Titration Experiment - URGENT (1 Viewer)

[sgsupremacy]

Hey, I'm having a hard time understanding titration, I know that you have to make your own solution so that you know the volume and concentration, but whats primary standard? In this prac we were told to make a solution of
Na<SUB>2</SUB>CO<SUB>3, then titrate with HCI, then titrate HCI with NaOH..</SUB>
<SUB></SUB>
<SUB>The task description is,</SUB>
<SUB>Determine the concentration of a solution of sodium hydroxide by titration with approximately 0.1M hydrochloric acid. This solution of hydrochloric acid must first be standardised to determine its accurate concentration.</SUB>
Any help would be greatly appreciated. Thank You in advance!!
<SUB></SUB>

 

[me121]

i think there was another thread just like this.. umm.. firstly i suggest you read my notes on a titration prac that i had to do, http://www.boredofstudies.org/download.php?id=9531
try reading that.. i can't really remember enough to answer your question, but i think the answer is in that link.

 

[WantToDoBetter]

Hey, I'm having a hard time understanding titration, I know that you have to make your own solution so that you know the volume and concentration, but whats primary standard? In this prac we were told to make a solution of
Na<SUB>2</SUB>CO<SUB>3, then titrate with HCI, then titrate HCI with NaOH..</SUB>
<SUB></SUB>
<SUB>The task description is,</SUB>
<SUB>Determine the concentration of a solution of sodium hydroxide by titration with approximately 0.1M hydrochloric acid. This solution of hydrochloric acid must first be standardised to determine its accurate concentration.</SUB>
Any help would be greatly appreciated. Thank You in advance!!
<SUB></SUB>

I'm stretching my memory so correct me if im wrong.

For what i remember a primary standard solution is a solution made by yourself when you know the exact mass of the solid (Na2CO3 in your case) and the exact mass of the water need to give you a solution of a certain molarity.

When making the solution you need to be very perdantic, washing when you can as to but dilute or contaminate your solution.

Once that primary standard solution is made (using calculations- i cant remember, ask your teacher) you can use it to test the molarity of your unknown (HCl). Once the molarity of the HCl is known, you can titrate it with your unknown NaOH to find it's molarity!

I think that's it! Good luck, i hope it heaps.
Cheers champion!

 

[brenton1987]

but whats primary standard?

Primary standards need to be at least 99.9% pure, stable under ordinary storage and stable when dried by heat or vacuum to remove traces of water.

They are used to accurately determine the concentration of another solution. In your example, hydrochloric acid is produced by dissolving HCl gas in water, its concentration is a best guess until it is tested with a standard. NaOH is hygroscopic so weighing errors are present because of absorbed water. A direct titration of HCl and NaOH will be full of errors.

A sodium carbonate standard is made by heating the pure powder to over 100^oC but less than 800^oC to drive off the water while preventing decomposition to carbon dioxide and sodium oxide. A sample is weighed and dissolved in water and the concentration is known accurately.