|
Title: Question looking for hydroxide ion concentration? Post by: polishprodigy93 on May 30, 2019 The [OH-] of a solution of 3.41 mol/L sodium carbonate is ? in mol/L?
Title: Re: Question looking for hydroxide ion concentration? Post by: 7.prime7105 on May 31, 2019 Sodium carbonate is a weak acid, so it incompletely disassociates:
Na2CO3 + 2 H2O > H2CO3 + 2 NaOH If [Na2CO3] = 3.41 mol/L, multiply it by 1 L to get the number of moles = 3.41. It's a 1 to 2 ratio between Na2CO3 and NaOH, so multiply that by 2 = 6.82 moles of NaOH. Divide by 1 L and you have the concentration of OH. Title: Re: Question looking for hydroxide ion concentration? Post by: bio_man on May 31, 2019 Content hidden
Title: Re: Question looking for hydroxide ion concentration? Post by: polishprodigy93 on May 31, 2019 Where did you get 2.1 x 10^-4 as the Kb value for CO32-? I look at the chart in my book but I don't see that value anywhere or am I missing something?
Title: Re: Question looking for hydroxide ion concentration? Post by: bio_man on May 31, 2019 I found it online, what does your textbook give as the value? Take a picture if possible and upload it
Title: Re: Question looking for hydroxide ion concentration? Post by: polishprodigy93 on May 31, 2019 Pages 8 and 9 are the charts we refer too
Title: Re: Question looking for hydroxide ion concentration? Post by: bio_man on May 31, 2019 According to the chart provided, it has a ka of 4.7 × 10–11. Since this is a base, we need to change this to kb using the formula:
kw = ka × kb Where kw = 1.0 × 10-14 So: 1.0 × 10-14 / 4.7 × 10–11 = This is why it was used in the calculation... :yelling: Please mark as solved if content with the answer. |