Visit to the Talta Laboratory: Potentiometric Titration for Determining Silver Content
Recently, I visited the ‘Talta’ laboratory in Tel Aviv, where I closely followed the precise scientific process for determining silver content in metallic alloys using potentiometric titration. This process is divided into several critical stages to ensure reliable and accurate results.
Step 1: Drilling the Sample and Obtaining Chips
For an accurate analysis, a representative sample must be taken from the examined material. If it is a solid metal piece (such as a silver ingot or an alloy component), a controlled mechanical drilling is
performed to obtain fine chips. This ensures that the sample represents the overall chemical composition of the material rather than just the surface, which may differ due to oxidation or contamination.
Step 2: Precise Weighing of the Chips
Once the chips are obtained, they are subjected to precise weighing using analytical balances with an accuracy of at least 0.0001 grams. Accurate weighing is crucial for the final calculation of the silver
content, as even a minor deviation in weight can affect the final result.
Step 3: Dissolution in Acid
The chips are placed in a glass beaker and dissolved in concentrated
nitric acid (HNO₃). This reaction completely dissolves the silver and any accompanying metals, releasing nitrogen dioxide (NO₂) gases. This process is conducted under a chemical fume hood with vapor filtration to ensure maximum safety.
Step 4: Dilution with Water
After dissolution, distilled water is added to the system to reach the appropriate concentration for titration. The dilution allows for better control over the chemical reaction during titration and prevents unwanted side reactions that could interfere with the measurement’s accuracy.
Step 5: Connecting to the Titrator and Performing the Titration
The diluted solution is placed in a titration vessel connected to a
potentiometric titrator. The process proceeds as follows:
A silver/silver chloride (Ag/AgCl) electrode is inserted to measure changes in electrical potential.
A controlled dropwise addition of sodium chloride (NaCl) solution at a 0.1M concentration begins while recording voltage
changes.
The voltage changes are monitored until a sharp drop in potential is observed, indicating the equivalence point at which all silver ions have reacted.
Step 6: Data Collection and Calculation of Silver Content
At the end of the process, the data from the titrator is collected, and the silver content is calculated using the formula:
Silver content in%=(V*C*M)*100/m
Where:
V– Volume of the added NaCl solution .
C– Concentration of sodium chloride solution (0.1M).
M– Molar mass of silver (107.87 g/mol).
m– Sample weight (in grams).
Accuracy of the Method and Its Advantages
The potentiometric titration method is considered highly accurate and reliable for determining silver content, especially when a quantitative assessment of precious metals is required. Some of its key
advantages include:
✅ High precision – The equivalence point is automatically identified using an electrode, independent of visual indicators.
✅ Suitable for complex samples – Works well with various alloys and is not affected by colors or side reactions.
✅ High reproducibility – The results can be replicated with very high accuracy, making it ideal for quality control.
Conclusion
My visit to the Telta laboratory allowed me to witness the precision and meticulousness required for determining silver content using potentiometric titration. This process combines exact science, advanced technology, and professional expertise, providing crucial
information for the precious metals industry, recycling, and silver trading.
Special thanks to Aviva and the Talta Laboratory team for their warm hospitality and the opportunity to learn about their work processes.