Outline
The aim of this experiment is to find the per centum by mass of Ca carbonate. CaCO3 in toothpaste utilizing back titration technique. A known weight part of toothpaste is obtained to respond with known volume and concentration of standard acerb solution. After finishing the reaction. the ensuing solution incorporating extra acid is back titrated with known volume and concentration of standard base solution. Determination of extra acid after reaction allow us to cipher the sum of acerb react with CaCO3 in toothpaste sample. My consequence for this experiment shows that 19. 6 % of Ca carbonate nowadayss in toothpaste sample. In decision. CaCO3 merely made up about one fifth of toothpaste sample. toothpaste derived from a assortment of constituent such as fluoride. H2O and detergent. Since the consequence obtained nearing 20 % . stating that most of the mistake is avoided. the chemical reaction in this experiment is rapid and complete with no side reaction. finding of concentration of reactant is accurate. it is a successful experiment.
Introduction
The intent of this experiment is to better the apprehension of practical application of back titration. Back titration is designed to decide the jobs encountered with forward titration. Back titration can be used for many grounds: when the analyte is volatile or indissoluble in H2O ; when the analyte contains drosss that interfere with forward titration ; when the terminal point is hard to place in forward titration ; when the analyte react easy with titrant in forward titration. In this experiment. a leaden part of toothpaste is analysed to find the per centum by mass of CaCO3 nowadays in the toothpaste sample. Back titration technique is applied in this experiment alternatively of forward titration. This is because the substance being analysed. toothpaste is indissoluble in H2O but soluble in acid.
Theory
Titration is the scientific techinique of volumetric analysis used to find the concentration of unknown solution which involves the direct and bit-by-bit add-on of standard titrant to the analyte until the reaction range neutralisation. Back titration is besides a sort of titration. It is called titration done in contrary because it is non carried out with the solution whose concentration of substance being analysed is required to be known as in the instance of normal titration. In calculating out the concentration of an analyte ( toothpaste. CaCO3 ) . back titration plants by responding the analyte with a known figure of moles of extra intermediate reactant ( hydrochloric acid. HCl ) . The reaction goes past the equality point. The sum of intermediate reactant is in surplus in the reaction with analyte. The resulting mixture incorporating surplus of intermediate reactant is so titrated back with known volume and concentration of titrant ( sodium hydrated oxide. NaOH ) . Knowledge of stoichiometry of the reaction allow the concetration of the analyte in the original solution related to the sum of reagent used.
Procedure
Materials was prepared and equipment was cleaned with distilled H2O if necessary. 10 milliliter of 0. 16M of standard HCl was measured and pipetted into a clean conelike flask. Approximately 0. 1-0. 2g of toothpaste was removed utilizing a glass rod from the container and the exact weight of toothpaste sample was recorded. The glass rod with leaden toothpaste was placed in the conelike flask which contained 10ml of 0. 16M of standard HCl. Toothpaste was dislodged wholly from the glass rod into the conelike flask. About 10ml of deionised H2O was added to rinse down the toothpaste from the glass rod. A funnel was inserted in the flask and the flask was gently heated to boil over a hot home base for 3-5 proceedingss until the reaction was complete. The funnel and the side wall of the flask was rinsed with little sum of deionised H2O. The mixture in the flask was allowed to chill to room temperature. A clean calibrated burette was prepared and the interior of burette was rinsed with NaOH solution.
Rinsing process was repeated. The calibrated burette was filled with extra sum of 0. 08M NaOH solution. Some solution was allowed to run out out through turncock to a waste beaker. The burette was clamped firmly to a retord base. 1-2 beads of methyl orange index was added to conelike flask and it was swirled. The conelike flask was placed under the burette. The initial burette reading was read and recorded. To get down titrating the extra HCl with NaOH. The turncock was opened all the manner and the flask was swirled. As the terminal point was approached. the rate of add-on of HCl into the NaOH was decreased to drop by bead. The terminal point reached when the coloring material of mixture changed from ruddy or tap to orange. The concluding burette reading of NaOH solution was read and recorded. The titration was repeated twice.
