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A primary standard is usually a solid reactant that:

(1) is available in a high purity form

(2) does not change chemically when stored or exposed to air

(3) has a high formula weight to minimize errors in weighing

(4) is soluble in the solvent being used.

Sodium carbonate, Na 2 CO 3 size 12{ ital "Na" rSub { size 8{2} } ital "CO" rSub { size 8{3} } } {} , is commonly used as a primary standard base for standardizing acids, while potassium acid phthalate (KHP), KHC 8 H 4 O 4 size 12{ ital "KHC" rSub { size 8{8} } H rSub { size 8{4} } O rSub { size 8{4} } } {} , and oxalic acid dihydrate, H 2 C 2 O 4 2H 2 O size 12{H rSub { size 8{2} } C rSub { size 8{2} } O rSub { size 8{4} } cdot 2H rSub { size 8{2} } O} {} , are primary standard acids used for standardizing bases.

Na 2 CO 3 ( s ) + 2 HCl H 2 O + CO 2 + 2 NaCl size 12{ ital "Na" rSub { size 8{2} } ital "CO" rSub { size 8{3} } \( s \) +2 ital "HCl" rightarrow H rSub { size 8{2} } O+ ital "CO" rSub { size 8{2} } +2 ital "NaCl"} {} (4)

KHC 8 H 4 O 4 ( s ) + NaOH KNaC 8 H 4 O 4 + H 2 O size 12{ ital "KHC" rSub { size 8{8} } H rSub { size 8{4} } O rSub { size 8{4} } \( s \) + ital "NaOH" rightarrow ital "KNaC" rSub { size 8{8} } H rSub { size 8{4} } O rSub { size 8{4} } +H rSub { size 8{2} } O} {} (5)

( COOH ) 2 2H 2 O ( s ) + 2 NaOH Na 2 ( COO ) 2 + 4H 2 O size 12{ \( ital "COOH" \) rSub { size 8{2} } cdot 2H rSub { size 8{2} } O \( s \) +2 ital "NaOH" rightarrow ital "Na" rSub { size 8{2} } \( ital "COO" \) rSub { size 8{2} } +4H rSub { size 8{2} } O} {} (6)

The dry solid is carefully weighed on an analytical balance and then diluted in a volumetric flask to give a known molarity. The molarity of an acid or base is determined by titrating a measured volume of the acid or base with the primary standard. Then these acid or base solutions can in turn be used to determine the molarity of another acid or base (this is the case with the standardized solutions of NaOH and HCl used in this experiment).

In the example below a known amount of KHP will be titrated with a solution of NaOH to determine the NaOH solution concentration.

EXAMPLE: If 0.8168 g of KHP requires 39.35 mL of NaOH to reach the endpoint in a titration, what is the molarity of the NaOH? (1 mol KHP = 204.2 g)

0 . 8168 gKHP × 1 molKHP 204 . 2 gKHP 1 molNaOH 1 molKHP 1 39 . 35 mLNaOH 1000 mL 1L = 0 . 1016 mol / L = 0 . 1016 M size 12{0 "." "8168" ital "gKHP" times left ( { {1 ital "molKHP"} over {"204" "." 2 ital "gKHP"} } right ) left ( { {1 ital "molNaOH"} over {1 ital "molKHP"} } right ) left ( { {1} over {"39" "." "35" ital "mLNaOH"} } right ) left ( { {"1000" ital "mL"} over {1L} } right )=0 "." "1016" ital "mol"/L=0 "." "1016"M} {}

Notes on titration method:

1. Clean the buret until it drains smoothly.

2. Make sure the stopcock doesn't leak. The level should hold for ~3 minutes.

3. Remove air bubbles from buret tip before beginning. Rapid spurts usually work.

4. Rinse the buret two or three times with 5 mL portions of titrant (the solution you will use to titrate). Hold it horizontal and rotate to rinse.

5. Don't forget to record the initial reading. It does not need to be 0.00 mL.

6. Use a reading card to find the bottom of the meniscus.

7. Always read and record buret volumes to 0.01 mL.

8. Remember that the buret scale reads down, not up.

9. Put white paper under the flask to see color change easily.

10. Swirl the flask with one hand while turning the stopcock with the other or use stir bar and stir plate.

11. Add titrant slowly near the endpoint. Color that dissipates can be seen when getting close to endpoint.

12. Drops can be "split" by quickly turning the stopcock through the open position.

13. Near the endpoint use deionized water from wash bottle to rinse the flask walls from any splashed drops (adding water does not affect number of moles you have).

14. Don't drain buret below 25 mL (You won’t be able to determine final volume accurately). If necessary, read the buret level, refill, read the level, and continue. 

Calculation clarification

Amount neutralized by antacid 25ml of HCLThe amount of HCl that was neutralized by the fragment of the whole tablet, was only neutralized in part, this is where the titration comes in, the solution was still acidic, even after the dissolved antacid fragment, so the volume of NaOH used to finally cause the change in color is equal to the excess of HCl that was in the solution of HCl + water + antacid. So the number of moles of NaOH that was used is equal to the number of moles of HCl that was neutralized by the NaOH. So we DO use the formula in the procedure, so in the report form, where it had asked for the number of moles of HCl neutralized by the antacid:

n HC ln eutralizedbyAntacid = n HCladded n HClexcess size 12{n rSub { size 8{ ital "HC""ln" ital "eutralizedbyAntacid"} } =n rSub { size 8{ ital "HCladded"} } - n rSub { size 8{ ital "HClexcess"} } } {}

So then, this would be the 2 . 5 × 10 3 size 12{2 "." 5 times "10" rSup { size 8{ - 3} } } {} mol HCl–the excess which is calculated by converting the volume of NaOH used into moles, this number of moles then equals the number of moles oh HCl.

Volume NaOH titratedvolume excess HCl = volume titration of NaOH

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
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Source:  OpenStax, Honors chemistry spring. OpenStax CNX. Mar 10, 2008 Download for free at http://cnx.org/content/col10512/1.9
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