100g Caustic Soda Powder at Cheap Price

100g Caustic Soda Powder at Cheap Price is a small-quantity packaged solid sodium hydroxide (NaOH), CAS 1310-73-2, EC 215-185-5, molar mass 39.997 g/mol. The product model is designated CP-100 NaOH Powder; net content is 100 g of solid technical-grade sodium hydroxide, excluding packaging and desiccant. The “cheap price” designation describes a low total acquisition cost for a 100 g technical-grade unit, not a relaxation of hazard classification or specification limits. The material is a white, deliquescent powder supplied in a heat-sealed aluminum-foil laminate pouch or an induction-sealed high-density polyethylene bottle, depending on regional distribution. Transport classification is UN 1823, Class 8, Packing Group II for solid sodium hydroxide. The powder is intended for small-batch pH adjustment, cleaning formulation, saponification, and general alkaline process work where bulk flake or drummed liquid would exceed immediate inventory requirements or where a dry, pre-weighed dose is preferable.

Why Does the Powder Morphology Alter Dissolution Rate, Dusting, and Storage Stability?

Powdered sodium hydroxide differs from flake, prill, and pellet forms primarily by particle-size distribution and exposed surface area. A technical-grade powder typically reports ≥90% passing a 0.5 mm sieve according to ISO 565, and milled or ground product can have a median particle size between 150 µm and 300 µm by laser diffraction. Flake and prill products are retained on larger mesh fractions. The higher specific surface area accelerates the initial hydration step when the solid is added to water at 15–25 °C, but it also increases atmospheric moisture uptake and carbon dioxide reaction. In a mechanically agitated reactor with a 300 rpm polypropylene impeller and water at 20 °C, a 10% w/v powder dispersion typically clears faster than flake of equivalent mass; however, published data for this specific configuration is limited, and the difference is more pronounced in low-shear mixing than in high-shear homogenization. Dissolution is not solely surface-area controlled. The standard enthalpy of solution of sodium hydroxide is approximately −44.5 kJ/mol; in poorly agitated water, powder can generate a hot, dense alkaline layer at the vessel bottom, creating thermal stratification that delays complete mixing. Therefore, the powder should be added through the vortex of a mechanically stirred body of water, and the vessel should be made of high-density polyethylene or polypropylene, not aluminum or unlined steel. Dust generation is the primary operational penalty. Particles below 100 µm can become airborne during manual transfer, producing an alkaline aerosol subject to a NIOSH REL ceiling of 2 mg/m³ and an ACGIH TLV ceiling of 2 mg/m³ as NaOH. Flake and prill forms release less dust but dissolve more slowly and are easier to handle in open-top tanks.

Batch-to-batch variance in technical-grade sodium hydroxide powder is most commonly observed in residual sodium carbonate and in the fraction of fine particles passing a 0.15 mm sieve. This variability is introduced during crystallization, milling, and packaging under ambient humidity. Production-scale manual addition stations should therefore use local exhaust ventilation with a capture velocity of at least 0.5 m/s at the pour point and should avoid aluminum fixtures near open transfer, because alkaline dust can corrode unprotected aluminum and zinc surfaces. A 100 g pouch is intentionally small enough to be poured in a single dose into a 5–20 L high-density polyethylene or polypropylene mixing vessel, which reduces open-container exposure time and limits dust accumulation.

Material Specification and Certificate-of-Analysis Limits

The technical-grade powder is specified to a minimum NaOH mass fraction consistent with GB/T 209-2018 Grade IS-IT I or equivalent industrial grade. The CP-100 NaOH Powder model is not sold as a pharmacopeial or analytical reagent; trace-metal and insoluble-matter limits are therefore broader than those for reagent-grade pelletized sodium hydroxide. The lower unit price arises partly from this specification difference, not from absence of quality control. Compliance with ASTM E291-18 should be verified for the specific lot. Manufacturers typically use acid-base titration with 1 mol/L hydrochloric acid to a phenolphthalein endpoint for assay determination; carbonate is estimated by a second-titration or gas-evolution method. Because sodium hydroxide powder absorbs carbon dioxide from air, the sodium carbonate specification should be re-checked after repeated opening. A package opened at RH >60% without desiccant may drift above the original carbonate limit and form surface crusts that reduce free-flowing behavior. The 100 g net weight is not a use quantity; it is selected for one-time or short-term trial use, and it reduces the need for operators to split larger bulk containers under uncontrolled humidity.

For quantitative preparation of a stock solution, the operator should add powder to water, never water to powder. A 20% w/v stock solution is prepared by slowly adding 200 g of powder to 800 mL of stirred deionized water at 15–25 °C in an HDPE or PP vessel, then making up to 1000 mL after cooling. The dissolution is exothermic: the standard enthalpy of solution of sodium hydroxide in water is approximately −44.5 kJ/mol. Under adiabatic conditions, a 5% w/v solution can rise by approximately 13 °C and a 10% w/v solution by approximately 26 °C relative to the initial water temperature; a 20% w/v preparation can exceed 50 °C and therefore requires slow addition and possible external cooling. The solution should be allowed to reach ambient temperature before final volume adjustment because thermal expansion affects volume calibration. Prolonged storage of dilute sodium hydroxide in glass is not recommended because the alkaline solution slowly attacks borosilicate glass and leaches silicate.

