Why is oxalic acid a good primary standard for redox reaction AND acid base reactions?
Q. how come in redox titrations the oxalate ion needs to be heated?
Asked by NOYOU - Thu Jul 28 10:19:17 2011 - Chemistry - 1 Answers - Comments

A. Why is oxalic acid a good primary standard for redox reaction AND acid base reactions? a] it has a relatively high molar mass b] crystals can be obtained very pure and are neither hygroscopic or deliquescent formula: C2H2O4.2H2O c] very stable in solid form and not expensive d] as an acid can be used for acid- base reactions, and as readily oxised, also for redox reactions. how come in redox titrations the oxalate ion needs to be heated? It only need to be heated when being titrated with acod permanganate [manganate(VII)]. This is because it has quite a high activation energy, so needs to get to about 60C to get going. After this the reaction speeds up because of autocatalysis... one of the products Mn2+ ions catalyses the reaction, now… [cont.]
Answered by Colin - Thu Jul 28 11:52:48 2011

HI help PLZZ.Calculate the weight in grams of the primary standard solid oxalic acid needed to prepare 250 ml?
Q. Calculate the weight in grams of the primary standard solid oxalic acid needed to prepare 250 ml of a 0.200 N solution to be used in this laboratory exercise.
Asked by vana - Sun Feb 17 12:20:12 2008 - Chemistry - 1 Answers - Comments

A. There will be 0.2 moles of acid in 1 litre of solution. We want 250ml. of solution, therefore we need 0.2 * 0.25 = 0.05 moles of oxalic acid. Assume it is the doubly-hydrated form. Formula = HOOCCOOH.2H2O = C2H6O6 Molecular mass = 12 * 2 + 1 * 6 + 16 * 6 = 24 + 6 + 96 = 126 g/mole so 0.05 moles weighs 0.05 * 126 = 6.3g. We need 6.3g. of oxalic acid dihydrate to prepare 250ml. of a 0.2 mole/litre solution.
Answered by Blue Rizla Girl - Sun Feb 17 12:44:52 2008

What are the properties of an ideal primary standard in titration experiments?
Q.
Asked by jammina - Sun Jul 20 23:54:06 2008 - Chemistry - 1 Answers - Comments

A. There is nothing such as an ideal solution, but I think these can be considered: The titrant should have a reaction with the primary standard, which has distinguishable properties as a chemical. Technical side- the primary standard should be dissolved in accurate volume of water, so as to get a stock solution of known molarity.
Answered by Soham G - Mon Jul 21 09:44:40 2008

Is potassium iodate a primary standard ?
Q. Is potassium iodate a primary standard ?
Asked by ask_knowledge - Sun Oct 8 05:42:03 2006 - Chemistry - 3 Answers - Comments

A. Potassium Iodate is an oxidizing agent and a good primary standard with the one drawback of having a relatively low equivalent weight. It is used primarily as a stable source of Iodine, which is liberated in the presence of Iodide ion and acid, in the titration of Thiosulfate and Sulfite solutions.
Answered by tekn33k - Sun Oct 8 05:51:26 2006

three requirements for a chemical to be considered for use as a primary standard.?
Q. List and explain the importance of the three requirements. Thanks!
Asked by dchiu85 - Mon Jul 7 15:25:26 2008 - Chemistry - 2 Answers - Comments

A. it's 100% pure and anidrous it has to be not higly hygroscopic it has to be light insensitive it has to be termically stable
Answered by dvstudio 08 - Thu Jul 10 05:27:23 2008

Briefly explain Why a hygroscopic compound would be a poor primary standard?
Q.
Asked by tee-z - Sun Oct 4 22:51:13 2009 - Chemistry - 1 Answers - Comments

