CHM256 GRAVIMETRY ANALYSIS ( CHICKEN STOCK )

[00:00:03]Real chicken, authentic spices, fresh vegetables, all in one cube.

[00:00:10]Maggi chicken stock, packed with flavor, created from nature.

[00:00:16]>> We all know this humble chicken cube. It is a staple in our kitchen, packed with intense savory flavor. But from a chemist's perspective, this cube is a complex of proteins, fat, and a very specific target analyte, which is sodium chloride and common salt.

[00:00:35]How much salt is actually hidden in this concentrated cube? And how can we measure it precisely down to the milligram without relying on the labels?

[00:00:45]And in this presentation, we will explore how we take this everyday food item, dissolve it, and use precipitation gravimetry to physically separate, isolate, and weigh the exact amount of salt it contains.

[00:01:01]>> Assalamualaikum warahmatullahi wabarakatuh. Today, our group are going to present about determination of salt NaCl in a chicken stock gravimetric analysis.

[00:01:11]For theory, the foundation of our experiment is precipitation gravimetry.

[00:01:17]This involves separating an analyte from a liquid sample by converting it into an insoluble solid, which is then weighed to calculate its original concentration.

[00:01:27]For the chemical reaction, when silver nitrate AgNO3 is added to the chicken stock, it reacts with the dissolved sodium chloride NaCl in a double displacement reaction.

[00:01:39]The silver ions Ag+ bond with the chloride ion Cl- to form a white insoluble precipitate of silver chloride AgCl.

[00:01:49]Let us take a look at the diagram. So, inside the chicken stock, the salt NaCl is completely dissolved into a free-moving which is an A+ and Cl- ion ion. When we add the silver nitrate, it releases silver ions as A+ into the stock solution.

[00:02:07]Because silver has an extremely high affinity for chloride, they instantly bind together upon collection.

[00:02:14]This forms a solid network called an AgCl lattice, which appears as a dense, white precipitate.

[00:02:21]Since it's completely insoluble, we can easily filter dry and wet the solid to calculate the exact salt content.

[00:02:31]Next, we'll talk about the chemical equation. AgNO3 + NaCl becomes AgCl + NaNO3.

[00:02:39]For the key precipitation, which is the key principles, first one we have the stoichiometry because the reaction occurs in 1 over 1 molar ratio. The number of moles of AgCl recovered is equal to the moles of Cl- originally in the chicken stock.

[00:02:56]Digestion and purification. Heating the solution allows the colloidal AgCl particles to coagulate into filterable aggregates, which are then washed with dilute nitric acid, HNO3, to prevent peptization and remove matrix interferences like fats and proteins.

[00:03:14]Third, quantification. By measuring the final constant mass of the dry precipitate, we use the gravimetric factor, the ratio of the molar mass of NaCl to AgCl, which is 0.4078, to mathematically determine the precise amount of salt in the sample.

[00:03:38]>> Now, let's walk through the experimental procedure, which begin with sample preparation and precipitation.

[00:03:44]First, for sample preparation, we accurately weigh out 10 g of our chicken stock sample using the analytical balance. We then completely dissolved the sample in approximately 100 ml of distilled water within a beaker to free the chloride ion into the solution.

[00:04:02]Second, we move to the precipitation of chloride. Before adding our main reagent, we add few drops of dilute nitric acid. This create an acidic environment that prevent interference from other potential ion such as carbonate or phosphate. Once acidified, we slowly add our silver nitrate solution while stirring. We keep adding it until we observe that no more white precipitate is forming, ensuring all chloride ion have successfully reacted.

[00:04:32]Once the reaction is complete, we move on to digestion and filtration to isolate our analyte. In step three, digestion, we gently warm the mixture around 60° and let it sit for about 30 minutes. This thermal process allow the tiny colloidal silver chloride particle to coagulate and come together into larger, heavier aggregates that easily settle at the bottom. Next is step four, filtration. We pass the mixture through a pre-weighed filter paper to capture our solid precipitate. To ensure it is completely pure, we wash the trapped precipitate with small portion of cold distilled water. We continue this washing process until the filtrate test completely free of excess nitrate ion, which we verify using diphenylamine or litmus test.

