chemistry

Sodium formate

Sodium formate is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sodium formate rather than just read about it. In short: Sodium formate, HCOONa, is the sodium salt of formic acid, HCOOH. It usually appears as a white deliquescent powder.

Key takeaways

Sodium formate belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sodium formate to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sodium formate from memory before moving on to harder problems.

Reference excerpt

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:

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]. 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

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°.

Chemical properties On heating, sodium formate decomposes to form sodium oxalate and hydrogen. The resulting sodium oxalate can be converted by further heating to sodium carbonate upon release of carbon monoxide:

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 water to form a basic solution:

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, which are typically conducted at a temperature of 100 K to reduce the effects of radiation damage. Sodium formate plays a role in the synthesis of formic acid, it is converted by sulfuric acid via the following reaction equation:

2 H C O O N a + H 2 S O 4 ⟶ 2 H C O O H + N a 2 S O 4 {\displaystyle \mathrm {2\ HCOONa+H_{2}SO_{4}\longrightarrow 2\ HCOOH+Na_{2}SO_{4}} }

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Sodium formate

Start with the simplest possible case. Write down what Sodium formate claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sodium formate before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sodium formate ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sodium formate

In research: Sodium formate appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sodium formate in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sodium formate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Deliquescent materials, Formates, Organic compounds with 1 carbon atom, so understanding it makes those chapters shorter.
In everyday life: Look for Sodium formate outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Sodium formate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sodium formate means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sodium formate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sodium formate in simple terms?

Sodium formate, HCOONa, is the sodium salt of formic acid, HCOOH. It usually appears as a white deliquescent powder.

Why does Sodium formate matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sodium formate?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sodium formate.