How can I find the concentration given that PH=3.15 of an acid? And that the temperature is 25degrees c

2 Answers
Apr 7, 2018

Use the definition of #pH#?

Explanation:

#pH=-log_10[H_3O^+]#...and then take antilogs..

#pH=3.15#...and thus #[H_3O^+]=10^(-3.15)*mol*L^-1#..

#[H_3O^+]=7.08xx10^-4*mol*L^-1#...note that we found concentration with respect to #[H_3O^+]#...we have NO handle on the concentration of the parent acid #[HX]#...which might have been strong #[HX]=[H_3O^+]# or WEAK...#[HA]">>"[H_3O^+]#. We assume here that the acid is strong.

Apr 7, 2018

#7.08*10^-4 \ "M"#

Explanation:

We have the #"pH"# equation, which states that,

#"pH"=-log[H^+]#

  • #[H^+]# is the hydrogen ion concentration in terms of molarity.

And so, we got:

#3.15=-log[H^+]#

#[H^+]=10^-3.15#

#~~7.08*10^-4 \ "M"#