Sodium formate, HCOONa, is the sodium salt of formic acid, HCOOH. It usually appears as a white deliquescent powder. Preparation For commercial use, sodium formate is produced by absorbing carbon monoxide under pressure in solid sodium hydroxide at 130 °C and 6-8 bar pressure:[1] CO + NaOH → HCO2Na Because of the low-cost and large-scale availability of formic acid by carbonylation of methanol and hydrolysis of the resulting methyl formate, sodium formate is usually prepared by neutralizing formic acid with sodium hydroxide. Sodium formate is also unavoidably formed as a by-product in the final step of the pentaerythritol synthesis and in the crossed Cannizzaro reaction of formaldehyde with the aldol reaction product trimethylol acetaldehyde [3-hydroxy-2, 2-bis(hydroxymethyl)propanal].[2] In the laboratory, sodium formate can be prepared by neutralizing formic acid with sodium carbonate. It can also be obtained by reacting chloroform with an alcoholic solution of sodium hydroxide. CHCl3 + 4 NaOH → HCOONa + 3 NaCl + 2 H2O or by reacting sodium hydroxide with chloral hydrate. C2HCl3(OH)2 + NaOH → CHCl3 + HCOONa + H2O The latter method is, in general, preferred to the former because the low aqueous solubility of CHCl3 makes it easier to separate out from the sodium formate solution, by fractional crystallization, than the soluble NaCl would be. Properties Physical properties Some sodium formate dihydrate crystals Sodium formate crystallizes in a monoclinic crystal system with the lattice parameters a = 6, 19 Å, b = 6, 72 Å, c = 6, 49 Å and β = 121, 7°.[3] Chemical properties On heating, sodium formate decomposes to form sodium oxalate and hydrogen.[4] The resulting sodium oxalate can be converted by further heating to sodium carbonate upon release of carbon monoxide:[5][4] 2 HCOONa → Δ ( COO ) 2 Na 2 + H 2 ↑ {\displaystyle {\ce {2HCOONa->[\Delta ]{(COO)2Na2}+H2\!\uparrow }}} ( COO ) 2 Na 2 → > 290 o C Na 2 CO 3 + CO ↑ {\displaystyle {\ce {(COO)2Na2->[{} \atop >\ {\ce {290^{o}C}}]{Na2CO3}+CO\!\uparrow }}} As a salt of a weak acid (formic acid) and a strong base (sodium hydroxide) sodium formate reacts in aqueous solutions basic: HCOO − + H 2 O ↽ − ⇀ HCOOH + OH − {\displaystyle {\ce {HCOO^- + H2O <<=> HCOOH + OH^-}}} A solution of formic acid and sodium formate can thus be used as a buffer solution. Sodium formate is slightly water-hazardous and inhibits some species of bacteria but is degraded by others. Uses Sodium formate is used in several fabric dyeing and printing processes. It is also used as a buffering agent for strong mineral acids to increase their pH, as a food additive (E237), and as a de-icing agent. In structural biology, sodium formate can be used as a cryoprotectant for X-ray diffraction experiments on protein crystals, [6] which are typically conducted at a temperature of 100 K to reduce the effects of radiation damage.