Name: Jim Zomerveld

Date: 26/09/18

Goal:  We are going to measure the amount of calcium that there  is in different kinds of water sources with the VAAS method.

 

 

Requirements:

-        Monsters

-        Tap water.

-        Lake water

-        Chemicals

-        CaCO₃ P.A.

-        concentrated HCL 

 

Protocols:

The protocols are on page 34 till page 36 of the protocols of period 5.

 

Results: 

Concentation of the stock solution:

weighed: 642 mg

Molar mass: CaCO₃: 100,1 g/mol

Molar mass Ca²⁺: 40,1 g/mol 

 

      100,1 g/mol    40,1 g/mol           =      642 mg x 40,1 g/mol        =   257,44 mg/L 

       642 mg                                                          100,1 g/mol

 

 

Concentration Ca²⁺  of every  solution:

 | Flask  | Ammount stock ( in ml)  | Concentration  Ca²⁺  ( mg/L ) 
 | 1 | 0,2 | 5,15
 | 2 | 0,4 | 10,28
 | 3 | 0,6 | 15,42
 | 4 | 0,8 | 20,56
 | 5 | 1,0 | 25,70

 

 Exsample calculations concentrations:

flask 1:  257,44 mg/l / 100 ml flask = 2,5744 mg/L

2,5744 x 0,2 ml out of the stock pipetted = 0,515 mg/ L 

0,515 / 0,1 L = 5, 15 mg/L

 

 

 

Absorbtion:                                                    

 | Std 1 | 0,2066
 | Std 2 | 0,3706
 | Std 3 | 0,5535
 | Std 4 | 0,6706
 | Std 5 | 0,8052

 

 

     

  Absorbtion monsters: 

 | Lake water 3x diluted |  0,6581
 | Tab water 2x diluted |  0,5764

Absorbtion controle monster:

 | 8,0 mg/l | 0,2743 

                                                                

 

Graphics 1: absorptions flask

 

Y=0,0311x + 0,0342

0,6581 = 0,0311x + 0,0342 à 0,6239 = 0,0311x  

0,6239 = 0,0311x à X= 20,06 x 3 = 60,18 mg/l lake water. 

 

0,5764 = 0,0311x + 0,0342 à 0,5422 = 0,0311x

0,5422 = 0,0311x à X= 17,43 

17,43 x 2 = 34,86 mg/l tab water.

 

Conclusion: 

Of this practical lesson has been concluted that the concentrations of the unknown water monsters is: 

-        lake water: 60,18 mg/l (not diluted)

-        tab water: 34,86 mg/l (not diluted )