 2017 10:50 pm**

I would definitely use 6.626*10^-34 when doing calculations since it is more precise. If you're concerned about sig figs, just remember that they don't matter so much during the process as they do in your final answer. Use the least number of sig figs in the given values to determine how many you include in your final answer.