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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Sis290025 on October 18, 2005, 05:24:37 PM

Title: Molarity and Chemical Equations
Post by: Sis290025 on October 18, 2005, 05:24:37 PM

A. Determine the total number of moles of solid sodium hydroxide required to react with 486.00mL of 0.8000M phosphoric acid (H3PO4).

Did I set up the equation correctly?
3NaOH + H3PO4 --> Na3PO4 + 3H20

Then, mol H3PO4(3mol NaOH/1mol H3PO4) = mol NaOH, where mol H3PO4 = (0.8000M)(0.486L)?

B. Determine the concentration of 232.7mL of lead nitrate, Pb(NO3)2 if the sample reacts exactly with 241.0mL of 0.391M potassium iodide (KI).


Equation: Pb(N03)2 + 2KI --> PbI2 + 2KNO3??

so mol PB(NO3)2 = 0.391 M KI *(.241 L KI) (1 mol Pb(NO3)2/ 2 mol KI)

Thanks. Please reply.

Title: Re:Molarity and Chemical Equations
Post by: Borek on October 18, 2005, 06:08:53 PM

Equations looks OK. Show final results and I will tell you if they are OK.

Title: Re:Molarity and Chemical Equations
Post by: Sis290025 on October 18, 2005, 06:20:29 PM

a. 1.17 mol NaOH

b. 0.0471 M Pb(NO3)2

(from set-up)

Thanks.

Title: Re:Molarity and Chemical Equations
Post by: Borek on October 18, 2005, 06:52:31 PM

Quote from: Sis290025 on October 18, 2005, 06:20:29 PM

a. 1.17 mol NaOH

OK

Quote

b. 0.0471 M Pb(NO3)2

Wrong. You forgot one step of calculations.

Title: Re:Molarity and Chemical Equations
Post by: Sis290025 on October 18, 2005, 07:21:01 PM

For B, that was the mol of Pb(NO3)2.   :o

For M, 0.0471 mol Pb(NO3)2/ .2327 L Pb(NO3)2 = 0.202 M .

Must remember to read question! *ties bow to thumb*  :-[

Thanks.

Title: Re:Molarity and Chemical Equations
Post by: Borek on October 19, 2005, 05:15:11 AM

Kim - look here:

http://www.chemicalforums.com/index.php?board=2;action=display;threadid=5381 (http://www.chemicalforums.com/index.php?board=2;action=display;threadid=5381)

Title: Re:Molarity and Chemical Equations
Post by: Sis290025 on October 19, 2005, 06:50:50 AM

Who's Kim?  ???

Title: Re:Molarity and Chemical Equations
Post by: Borek on October 19, 2005, 07:08:13 AM

Author of the moved post.