A. Firstly lets start with what a primary standard is (well i assume you already have an idea but just to make sure we are on common grounds) Usually they are used for titrations to find an exact concentration of a certain reagent (acid or base solution). Hence, they are a reference standard for further calculations to be accurate (and also precise) So, it is important to know the exact mass of the primary standard and hence make a known concentration solution of it. But if the primary standard is hygroscopic (meaning it takes up water and absorbs water), then its very difficult to know its exact mass as when you are weighing it, it may not be the primary standard itself, it may have water molecules attached to it, hence obscuring the mass.… [cont.]
Answered by Double C Double H - Sun Oct 4 23:07:43 2009

Mass and volume data for titration of primary standard acid and unknown acid with sodium hydroxide?
Q.
Asked by Gabriella - Tue Oct 14 21:21:30 2008 - Chemistry - 1 Answers - Comments

A. part A Run 1 Mass of weighing paper 0.4452 Mass of weighing paper and H2C2O4*2H2O 0.6812 Initial reading of buret (m L) 0 Final reading of buret (m L) 32.00 Questions Part A questions Run1 Mass of H2C2O4*2H2O used (g) 0.6812 - 0.4452 = 0.2360 grams Moles of H2C2O4*2H2O (mol) 0.2360 grams @ 126.07 g/mol = 0.001872 moles acid Number of protons available for reaction OH- 2 H+ / molecule acid Moles of OH- which reacted *Mol) @ 2 Na OH & 1 H2C2O4 --> 0.001872 moles acid => twice => 0.003744 moles Na OH Volume of Na OH solution used (m L) 32.00 ml Molarity of Na OH solution (M) 0.003744 moles Na OH / 0.03200 litres = 0.1170 Molar Na OH Average molarity of Na OH (M) you will need to plug the other two trialls through & use the… [cont.]
Answered by Steve O - Tue Oct 14 23:55:01 2008

Suppose a sodium hydroxide solution were to be standardized against pure solid primary standard grade KHP. If ?
Q. 0.4538 g of KHP requres 44.12 m L of the sodium hydroxide to reach a phenophthalein endpoint, what is the molarity of the Na OH solution? Thanks soo much for the help (in advanced)!
Asked by Audrey W - Mon Oct 20 23:39:18 2008 - Chemistry - 1 Answers - Comments

A. well the equation for the molarity of Na OH solution for this information would be ... weight of KHP/ (molar weight of KHP)x(volume of Na OH) ***the molar mass for KHP is 204.22 grams/ mol ***also don't forget to change 44.12 ml to .04412 L ...so you would have (0.4538g KHP) / (204.22 grams/mol KHP) x (.04412 L Na OH) = .0504 M of Na OH
Answered by Heliosword - Mon Oct 20 23:54:34 2008

Why is hydrochloric acid not suitable as a primary standard ?
Q. just come across the question in my homework and I couldn't answer it. Please help ! Thanks in advanced
Asked by Ice Ice - Wed Jun 11 05:26:12 2008 - Chemistry - 1 Answers - Comments

A. foremost because it is volatile, so it is hard to keep its concentration very precise even when you make this standard
Answered by Anatol - Wed Jun 11 05:48:45 2008

Why is sodium oxalate used a primary standard in redox titrations?
Q.
Asked by moses m - Tue Nov 18 09:23:28 2008 - Chemistry - 1 Answers - Comments

A. A standard solution of sodium oxalate can be prepared by direct weighing of sodium oxalate. So it is used as a primary standard.
Answered by trikha - Tue Nov 18 09:32:18 2008

why is it a waste of time to weigh out accurately a primary standard of doutbful purity?
Q. it is a chemistry lab question..please help me =(
Asked by - Fri Aug 21 04:09:41 2009 - Chemistry - 1 Answers - Comments

A. Lets say the standard has a 99.99% purity, and you carefully wiegh out a 1000 grammes, that means 1 gramme is something unknown and therefore could affect the results If you don't even know what level of purity the standard has how can you accurately measure against it Remember you are using a standard to measure something else against, if you don't know what the standard is you don't know what you are measuring, imagine a ruler with some numbers missing around where you want to measure - you could only ever guess a result So you need to know the purity of a standard - it does not need to be pure, but as long as you know you can adjust your numbers accordingly
Answered by Intrepid - Fri Aug 21 04:22:26 2009

