SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN

Moderators: Chem_Mod, Chem_Admin

Henri_de_Guzman_3L
Posts: 88
Joined: Fri Sep 28, 2018 12:25 am

SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN

Postby Henri_de_Guzman_3L » Fri Dec 07, 2018 1:28 am

Does anyone know if Dr. Lavelle gave instructions on doing sig figs in pH calculations? Apparently there is a special rule in chemistry. Each decimal place AFTER the decimal pointcounts as one sig fig. Everything to the LEFT of the decimal point does not count as a sig fig.

For example: 7.3 has one sig fig, 12.96 has 2 sig figs, 4.789 has 3 sig figs and so on.
Here's some links for more information:

http://abacus.bates.edu/acad/depts/biobook/How-SigF.pdf
https://www.chemteam.info/AcidBase/pH&sig-figs.html
https://www.adriandingleschemistrypages.com/ap/ph-and-sig-figs/
https://www.youtube.com/watch?v=yvCPFuWhaLQ

So will we be tested using these special rules?

Chase Yonamine 1J
Posts: 62
Joined: Fri Sep 28, 2018 12:17 am

Re: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN

Postby Chase Yonamine 1J » Fri Dec 07, 2018 1:33 am

Yes, I believe sig figs count only after the decimal point. For example, if the molarity .0023 is given the correct answer with sig figs is Ph=2.64 because the sig figs only count after the decimal point.

Henri_de_Guzman_3L
Posts: 88
Joined: Fri Sep 28, 2018 12:25 am

Re: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN

Postby Henri_de_Guzman_3L » Fri Dec 07, 2018 1:34 am

Did Dr. Lavelle mention this in class?

Brandon Mo 4K
Posts: 70
Joined: Fri Sep 28, 2018 12:15 am

Re: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN

Postby Brandon Mo 4K » Fri Dec 07, 2018 2:59 am

He did not mention it in class, but I think it is mentioned on the significant figures pdf on his class website.

Hedi Zappacosta 1E
Posts: 66
Joined: Fri Sep 28, 2018 12:27 am

Re: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN

Postby Hedi Zappacosta 1E » Fri Dec 07, 2018 9:28 pm

Also, if you are calculating the reverse like 10^1.558, then the answer would be 36.1 because you only use how many sig figs are after the decimal in the exponent

Henri_de_Guzman_3L
Posts: 88
Joined: Fri Sep 28, 2018 12:25 am

Re: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN

Postby Henri_de_Guzman_3L » Sat Dec 08, 2018 3:49 pm

Thank you everyone! Good luck on the final


Return to “Calculating pH or pOH for Strong & Weak Acids & Bases”

Who is online

Users browsing this forum: No registered users and 2 guests