How to convert PPB to molarity?

Chemistry and homework help forum.

Organic Chemistry, Analytical Chemistry, Biochemistry, Physical Chemistry, Computational Chemistry, Theoretical Chemistry, High School Chemistry, Colledge Chemistry and University Chemistry Forum.

Share your chemistry ideas, discuss chemical problems, ask for help with scientific chemistry questions, inspire others by your chemistry vision!

Please feel free to start a scientific chemistry discussion here!

Discuss chemistry homework problems with experts!

Ask for help with chemical questions and help others with your chemistry knowledge!

Moderators: expert, ChenBeier, Xen

Post Reply
User avatar
Dhamnekar Winod
Sr. Staff Member
Sr. Staff Member
Posts: 149
Joined: Sat Nov 21, 2020 10:14 am
Location: Mumbai[Bombay],Maharashtra State,India

How to convert PPB to molarity?

Post by Dhamnekar Winod »

If any water reserve has lead concentration of 20 ppb, how is that = 1 × 10⁻⁷ M Pb²⁺.

My attempt: 20 ppb=x L/1 L solution → x= 20 × 10⁻⁹ L

Now density of

Pb²⁺=11.34 g/cm³ → 20ppb =1.09 × 10⁻⁶ M Pb

Where i am wrong?
Last edited by Dhamnekar Winod on Mon Apr 19, 2021 9:48 am, edited 2 times in total.
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
User avatar
ChenBeier
Distinguished Member
Distinguished Member
Posts: 743
Joined: Wed Sep 27, 2017 7:25 am
Location: Berlin, Germany

Re: How to covert PPB to molarity?

Post by ChenBeier »

20 ppb = 20 mikrogramm/kg = 2*10^-5 g /kg / 207 g/ mol = 0,096 mikromol/kg= 9,66 * 10^-8 mol/kg ~ 1*10^-7 mol/l

For what you need density. It is an aquaeous solution and not solid lead.
User avatar
Dhamnekar Winod
Sr. Staff Member
Sr. Staff Member
Posts: 149
Joined: Sat Nov 21, 2020 10:14 am
Location: Mumbai[Bombay],Maharashtra State,India

Re: How to convert PPB to molarity?

Post by Dhamnekar Winod »

But mol/Kg and mol/liter are inconsistent units. How did you make unit conversion?
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
User avatar
ChenBeier
Distinguished Member
Distinguished Member
Posts: 743
Joined: Wed Sep 27, 2017 7:25 am
Location: Berlin, Germany

Re: How to convert PPB to molarity?

Post by ChenBeier »

There is no. %, ppm, ppb are parts of a mass unit. For volume you can estimate because 20 ppb is at least nothing. The solution is like water.
User avatar
Dhamnekar Winod
Sr. Staff Member
Sr. Staff Member
Posts: 149
Joined: Sat Nov 21, 2020 10:14 am
Location: Mumbai[Bombay],Maharashtra State,India

Re: How to convert PPB to molarity?

Post by Dhamnekar Winod »

So, my answer is also correct which is 1.09e-6 M/l. This solution is also like a water
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
User avatar
ChenBeier
Distinguished Member
Distinguished Member
Posts: 743
Joined: Wed Sep 27, 2017 7:25 am
Location: Berlin, Germany

Re: How to convert PPB to molarity?

Post by ChenBeier »

No, you have a error of factor 10. The unit is also wrong what is M/l in your opinion.
M is mol/l. Not mol/ l^2.
User avatar
Dhamnekar Winod
Sr. Staff Member
Sr. Staff Member
Posts: 149
Joined: Sat Nov 21, 2020 10:14 am
Location: Mumbai[Bombay],Maharashtra State,India

Re: How to convert PPB to molarity?

Post by Dhamnekar Winod »

Thanks for your guidance. After doing some chemistry work i got the correct answer. 20 ppb =0.2e-7 l = 0.2e-7 kg = 0.2e-7 × 10³ g=200.0 e-7 g ~ 1.0 e-7 M
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
Post Reply