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Introduction about laboratory techniques
General laboratory techniques 1
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Chemistry: Acid-Base Titration Purpose: The objective of this experiment were: a) to review the concept of simple acid-base reactions; b) to review the stoichiometric calculations involved in chemical reactions; c) to review the basic lab procedure of a titration and introduce the student to the concept of a primary standard and the process of standardization; d) to review the calculations involving chemical solutions; e) to help the student improve his/her lab technique. Theory: Titration was used to study acid-base neutralization reaction quantitatively. In acid-base titration experiment, a solution of accurately KHP concentration was added gradually to another solution of NaOH concentration until the chemical reaction between the two solutions were completed. The equivalence point was the point at which the acid was completely reacted with or neutralized by the base. The point was signaled by a changing of color of an indicator that had been added to the acid solution. Indicator was substance that had distinctly different colors in acidic and basic media. Phenolphthalein was a common indicator which was colorless in acidic and neutral solutions, but reddish pink was result in basic solutions. Strong acid (contained H+ ion) and strong base ( contained OH ) were 100% ionized in water and they were all strong electrolytes. Procedure: Part A. Investigating solid NaOH for use as a possible primary standard First o...
taken into account. It is also best to make sure you are working in a
20.0cm3 of 0.10M ethanoic acid was pipetted into a conical flask. 3. 0.10M sodium hydroxide solution was titrated using phenolphthalein as indicator, until the solution was just turned pink. 4. A further 20.0cm3 of the same ethanoic acid solution was added to the flask and was mixed thoroughly.
We were then to make a base solution of 0.7 M NaOH. In order to standardize
The equation shows how 1 mol of Na2CO3 reacts with 1 mol of H2SO4, so
...for the original titration, shown in Table 5. This could be due to perhaps usage of the wrong indicator, or of not stopping the titration exactly when the color changed.
The same procedure was done using 10ml of CV and 20ml of sodium hydroxide, both separately diluted to 50ml and added in a large beaker. The absorbance was recorded. In the last trial, 10ml of CV, 10ml of NaOH were diluted to 50ml. Before adding the two mixtures, 1ml of soap was added to the NaOH solution and then poured into a large beaker, along with the CV. Absorbance was recorded and the materials
Acid-Base balance is the state of equilibrium between proton donors and proton acceptors in the buffering system of the blood that is maintained at approximately pH 7.35 to 7.45 under normal conditions in arterial blood. It is important to regulate chemical balance or homeostasis of body fluids. Acidity or alkalinity has to be regulated. An acid is a substance that lets out hydrogen ions in solution. Strong acid like hydrochloric acid release all or nearly all their hydrogen ions and weak acids like carbonic acid release some hydrogen ions.
1. The key factor I plan to investigate and what I will do to make my
Some improvements to the experiment might be using Na Acetate or Na Citrate as buffers instead of KHPO4. The pH ranges are 4.5-5.5 and 4.7-5.5, respectively. This range falls closer to the ideal pH of 5, then KHPO4 (pH
the left so that the concentration of H is more than Me and so the
Add 15mL of 6N sulfuric acid to a 125mL Erlenmeyer flask containing 105mL of deionized water (preparing approximately 0.75N sulfuric acid). Obtain a sample of the unknown. Weight the vial and contents accurately on an analytical balance. Handle the vial with a small strip of paper to reduce the risk of error (due to added weight). Pour about half of the sample into a clean dry 200mL Erlenmeyer flask and weight again. Use the remaining half of the sample to get a second weight of around 0.6g-0.7g. Make sure the vial is capped on every weight taken.
The simplest experiment for this type of situation would be to use red and blue litmus paper to distinguish between acids, bases and salts. Hydrochloric acid (HCl) makes blue litmus paper change color going from blue to red, making it an acid. Sodium hydroxide (NaOH) makes red litmus paper change color going from red to blue, making it a base. Sodium chloride solution (NaCl) is neutral, since it would only soak blue and red litmus paper, considering that it is a by product of when an acid and a base mix together, neutralizing each other.
Titration is a technological process in which a solution, known as a titrant, is slowly and carefully added from a burrette into a fixed volume of another solution (known as the sample). In an acid-base titration an acid neutralizes a base or vice versa. This process is maintained untill the reaction between the titrant and the sample (acid and the base) is judged to be complete. The reaction is judged to be complete when the endpoint is reached. An endpoint in a titration analysis is referred to as the point at which no more titrant is added due to an observable colour change of an indicator. Indicators can be used to find an endpoint because they change colour when the pH of a solution changes and an endpoint in a titration is an empirical approximation of the equivalence point, which is the point of major pH change in the titration sample due to the fact that equal chemical amounts of reactants have been combined at that point. All indicators have a pH range, which is the range of pH values at which the colour of the indicator changes. Thus
borate) and 1.0 g. of sodium hydroxide in 20 mL of warm water. It may
In this experiment the Sodium Hydroxide solution went through three different phases where its quality and quantity changed. The first phase was called I. Preparing Approximately 0.1M NaOH, 1000mL of clear distilled water was boiled and then chilled to room temp.