Hanna Instruments HI 901 - Manual (Page 130)

A2-4
APPENDIX 2
and back titrate the remaining acid with NaOH to determine the amount of CaCO
3
present.
2HCl excess + 2NaOH —> 2NaCl + 2H
2
O
In order to obtain an accurate value for the concentration of the titrated antacid, we need to
know the exact concentration of NaOH and HCl used.
The final concentration is expressed as mg/g CaCO
3
.
A1.3.2 Setting Up the Method Parameters
Use the following parameters to program the method (see 5.5 Method Options section):
Name: Antacid Power
Titration Type: Back-Titration
Titrant 1 pump: Pump 1
Titrant 2 pump: Pump 2
Break at titrant change: YES
Dosing Type: Dynamic
min Vol: 0.010 mL
max Vol: 0.500 mL
delta E: 4.500 mL
End Point Mode: pH 1EQ points, 1st Der
Recognition Option:
Threshold: 500 mV / mL
Range: NO
Filtered Derivatives: NO
Pre-Titration Volume: 0.000 mL
Pre-Titration Stir Time: 5 Sec
Measurement Mode: Signal Stability
delta E: 0.3 mV
delta t: 1.5 Sec
t min wait: 5 Sec
t max wait: 15 Sec
Electrode Type: pH
Calculations: Sample Calc. by Weight
Titrant 1 Units M (mol/L)
Titrant 2 Units M (mol/L)
Final Result Units g/g
Titrant 1 Name: HCl
Titrant 1 Conc.: 1 M(mol/L)
Titrant 2 Name: NaOH
Titrant 2 Conc.: 1 M(mol/L)
Analyte Size: 0.5 g
Analyte Entry: Manual
Titrant 1 Entry: Calculated
Maximum Titrant 2 Volume: 25.000 mL
Stirring Speed: 1500 RPM
Potential Range: -2000.0 to 2000.0 mV
Flow Rate: 30.0 mL/min
Signal Averaging: 1 Reading
In order to start the analysis, both burettes must be filled with needed reagents, as follows:
• Pump 1 must have attached a burette filled with HCl 1 M (mol/L).
• Pump 2 must have attached a burette filled with NaOH 1 M (mol/L).