Baking soda, also known as sodium bicarbonate, is a common household product used for baking and cleaning. When baking soda is mixed with water or an acid, it produces carbon dioxide gas bubbles that cause batters to rise. This leavening ability makes baking soda a popular leavening agent in baked goods.
In addition to being a leavening agent, baking soda can also increase pH and make substances more alkaline. This is because baking soda is a base. Bases are substances that can neutralize acids and release hydroxide ions (OH-) in water, which increases pH. So when baking soda is dissolved in water, it increases the pH and makes the solution more alkaline.
The Chemistry of Baking Soda
Chemically, baking soda is a salt made up of the sodium cation (Na+) and bicarbonate anion (HCO3-). When baking soda dissolves in water, it dissociates into sodium (Na+) cations and bicarbonate (HCO3-) anions:
NaHCO3(s) → Na+(aq) + HCO3-(aq)
The bicarbonate anions then act as a weak base by combining with and neutralizing hydrogen ions (H+) in the solution:
HCO3-(aq) + H+(aq) → CO2(g) + H2O(l)
This neutralization reaction releases carbon dioxide gas, which provides the rising bubbles in baking applications. More importantly for pH, it removes hydrogen ions, increasing the hydroxide ion (OH-) concentration and making the solution more alkaline.
How Baking Soda Raises pH
When baking soda is added to water, the bicarbonate anions react with and neutralize hydrogen ions, removing them from solution. With fewer free hydrogen ions, the hydroxide ion concentration increases, and this raises the pH.
The pH scale ranges from 0-14, with pH 7 being neutral. Solutions with pH below 7 are acidic, while solutions with pH above 7 are basic/alkaline. Pure water has a neutral pH of 7. When baking soda is added to pure water, the pH increases from 7 to around 8-9, depending on the amount added. This increase makes the solution alkaline.
The impact of baking soda on pH depends on the initial pH of the solution. In acidic solutions with a low pH, baking soda has a more dramatic effect, significantly raising the pH. In alkaline or neutral solutions, the impact on pH is more subtle. But in all cases, baking soda increases pH to some degree by neutralizing hydrogen ions.
Baking Soda pH in Cooking and Baking
In cooking and baking, baking soda is added to doughs and batters to increase pH and help baked goods rise. Some examples:
– Pancakes: Baking soda is added to pancake batter, which starts out mildly acidic from ingredients like buttermilk. The baking soda raises the pH, making the batter more alkaline. This facilitates rising from the carbon dioxide produced.
– Cookies: Many cookie recipes call for baking soda. The baking soda reacts with acidic ingredients like brown sugar, molasses, or lemon juice to increase pH and cause more rising action.
– Bread: Bread dough contains yeast to make it rise. Adding a small amount of baking soda can optimize the pH for yeast activity and improve rising.
So while the main role of baking soda is to produce CO2 for leavening, its alkaline properties also help raise the pH of batters and doughs for better results.
Using Baking Soda to Neutralize Acids
In addition to baking, baking soda can be used to neutralize acids and raise pH in other applications:
– Heartburn relief: Baking soda can provide temporary relief from heartburn by neutralizing stomach acid and raising the pH. It works faster than other antacids.
– Odor removal: Baking soda can help remove odors from fabrics, carpets, and refrigerators by neutralizing acidic odor molecules. This neutralization inhibits the scent.
– Drain cleaner: Pouring baking soda down a drain followed by vinegar creates a fizzing chemical reaction. This can break down buildup of grease and hair in drain pipes by neutralizing their acidic properties.
– Swimming pools: Baking soda is added to swimming pools to raise the pH of the water, keeping it in the ideal range of 7.2-7.8 and preventing damage from low pH.
So baking soda is a versatile base that can rapidly raise pH and neutralize acids throughout the home.
The Effect of Baking Soda on pH of Skin and Hair
Some people use baking soda as part of their hygiene and grooming routine for skin and hair. Because it has an alkaline pH of around 8, baking soda can temporarily raise the pH when applied topically.
Normal skin has an acidic pH between 4-6, while healthy hair has a pH of 4-5. These low pH levels help maintain the skin and scalp’s protective acid mantles against microbes. When baking soda is applied, it raises the pH more into the alkaline range.
This pH change can sometimes provide benefits:
– Dandruff reduction – For some people, the alkaline pH shift can help deter the fungal growth that causes dandruff.
