Rendement

Rendement of starch contained in the tubers

In chemistry, the chemical product, the reaction product, or only the rendement refers to the amount of reaction product produced in the chemical reaction. Absolute rendement can be written as weight in grams or in moles (molar yield). The relative results used as the calculation of the effectiveness of the procedure, calculated by dividing the number of products obtained on the mole with theoretical results on the mole: fractional yield = actual results Theoretical yield / initial yield multiplied 100% To obtain Percentage yield, multiply the fraction by 100%. One or more reactants in chemical reactions are often overused. Theoretical rendement is calculated by the number of moles of the limiting reagent. For this calculation, it is usually assumed that there is only one reaction involved. The ideal chemical yield value (theoretical rendement) is 100%, a very unattainable value in practice.

To exemplify the calculation I use the results of the experiment Nober Bumbungan on Wednesday, November 16, 2011.

A.    Methodology

Tools and materials

Tools:

1. The reaction tube                  
2. Blender
3. Stirring rod                                
4. Measuring cups 
5. Oven
6. Grated
7. Glass watch
8. Hot plate
9. Pipette drops
10. Glasses of chemicals
11. Mortar and pestle

Materials :

1. Filter cloth                                
2. Potatoes 
3. Sweet potatoes                      
4. Iodine solution 1%
5. Aquades                                  
6. Corn

       B.     Work Procedure

           a.      Separation of starch

1) Weighing 125 grams that have been smashed with grated.

2) The crushed material is inserted into a 500 ml glass of chemicals and homogenesis by well stirring then filtered with a filter cloth.

3) Filtrates obtained from filtrate are allowed for some time Until the seal settles.

4)  Separates the precipitate and filtrate by decantation.

5) The precipitate obtained is added again with water and stirred, after it is decanted again 3 times.

6) Transferring the precipitate on the glass of the watch previously known to the weigh.

7) The deposits contained on the watch glass Dried in oven at 105 ° C to dry (not sticking to finger).

8)  Weighing the watch glass and calculating the randemen of the starch obtaine.

9)  Calculating the formula with the formula.

   
ket:
a = The sample weight in the material
b = Weight of watch glass 
c = Weight of watch glass containing sediment

b.      Amylum Test

1)      Taking a little precipitate obtained in experiment 1 inserted into the test tube and then added with 2 ml aqades.

2)      Adding a 1% iodine solution is shuffled and observed changes occur.

C. Observation Results 
a.      Separation of starch

No.	Sample	Weight watch glass	Weight of blank watch glass + sediment
1	Cassava	18.4 gr	23,88 gr
2	Potato	18.4 gr	28,9 gr
3	Corn	18.4 gr	26,7 gr
4	Sago	18.4 gr	25,9gr

b.      Amylum Test

No.	Sample	Color	Color after addition of iodine solution
1	Cassava	white	Dark blue
2	Potato	Brown	purple
3	Corn	yellow	purple
4	Sago	Cloudy white	purple

  D.    Data analysis
Formula:

ket:

a = The weight of the sample in the material

b = Weight of blank watch glass

c = The weight of the watch glass contains the sediment 

E. Discussion

Carbohydrates are aldehyde polihydrate compounds which are polymers of monosaccharides with the formula molecule Cn (H2O) n. In carbohydrates are the synthesis of molecules of CO2 and H2O with the help of sunlight and green leaf substances (chlorophyll), known as the synthesis photo process. In this treatment all the material is peeled, crushed and weighed 125 grams, the purpose of which is destroyed by the material to expand the surface plane for easy extraction of the four materials. Then from each of these ingredients are inserted into a 500 ml kimi glass and added with 100 ml of water and well stirred. It is intended to mix and dissolve in water because water is a good solvent for starch because the starch has a hydroxyl group attached to a hydrogen atom of water. Then done the decantation process twice that serves to obtain the essence or starch of each ingredients. The precipitate of the obtained starch was dried by oven at 105 ° C to remove the water content contained in each ingredient. After drying the precipitate of the starch is calculated percent of rendement of each material. Based on the result of calculation from percentage of starch, it was found that the yield of starch was 4.32%, potatoes 8.4%, corn 6.64% and sago 6%. From the results of the calculation of rendemen is not in accordance with the literature, According to (Anonymous, 2011) percent of the yield of starch that is in cassava is 55%, 59.7% potatoes, 59.5% corn and sago 59.8%. Differences in the yield of starch obtained by the literature due to inaccuracy. In this experiment also performed a starch test using 1% iodine from each ingredient is added 1% iodine so that the cassava yield is initially white to be dark blue, the potato is initially brown to purple, the corn which originally yellow into purple and the sago Initially turbid white to purple. From the results of color changes in accordance with the literature that states that the starch hydrolyzed polysaccharides will form a dark blue to purple. 

F.      Conclusion

From the experiment result can be concluded as follows:

·         Carbohydrates are polyhydroxy aldehyde compounds which combine monosaccharide polymers with the formula of molecules Cn (H2O) n.

·         Amount of cassava yield obtained was cassava 4.32%, potato 8.4%, corn 6.64%, sago 6%.