using english rendement chemistry

using english Rendement about chemistry

Practical Report on Analytical Chemistry Basics

Method: Gravimetry

Sub Method: Gravimetry Cation

Precipitation of Cation Pb2 + as Deposition of PbCrO4 with K2CrO4 Reagent 

by Gravimetris

1. Destination Experiment:
1.1 Precipitation of the cations of the sample by the Gravimetric method.
1.2 Use of a precipitating reagent in accordance with the Gravimetri method.
1.3 Precipitate Pb2 + cations from sample Pb (CH3COO) 2 as a pure Gravimetric
    PbCrO4
 
2. Basic Theory
Gravimetry is one of the quantitative methods of analysis by means of weighing 
the pure precipitate. The first stage of gravimetric analysis is the separation 
of the components to be known from the other components contained in a sample 
and then carried out the precipitation. The measurement in the gravimetric 
method is by weighing, the number of components analyzed is determined by 
the relationship between the sample weight to be analyzed, the relative 
atomic mass, the relative molecular mass and the weight of the precipitated 
reaction.

In this method there are some important technical steps and need to be considered, 
which include:
1. The process of precipitation of substances (component samples with reagents
2. The filtration process of the precipitate
3. Washing process from sediment
4. Drying process with or without annealing (oven / bunzen)
5. Weighing process of sediment (constant weight)
3. Observation Data 
Not all gravimetric methods are based on precipitation formation, some are based 
on the excision of a component as a gas, then the reaction product is weighed. 
For example, carbonate determination can be done by adding acid, so the carbonate 
decomposes into carbon dioxide gas and then the gas is captured and weighed. 
Gravimetry is the oldest and cheapest way of analysis. It's just that gravimetry 
takes a relatively long time and can only be used for considerable component 
content.

Samples (Pb (CH3COO) 2) with a thorough weight = 0.48 grams,
Contains "Cation" (Pb2 +) with the theoretical weight of the calculation
Equal to = 0,3058 gram-ion.
The reagents used (K2CrO4-0.1M) containing "Anions" (CrO42-),
With the amount of volume used for quantitative or perfect deposition
(Until over saturated) = 8.0 milliliters.
Basic Reaction: Pb2 + + CrO42- ↔ PbCrO4 ↓ yello (Samples) (reagents)
The weight of the settling apparatus (evaporating cup) = 28.56 grams
                                     (Filter paper) = 0.55 grams
          Drying / heating time and weighing period = 8 minutes
Sample Weight:(Pb (CH3COO) 2) 
Volume Reagents:(K2CrO4)Weight Tool and Sludge:
(Drying / Heating-Weighing Weight Pure Deposition:(PbCrO4)0.48 grams

1. Form :Cation = 0,3058 gram-ion Concentration:0.1 M

Volume:8.0 mL 1. 29.45 grams2. 29.43 grams3. 29.42 grams 4. 29.42 gram 0.31 gram 
Pure precipitate weight = 
(cup weight + filter paper + sediment) - (cup weight + filter paper)  
                      = 29,42 - (28,56 + 0,55)                                   
                      = 29.42 - 29.11                                   
                      = 0.31 gram-ion  
Calculation:     Theoretical Weight Cation =
 Weight Cation of the sample (Pb (CH3COO) 2) / Pb2 +                                    
= Ar Pb2 ​​+ / Mr Pb (CH3COO) 2 x sample weight= 207.19 / 325.19 x 0.48 grams
= 0.6371 x 0.48 grams= 0.3058 gram-ion Practical Weight Cation 
= Weight Cation from Deposition (PbCrO4) / Pb2 +                                    
= Ar Pb2 ​​+ / Mr Pb (CH3COO) 2 x by weight of pure precipitate
= 207.19 / 325.19 x 0.31 grams= 0.1975 gram-ionConclusion:Rendemen 
= Practical Results / Theoretical Results x 100%                        
= Weight Cation Deposition / Weight Cation Sample x 100%                        
= 0.1975 gram-ion / 0,3058 gram-ion x 100%                          
= 64.5%
4. Conclusions            
From the experiments that have been done obtained the following conclusions:
1. To precipitate Pb2 + cations from sample Pb (CH3COO) 2 was carried out by 
Gravimetric method.
2. In the precipitation of Pb2 + cations from sample Pb (CH3COO) 2 by Gravimetris
is used K2CrO4 settling reagent ie with the formation of yellow PbCrO4 precipitate.
3. In the Pb2 + cation settling experiment from sample Pb (CH3COO) 2 as PbCrO4
precipitate pure by Gravimetris obtained 64.5% yield.