Potassium Bicarbonate: Uses, Grades and Safety

Potassium bicarbonate, also called potassium hydrogen carbonate, is a white crystalline powder. It behaves much like baking soda (sodium bicarbonate): it is mildly alkaline and releases carbon dioxide when it meets an acid. The difference is that it brings potassium instead of sodium.

• Formula: KHCO3
• CAS number: 298-14-6
• Molar mass: 100.12 g/mol
• Solubility: about 224 g per litre of water at 20 °C, much more soluble than baking soda
• Heating: breaks down between about 100 and 120 °C into potassium carbonate, water and carbon dioxide

Azlok sells potassium bicarbonate powder in a 400 g pack, listed for food and industrial utility use. Before you use it in food, check the pack label for food grade marking and FSSAI details, and use it within FSSAI limits.

For lab, cleaning, water and workshop work, the same pack serves as a general utility grade. If your work needs a certified purity, such as analytical titrations, ask for a certificate of analysis before buying. See today's price per kg.

Food processing (food grade only)

• Leavening agent in baked goods, often where makers want less sodium than baking soda gives
• Mineral additive in some bottled and soda water
• Reducing excess acidity in wine during winemaking

Lab and education

• Bicarbonate buffers and acid neutralisation
• Demonstrating carbon dioxide release with acids

Industry and other

• Main ingredient in Purple-K type dry chemical fire extinguishers
• Raising the pH of acidic soil and water
• Starting material for other potassium salts

Water and hydroponics

• Raising pH and alkalinity in water for aquariums, home brewing and hydroponic nutrient tanks, while adding potassium rather than sodium

Making a solution. Dissolve the powder in room temperature water, not hot water, because heat drives off carbon dioxide. For a 5% solution, dissolve 50 g in water and make up to 1 litre. Stir until clear.

Neutralising acid. Add the powder or solution slowly to the acid, a little at a time, in an open container. Keep going until fizzing stops, then check with pH paper.

Baking. Use only a pack marked food grade. Potassium bicarbonate can stand in for baking soda in roughly equal weight, since their leavening action is close. It needs an acid in the recipe (curd, lemon juice, buttermilk) to work, and it tastes slightly different.

Raising pH of water. Add small amounts, for example 1 g to 10 litres at a time, stir well, wait 15 to 30 minutes and test again with a pH meter or strips. Going slowly avoids overshooting.

Lab demonstration. Put 2 to 3 g in a flask, add dilute acid slowly and lead the gas through limewater to show carbon dioxide.

• Dust can irritate eyes and the nose. Avoid rubbing your eyes while handling it, and rinse with water if any gets in.
• Wear gloves for long jobs with concentrated solutions.
• Never mix it with acid in a closed bottle. The gas builds pressure and can burst the container.
• Store in a tightly closed container in a cool, dry place. It slowly absorbs moisture and cakes.
• Keep any non-food stock clearly labelled and away from the kitchen.
• Keep away from children.
• Small amounts can be dissolved in plenty of water and poured down the drain.

The 400 g pack is a sensible size for home bakers testing a lower-sodium recipe, small wine batches, lab buffers or garden trials. It also keeps well if stored dry.

For food, confirm the label shows food grade and FSSAI details. For analytical lab work, ask for a certificate of analysis. If you only need it now and then, buy a single pack rather than storing a big bag that may cake in humid weather. Bakeries, labs and factories that need 25 kg or more can send a bulk inquiry.