[00:05:21]The final phase of our procedure involve drying, weighing, and quantitative analysis. In step five, drying, the wet AgCl precipitate is placed inside a drying oven set to approximately inside a desiccator.

[00:05:35]We keep it there until a constant mass is achieved, ensuring all residual water is completely driven off.

[00:05:43]For step six, weighing, we allow the crucible and the dry AgCl to cool down completely inside a desiccator so it doesn't reabsorb ambient moisture. Then we take its mass on the balance and subtract the initial tare weight of the empty filter or crucible. This gives us the exact precise net mass of our solid AgCl precipitate.

[00:06:03]Finally, in step seven, the calculation phase, we apply our gravimetric factor of 0.4078 to mathematically convert the mass of the recovered silver chloride back of pure sodium chloride.

[00:06:19]From there, we determine the final percentage of salt present in our original chicken stock.

[00:06:24]Let's take a look at the actual calculation and data.

[00:06:29]>> The calculation of steps to achieve the percentage of NaCl in the chicken stock sample.

[00:06:35]First, we must calculate the gravimetrical factor, which uh we are going to use the formula of molecular weight of Cl over molecular weight of AgCl times mole of Cl over mole of AgCl. As a result, we have got 0.2.5.

[00:06:54]Then next, we must calculate the mass of Cl, which we must use the formula of gravimetrical factor times mass of AgCl, which is the precipitate, 6.17.

[00:07:06]As a result, we got 1.5117 g.

[00:07:11]Next, we must calculate the mole of Cl, which we will use the formula of mass of Cl over relative molar mass of Cl.

[00:07:20]Once you calculate, we will receive 0.0426 mole as the answer.

[00:07:26]Next, we must must use the equation.

[00:07:31]Through the equation, you will you will see that mole of NaCl and mole of Cl is the same. So, 0.0426 mole is a mol of NaCl.

[00:07:44]Once we obtain the mol of NaCl, we must calculate the mass of it.

[00:07:48]So, now we will use the formula of mol of NaCl times molecular weight of NaCl.

[00:07:54]As a result, we got 2.5921 g.

[00:07:58]Lastly, we need to calculate the percentage of NaCl in chicken stock sample.

[00:08:04]We need to use the formula of mass of NaCl over mass of chicken stock sample times 100.

[00:08:11]2.4921 over 10 times 100, we got 24.9% of NaCl in the chicken stock sample.

[00:08:21]>> I'm [clears throat] going to presenting the result and discussion of our gravimetric analysis experiment, where we determine the percentage of sodium chloride or common salt in commercial chicken stock sample.

[00:08:36]The primary objective of this experiment was to isolate and quantify the salt content using precipitation gravimetry from a 10 g sample of chicken stock.

[00:08:51]We successfully precipitated 6.17 g of silver chloride by applying a gravimetric factor of 0.245.

[00:09:03]We determined that our sample contain 1.5117 g of chloride ion, which is translates to 2. 4 921 g of pure sodium chloride.

[00:09:19]Ultimately, this give us experimental salt content of 24.9%.

[00:09:28]For comparison with commercial standard, to understand the accuracy of our result, we compare it to a standard commercial benchmark the Maggi Chicken Stock Cube.

[00:09:39]Based on the nutrition data, a typical 10 g Maggi cube contains about 1.6 g of sodium.

[00:09:46]Through stoichiometric conversion, this equate to theoretical salt content of 26.25%.

[00:09:55]As you can see, our experimental value of 24.9% is noticeably lower.

[00:10:02]This discrepancy suggests that the sample we analyzed might behave a low sodium variant, a different commercial brand altogether, or perhaps a home formulation which is naturally content less concentrated salt than commercial cube.