Description
Specifications Table
Product Name – Potassium hydrogen phthalate LR
Quantity/Pack Size – 500 g
Form – Crystalline powder
Grade – Laboratory Reagent (LR)
Application – Primary standard for titrations, pH buffer preparation, volumetric analysis
Product Overview
Potassium hydrogen phthalate LR is a premium-grade crystalline compound widely recognized as a primary standard in analytical chemistry due to its exceptional purity, stability, and non-hygroscopic nature. This laboratory reagent (LR) grade variant ensures minimal impurities, making it ideal for precise acid-base titrations, pH meter calibration, and volumetric analysis where accuracy is critical. Its high molecular weight (204.22 g/mol) and well-defined composition allow for exact molar solutions, eliminating the need for standardization against secondary references. The compound’s low reactivity with atmospheric moisture ensures long-term stability in storage, while its excellent solubility in water (up to 8 g/100 mL at 25°C) facilitates easy preparation of standard solutions. Unlike technical-grade alternatives, this LR-grade phthalate undergoes rigorous quality control to meet strict laboratory requirements, including compliance with pharmacopeial standards for residual heavy metals and organic impurities. Its neutral pH in solution (when unbuffered) and resistance to oxidation further enhance its reliability in quantitative chemical testing. Whether used in educational labs for teaching titration techniques or in research settings for method validation, this potassium hydrogen phthalate delivers consistent, reproducible results without batch-to-batch variability.
FAQs
1. What is the difference between potassium hydrogen phthalate LR and AR grades?
LR (Laboratory Reagent) grade is suitable for general lab applications and educational use, while AR (Analytical Reagent) grade undergoes additional purification for high-precision analytical work, with stricter limits on impurities like heavy metals and insoluble matter. For most titration and pH calibration needs, LR grade provides sufficient accuracy.
2. Can this compound be used to prepare a 0.1N standard solution for titrations?
Yes, potassium hydrogen phthalate LR is commonly used to prepare 0.1N (0.05M) standard solutions due to its high molecular weight and stability. Dissolve 10.21 g in distilled water and dilute to 500 mL to obtain a 0.1N solution, assuming 100% purity. Always verify the exact molar concentration via standardization if critical accuracy is required.
3. How should potassium hydrogen phthalate be stored to maintain its purity?
Store the compound in a tightly sealed container, preferably in a cool, dry place away from direct sunlight and moisture. While it is non-hygroscopic, prolonged exposure to humid environments can introduce trace water content. Avoid storing near volatile chemicals or strong oxidizing agents to prevent contamination.
4. Is this product compatible with automatic titrators and pH meters?
Absolutely. The high purity and consistent composition of LR-grade potassium hydrogen phthalate make it fully compatible with automatic titrators and pH meters. It is often used as a calibration standard for pH electrodes (especially at pH 4.0) and as a primary standard for acid-base titrations in automated systems.
5. What alternatives exist if potassium hydrogen phthalate is unavailable?
For acid-base titrations, sodium carbonate (anhydrous) or benzoic acid can serve as alternatives, though they require drying before use. For pH buffer preparation, pre-mixed buffer tablets (e.g., pH 4.0 or 7.0) or citric acid-phosphate buffers may be substituted, but these lack the primary standard status of phthalate.
