Describe making up the EDTA in a solution To dertermine the total hardness in a water sample using EDTA
A known volume of EDTA is made up into a solution using a solid, weighed on an electronic balance… made up to sln in a beaker.. volumetric flask…bottom of the mencisicus rests on the graduation mark.
Key Terms
Describe making up the EDTA in a solution To dertermine the total hardness in a water sample using EDTA
A known volume of EDTA is made up into a solution using a solid, weighed on an electronic balance… made up to sln in a beaker.. volumetric flask…bo...
describe filling the burette with the EDTA solution To dertermine the total hardness in a water sample using EDTA
Clap burette upright … fill the edta above the 0cm mark and then let the liquid slowly drain out of the tap until the bottom of the menciscus rests...
Describe transferring an excact solution of hard water into the conical flask. **To dertermine the total hardness in a water sample using EDTA
It is common to transfer a mulitable of 25cm of hard water… transfer the known volume of water into a breaker.
What is in the beaker before the titration occours? What colour is in the titration before the reaction begins
To dertermine the total hardness in a water sample using EDTA
pH buffer solution 10 Erichrome Black T indicator a RED-WINE colour forms in the conical flask in the presence of Ca2+/Mg2+ ions.
State and explain the colour change at the end point
To dertermine the total hardness in a water sample using EDTA
The colour turns from red-wine to blue the presence of Ca2+/Mg2+ ions to the absence of Ca2+/Mg2+ ions.
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| Term | Definition |
|---|---|
Describe making up the EDTA in a solution To dertermine the total hardness in a water sample using EDTA | A known volume of EDTA is made up into a solution using a solid, weighed on an electronic balance… made up to sln in a beaker.. volumetric flask…bottom of the mencisicus rests on the graduation mark. |
describe filling the burette with the EDTA solution To dertermine the total hardness in a water sample using EDTA | Clap burette upright … fill the edta above the 0cm mark and then let the liquid slowly drain out of the tap until the bottom of the menciscus rests on the graduation mark. |
Describe transferring an excact solution of hard water into the conical flask. **To dertermine the total hardness in a water sample using EDTA | It is common to transfer a mulitable of 25cm of hard water… transfer the known volume of water into a breaker. |
What is in the beaker before the titration occours? What colour is in the titration before the reaction begins To dertermine the total hardness in a water sample using EDTA | pH buffer solution 10 Erichrome Black T indicator a RED-WINE colour forms in the conical flask in the presence of Ca2+/Mg2+ ions. |
Name and justify the indicator used for determining the total hardness in a water sample using EDTA. | Erichrome Black T (sometime called solochrome black) Erichrome Black T is a red-wine colour in the presence of Ca2+/Mg2+ ions Erichrome Black T turns blue in the absence of Ca2+/Mg2+. |
State and explain the colour change at the end point To dertermine the total hardness in a water sample using EDTA | The colour turns from red-wine to blue the presence of Ca2+/Mg2+ ions to the absence of Ca2+/Mg2+ ions. |
What is hard water?What is the cause of hard water? To dertermine the total hardness in a water sample using EDTA | Hard water is water that will not easily form a lather with soap. Hard water is caused by the presence of Ca2+ /Mg2+ ions. |
what is meant by tempoary hardness? In what compound are Ca2+ and Mg2+ ions in tempoary hard water present To dertermine the total hardness in a water sample using EDTA | Ca(HCO3)2 - calcium hydrogencarbonate. |
What is meant by permanent hardness? In what compound are Ca2+ and Mg2+ ions in permanent hard water present To dertermine the total hardness in a water sample using EDTA | Permanent hardness is hardness that cannot be removed by boiling water caused by CaSO4. |
Explain the term total hardness To dertermine the total hardness in a water sample using EDTA | The sum of permanent hardness and temporary hardness. |
suggest a way of dertimining if a sample of water contained tempoary hardness and how the concentration of tempoary hardness could be achieved To dertermine the total hardness in a water sample using EDTA | Titrate the water sample against edta and find the value for hardness(total hardness). Boil the water to remove temporary hardness. Titrate the boiled water sample against EDTA and find the value for hardness.(Permanent hardness only). |
What is the full name of the EDTA reagent To dertermine the total hardness in a water sample using EDTA | Ethylenediaminetetraacetic acid. |
Why is a standard solution of EDTA used in this titration To dertermine the total hardness in a water sample using EDTA | EDTA reacts with metal ions and forms an EDTA-metal complex. During this titration, it will react with the Ca2+/Mg2+ ions in the hard water to use them up. The end point is the moment where all the Ca2+/Mg2+ ions are used up. |
why is EDTA stored in a plastic container To dertermine the total hardness in a water sample using EDTA | EDTA reacts with the metal ions in glass. |
What are buffer solutions To dertermine the total hardness in a water sample using EDTA | Solutions that resist changes to pH and keeps the Ph of an environment at a desired value. |
Why is pH buffer 10 required for this titration? To dertermine the total hardness in a water sample using EDTA | A pH of 10 is needed for EDTA to react with the Ca2+/Mg2+ ions and form an edta metal complex. The Erichrome black T indicator changes colour only at a pH of 8-10. An inaccurate end point will be obtained at a pH other than 10. |
Describe how to make up the sodium thiosulfate into solution Measure the amount of dissolved oxygen in a sample of water by redox | Weigh sodium thiosulfate on electronic balance, wash into beaker stir with stirring rod in beaker of deionied water… transfer into a volumetric flask. |
describe filling the burette with sodium thiosulfate solution Measure the amount of dissolved oxygen in a sample of water by redox | Clamp retort stand with burette upright, fill above the 0cm mark and let drain until the bottom of the mencisus rests on the 0cm mark. |
Describe making a solution of iodine using the dissolved oxygen in the water sample NB Measure the amount of dissolved oxygen in a sample of water by redox | An clean empty dry reagent bottle is rinsed with deionised water and the water it will contain. The bottle is full submerged into the water sample and completely filled a dropper is used to add 1cm of Mangenses (II) sulfate (MnSo4) and Alkaline potassium iodide (KOH) snd (KI) the reagent bottle is carefully stoppered and shaken unil a Brown percipitate is observed Concentrated Sulfuric acid (H2SO4). |
Overall, 1mol of O2… Measure the amount of dissolved oxygen in a sample of water by redox | …liberates 2 mols of I2. |