What is the most convenient primary standard for the determination of Na OH concentrations and why is it used?
Q.
Asked by chem88 - Tue Oct 31 14:57:04 2006 - Chemistry - 3 Answers - Comments

A. This depends on which level you are working at (GCSE, A level or higher). To get an accurate standard the acid being titrated against the Na OH should have a high relative molecular mass which will make errors in its weighing less. It should also be stable. For work up to GCSE sulphuric acid is suitable but for more accurate determination potassium hydrogen phthalate is used with phenolphthalein as the indicator.
Answered by Examiner - Wed Nov 1 15:51:49 2006

Can oxalic acid be used as a primary standard to standardise a basic solution, such as sodium hydroxide?
Q. Thanks.
Asked by Purple Monkey Dishwasher - Sat May 16 03:23:45 2009 - Chemistry - 3 Answers - Comments

A. I checked through a list of recommended primary standards, which must meet a very high set of requirements to be so classified. Oxalic acid is not included in this list. This could be due to a number of reasons, such as for instance, hygroscopicity, indefinite end point among others.I do not know the exact reason. Here are the requirements of a good primary standard: A primary standard in chemistry is a reliable, readily quantified substance. Features of a primary standard include: 1. High purity 2. Stability (low reactivity) 3. Low hygroscopicity and efflorescence 4. High solubility (if used in titration) 5. High equivalent weight 6. It should be nontoxic 7. It should be readily available (inexpensive) 8. It should be environmentally… [cont.]
Answered by Trevor H - Sat May 16 03:59:42 2009

Good primary standard for standardizing Na OH?
Q. Just checking if someone knows a good primary standard to use for this and at what PH they would neutralize/ the equivalence point? Thanks! 0.1M of the primary standard with roughly 0.1M Na OH
Asked by maths d - Thu Jul 15 08:43:18 2010 - Chemistry - 1 Answers - Comments

A. The most common primary standard for neytralising Na OH is KHP = potassium hydrogen phthalate. You do not prepare a solution of the primary standard , but you accurately weigh out a knowm mass of KHP, dissolve in water and titrate the whole against the Na OH. The molar mass of KHP is 204.2212 g/mol. If you want to standardise 0.1M Na OH, where the titration result will be about 25ml - that is a convenient volume - you will need to weigh out 0.5 grams of KHP. Use phenolphthalein indicator, KHP is a weak acid and Na OH a strong base. KHP and Na OH react 1:1 molar To clarify: Accurately weigh out about 0.5g KHP = say you weigh out 0.5218g. Dissolve in water in erlenmeyer flask Titrate the whole against the unknown Na OH solution - say volume… [cont.]
Answered by Trevor H - Thu Jul 15 14:00:00 2010

What is the possibility of using Na OH as primary standard?
Q.
Asked by jammina - Sun Jul 20 23:51:03 2008 - Chemistry - 1 Answers - Comments

A. You mean for a titration? Can't do it. Solid Na OH contains an unknown amount of water, so you can't measure it accurately by mass. Na OH solutions absorbe CO2 from the air, so the solutions don't retain a constant concentration.
Answered by Robinson Cruz - Mon Jul 21 01:54:12 2008

What is the difference between Standard solution and Primary standard solution & secondary standard solution?
Q. I very confused to try to differentiate between them. another question during my reading in the interent it said Na-OH not primary so why is this as my tutor in the university during the experiment said to us that Na-OH the titrant we have is primary as it was 0.1 N Na-OH
Asked by sali - Fri Jul 16 09:30:52 2010 - Chemistry - 1 Answers - Comments

