Titration of Acids and Bases One of the most common reactsont in chemistry is th

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Titration of Acids and Bases One of the most common reactsont in chemistry is the reaction of an acid with a base, which is often ed a neutralization reaction in th volumetric method ofanalys be studied by concentration of titration, These techniques will be applied to the deterniination of the reaction of a sodium hydroxide solution and the molar concentration of hydrochloric acid The ne for au acid-base titration is Hydrochlorie ucid will be titrated with a sodium hydroxide solution to determine its concentration. In order to perform this titration. the molaaity ofthe needed. Since NaoH is usually impure, it impossible to prepare an accurately known concentration of a NaoH solution by measuring the mass of sodium hydroxide words, primary standard. The the NaoH ill be determined by a method called standardization using a very pure sample of potassium hydrogen phthalate for KHP). KHCsHaoa, KHP is a good primary standard for standardizing base known mass of KHP is dissolved in distilled water and the NaOH solution will be added to exactly accurately the The volume of the base wil measured using a The technique of measuring the of a solution required to react with another teagent is called titration. An indicator solution is necessary to determine when the base has exactly neutralized the acid, or vice versa. The best indicator will change when are present, which is referred to as the equivalence point in titratior difficulito ini an beiwii change colors exactly at the equivalence point, sinee the eolor c hange does not exactly optrespond e equivalence point, the color change is called the end point or the point at which the addition ofthe reagent is stopped. Indicators must be selected so the difference between the endpoint and equivalence is a small as possible. In this experiment is the indicator, which is pink colored in a basic solution (color change occurs around pH 9) and colorless in an acidic solution, The balanced equation for the neutralization of KHP with NaOH is shown belo If the mass of KHP is known, the moles of KHP may be found using the molar mass of KHCiHwos. A the equivalence point an equal llumber of moles of KHP and NaoH are present. Since the moles of NaoH and the volume of NaoH used to reach the end point are known, the nolarity of the NaoH may standard NaOH solution. be determined. This solution is now referred to as a Once the molarity of the NaGHis known, the base can be used to determine the amount of an acid present. In this experiment the molarity of hydrochloric acid will be determined by performing the reaction shown The laboratory experiment is being performed to determine the molarities sodium hydroxide and hydrochloric acid solutioas which will be used in a future experiment to measure the heat of formation of magnesium oxide. The heat formation of magnesium oxide is a calorime experiment and will require the calorimeter constant from the specific heat experiment and the molarity

Explanation / Answer

One of the use of titration is to standardize acids using known concentration of primary standard alkalis. Here KHP trial readings are taken for NaoH as its never pure primary standard and then with known volume of HCl titrated with standard base, concentration of acid can be found.

2. Any errors in method or so will result in a big margin gap of trial readings which only1percent is permissible. Adding Naoh or any analyte vigorously to flask, Air bubbles in burrete, leaking of analyte from burrete ..amongst other reasons.

3. To detect equivalence point accurately proper volumes of both titrant and analyte should be taken and known.

4. One reason being for higher concentration of analyte more of titrant Will be used. also at high conc some chemicals are harmful to handle. Also more no of titrations can performed with dilutions. And too much high conc can alter PH calculations if indicators behave differently at higher concentrations sometimes.

5. A primary standard concentration is known. It's constant at all times, so errors due to mass are reduced. Low reactivity. High purity. Non toxic.

6. KHP contaminated with NaCl will reduce the H+ , thus less than actual base trial readings will be observed. But that depends on how much contamination is present.

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