Are all pH calculations done to 2 decimal places or do we use sig figs in pH calculations?  [ENDORSED]

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

Are all pH calculations done to 2 decimal places or do we use sig figs in pH calculations?

Postby Henri_de_Guzman_3L » Fri Dec 07, 2018 1:23 am

For example 6B.5c in the 7th edition textbook asks us to calculate the pH for 0.0092 M Ba(OH)2. This is 2 sig figs but the answer in the back gives 12.96. Should the answer instead be 13?

anthony_trieu2L
Posts: 60
Joined: Fri Sep 28, 2018 12:29 am

Re: Are all pH calculations done to 2 decimal places or do we use sig figs in pH calculations?  [ENDORSED]

Postby anthony_trieu2L » Fri Dec 07, 2018 1:32 am

For pH calculations, the sig figs are only accounted for after the decimal point. In this case, since there are two sig figs in 0.0092 M Ba(OH)2, the final answer should present two digits after the decimal point. Thus, 12.96 is correct.

RandallNeeDis3K
Posts: 34
Joined: Fri Sep 28, 2018 12:25 am

Re: Are all pH calculations done to 2 decimal places or do we use sig figs in pH calculations?

Postby RandallNeeDis3K » Fri Dec 07, 2018 1:45 am

pH calculations only follow sig figs after the decimal point! so two sig figs after the decimal point makes sense.


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