A. The term "primary standard" is used for compounds that are extremely pure and stable with no water of hydration. Read through the link to see what the term means in more detail. Na OH can be standardized using a primary standard but is chemically reactive and will pick up water and CO2 from the atmosphere over time. Its reactivity with water is rapid and occurs while weighing out the pure Na OH, making its assay uncertain. The primary standard used for Na OH is potassium hydrogen phthalate, KHP. This makes Na OH a secondary standard at best. Your tutor is mistaken in this case. Be gentle. Hope this helps.
Answered by Robert D - Fri Jul 16 11:12:33 2010

Can oxalic acid be used as a primary standard for ACID-BASE titrations?
Q. I know that oxalic acid is a suitable primary standard for REDOX titrations, but is there any reason it can't be used as a primary standard for acid-base titrations?
Asked by Curious Sam - Tue Jul 17 07:51:28 2007 - Chemistry - 1 Answers - Comments

A. A primary standard is some substance such as oxalic acid which can be precisely weighed out in pure form, so that the number of moles present can be accurately determined from the measured weight and the known molar mass. For example, we might prepare a 0.1000 molar solution of primary standard oxalic acid by weighing out exactly 0.1 moles of oxalic acid and diluting to one litre in a volumetric flask. The standard solutions used in an acid-base titration need not always be primary standards. A standard solution which has been prepared by quantitative dilution of a primary standard is an excellent secondary standard solution. Secondary standards can also be prepared by titration against a primary standard solution...
Answered by Dr.Shashikant - Tue Jul 17 08:23:23 2007

Calculating an approximate Na OH concentration and preparing a primary standard of benzoic acid.?
Q. 1. An Na OH solution was prepared by dissolving approximately 4g of solid Na OH in 200 m L of water. Calculate and record the approximate Na OH concentration (MW = 40.00). 2. To prepare the primary standard, first calculate and record the expected mass of benzoic acid required to react in stoichiometric proportion with 20 m L of the Na OH solution (MW = 122.12). Record this amount.
Asked by Missy - Sun Apr 20 15:34:32 2008 - Chemistry - 1 Answers - Comments

A. Hi - this is not as hard as it looks - here's how you figure it out: 1. Na OH has a molecular weight of 40 (as you said), so 4 g is 1/10 of a mole (or 0.1 mol). Having this much Na OH in 200 m L (or .2 L) of water makes the concentration (.1) / (.2) = 1/2 mol/L (or 0.5 M) [M is for molar - the measure of molarity.] 2. Now, in stoichiometric proportion, 2 mol of Na OH are require for every 1 mol of benzoic acid (C6H5COOH), so we need (2 x .1 mol) = .2 mol. At a molecular weight of 122.12, that means we need 24.424g of benzoic acid. See the link below for more about benzoic acid and it's reactions (the only challenging part of this). Hope this helps!
Answered by opus23 - Mon Apr 21 18:43:53 2008

Which is true for a primary standard acid or primary standard base?
Q. Which of the following is true for a primary standard acid or a primary standard base? 1) It reacts according to one invariable reaction 2) Does not react with the atmosphere (especially CO2 and H2O in the atmosphere) 3) Must have atleast two ionizable hydrogen ions or hydroxide ions 4) Has a very high formula weight 5) It is very deliquescent 6) It produces a colored solution 7) It is soluble in water
Asked by Cherokee Rose - Fri Jan 16 23:04:43 2009 - Chemistry - 2 Answers - Comments

A. According to JExam it's 1, 2, 4, and 7 :)
Answered by Nick - Tue Jan 20 21:02:10 2009

Na OH solution were to be standardized against pure solid primary standard grade KHP?
Q. If 0.4538g of KHP requires 44.12m L of the Na OH to reach a phthalein endpoint, what is the molarity of the Na OH solution?
Asked by Zer0 - Mon Jun 30 16:20:55 2008 - Chemistry - 1 Answers - Comments

A. 44.12 can go to grams since 1g in 1 ml...44.12 g * 1mol/ 39.9971g= 1.10308 mol...i dunno if this helps, but its a start! hehe
Answered by karmelcoloredprincess47 - Mon Jun 30 16:40:30 2008