When the Powder Is Pre-Diluted for pH Adjustment in Water Treatment and Cleaning

For industrial water pH correction, the 100 g powder is usually pre-diluted to a 10–20% w/v stock solution before metering into low-alkalinity process water. The dose depends on raw-water alkalinity, dissolved carbon dioxide, contact time, and target pH. pH should be measured with a calibrated meter according to ASTM D1293-18. In carbonate-free water, raising pH from 7.0 to 12.0 requires approximately 0.01 mol/L hydroxide, equivalent to 0.4 g/L NaOH; real buffered water can require substantially higher doses because alkalinity consumes added hydroxide. For cleaning-in-place applications, sodium hydroxide solutions are commonly prepared at 10–30 g/L ( 1–3% w/v ) and circulated at 60–80 °C for organic soil removal. A 100 g pouch yields 3.3 L of 3% w/v solution or 10 L of 1% w/v solution. Contact time and temperature must be validated against the specific soil matrix; no universal cleaning efficacy is stated. In food-processing equipment cleaning, sodium hydroxide is permitted under FDA 21 CFR 184.1763 when residues are removed by potable water rinses and the final surface is neutral. For drinking water treatment chemicals within the EU, the product should meet EN 896:2012; users should verify potable-grade compliance before use.

In small-scale stainless steel surface preparation, a 5% w/v sodium hydroxide solution at 60–70 °C can be used as an alkaline degreasing step before passivation. The workpiece is circulated or immersed for 10–20 min, then rinsed with deionized water having conductivity below 5 µS/cm until the rinse pH is neutral. This alkaline cleaning step does not replace passivation or descaling, and it must be followed by an appropriate passivation treatment such as ASTM A967/A967M-17. The 100 g powder is sufficient for 2 L of 5% w/v solution, making it suitable for coupon-level trials rather than production-scale immersion lines.

Stoichiometric saponification and ester hydrolysis are further small-batch uses. The theoretical NaOH demand is calculated from the saponification value: NaOH (g) = oil mass (g) × saponification value (mg KOH/g oil) × 40.0 / 56.1 / 1000. For 500 g of oil with a saponification value of 195 mg KOH/g, the theoretical NaOH demand is approximately 69.5 g. The powder should be dissolved in 1.2–1.5 times its mass of water before addition to the oil phase at 40–50 °C; this prevents localized overheating and avoids adding dry powder directly to hot oil, which can cause splatter and localized hydrolysis. The high surface area of the powder supports faster liquid-phase incorporation than flake, but the operator must control dust and avoid breathing alkaline dust. The stoichiometric calculation is based on saponification value methodology described in AOCS Cd 3-25. Published data for this specific powder configuration is limited, so benchtop validation with a 1 L reactor is recommended before scaling.

Assessing Equivalent Alkalinity Against 50% Liquid Sodium Hydroxide and Potassium Hydroxide

Substitution between dry and liquid alkali sources is calculated on a dry-equivalent hydroxide basis. The 100 g powder contains 2.50 mol of NaOH. A 50% w/w liquid sodium hydroxide solution has a density of approximately 1.53 g/cm³ at 20 °C and a NaOH mass fraction of 50%, giving about 765 g/L NaOH, or 19.1 mol/L hydroxide. Therefore, 100 g of powder is equivalent to approximately 200 g or 131 mL of 50% w/w liquid NaOH on a dry-mass basis. Liquid caustic soda offers pump-assisted metering and lower dust, but the 50% solution has a freezing point near 12 °C; unheated storage in cold environments can cause crystallization and pump cavitation. The solid 100 g powder avoids that phase-transition risk. Compared with potassium hydroxide, KOH molar mass 56.105 g/mol, 100 g of NaOH provides 2.50 mol hydroxide while 100 g of KOH provides 1.78 mol. Sodium hydroxide yields harder saponified products and is generally less costly per mole of hydroxide, but KOH is preferred where higher solubility or softer soap pastes are needed. Compared with sodium carbonate, NaOH gives a more rapid pH rise and does not contribute carbonate alkalinity; however, NaOH is more corrosive to skin and eyes and is regulated under OSHA 29 CFR 1910.1200 hazard communication requirements.

Storage and compatibility boundaries should be defined before purchase. In unopened barrier packaging, the product is typically stable for 12–24 months when stored at 15–25 °C and protected from humidity. Once opened, the powder should be resealed with a desiccant or stored in an airtight container; prolonged exposure at RH >60% produces surface caking and sodium carbonate formation. The material is incompatible with strong acids, ammonium salts, aluminum, zinc, tin, magnesium, and water-reactive metals; closed containers should not be used for dissolving caustic soda in contact with aluminum because hydrogen gas may accumulate. Do not mix the powder with acidic cleaners or acid-based descaling agents. For spill control, use dry inert absorbent and avoid water spray that can create an alkaline mist; the exposure limit for sodium hydroxide is 2 mg/m³ as a ceiling value under NIOSH guidance. This 100 g pack is not intended for continuous process feed or for applications requiring food-grade or analytical-reagent documentation; users should request a lot-specific certificate of analysis to confirm grade suitability.

Spent alkaline solutions from small-batch use should be neutralized with dilute acid under controlled conditions, not discharged directly to drains without pH adjustment. Neutralization should be carried out in an open, ventilated vessel with continuous stirring; the solution pH is adjusted to a range allowed by local discharge permits, commonly 6.0–9.0 in municipal systems, but the exact limit is jurisdiction-dependent. The empty packaging should be triple-rinsed, and the rinse water should be added to the neutralization batch. The packaging may be disposed according to local hazardous waste regulations; because the 100 g size distributes hazardous material in a small quantity, it can simplify waste classification compared with surplus retention of partially used 25 kg bags that have been opened and exposed to humid air.