– Gentle cleansing – Baking soda can remove oils and clean hair and skin while being less harsh than alkaline soaps.
However, changing pH long-term by overusing baking soda can disrupt the natural acidity of skin and hair. This can lead to dryness, irritation, and damage. Brief, occasional use of baking soda is likely fine, but regular heavy use should be avoided. Moderation is key for maintaining healthy pH balance on the skin and scalp.
The Optimal pH for Plants
For plants, an optimal soil pH range is between 6-7, mildly acidic to neutral. Most plants grow best in this slightly acidic range. If soil becomes too alkaline with a pH over 7.5, nutrients can become less available to plant roots.
Adding baking soda can raise soil pH, making it more alkaline. This can sometimes be beneficial if the starting pH is very low. However, it’s important not to overdo it with baking soda and push soil pH to unhealthy alkaline levels for extended periods.
A better approach is to add organic compost and mulch. This buffers pH changes in soil and provides nutrients, while releasing acids over time to maintain an optimal mildly acidic pH.
Rapid pH swings can stress plants, so baking soda should only be used occasionally and in moderation to raise garden soil pH if needed. Overuse of baking soda can make soil too alkaline for healthy plants long-term.
Does Baking Soda Change Pool pH?
Baking soda is an important chemical for adjusting the pH in swimming pools. Pool water must be maintained at a pH of 7.2-7.8 to prevent damage to the pool and harm to swimmers’ eyes and skin.
Over time, the pH of pool water drops and becomes more acidic due to the addition of chemicals like chlorine. Baking soda is added to the pool to bring the pH back up into the desired alkaline range.
When baking soda is dissolved in pool water, it releases bicarbonate ions which neutralize hydrogen ions and raise pH. The impact and amount needed depends on the volume of water, the pH drop, and other factors. But in general, baking soda reliably increases pH in pools.
Pool pH should be checked frequently using test strips. Baking soda can then be added periodically to the pool or automatic feeders in measured doses to hold pH steady in the ideal range.
The pH of Baking Soda in Water vs. Vinegar
Baking soda and vinegar have opposite effects on pH when dissolved in water:
– Baking soda solution – Baking soda forms a basic solution with a pH of around 8-9. The alkaline bicarbonate ions raise pH.
– Vinegar solution – Vinegar contains acetic acid, which forms an acidic solution with a pH of around 2-3. The hydrogen ions lower pH.
This difference is why combining baking soda and vinegar creates an acid-base reaction. The two opposite pH effects neutralize each other somewhat, producing carbon dioxide gas and a fairly neutral pH around 7.
Vinegar’s acidic pH makes it great for cleaning and removing stains. Baking soda’s alkaline pH makes it good for neutralizing acids and freshening. Their pH differences are what create that “fizzing” reaction.
Does Baking Soda or Baking Powder Raise pH More?
Baking powder contains baking soda as the key leavening ingredient. However, it also includes an acidic component like cream of tartar.
So which raises pH more?
Baking soda alone has a higher pH around 8-9. When dissolved in water, it will raise the pH more than baking powder.
Baking powder starts with a neutral pH. But when it gets wet, the baking soda component raises pH while the acid lowers it. The overall effect is slightly alkaline, but less so than plain baking soda.
For cooking, the acid in baking powder helps give a rise-pause-rise effect and sustained leavening. For pH, baking soda has a stronger alkaline boost.
Does pH Affect Baking Soda Reactions?
Yes, the pH of the solution affects how fast and strong the reaction of baking soda is.
Baking soda reacts with acids to produce carbon dioxide. Acidic solutions with lower pH provide more available hydrogen ions for baking soda to neutralize, resulting in faster and stronger CO2 production.
Conversely, in neutral or alkaline solutions with higher pH, there are fewer hydrogen ions available, so the reaction is slower and weaker.
For example, baking soda dissolves instantly and reacts vigorously when added to vinegar with a pH of 2-3. But in plain water with a pH of 7, the reaction is much more subtle.
So the lower the pH, the faster and stronger the fizzing reaction baking soda will produce. Food recipes take advantage of this by combining baking soda with mild acids like buttermilk to create the right rising action. Understanding this role of pH helps culinary baking applications.
Conclusion
In summary, baking soda is a versatile base that increases pH and makes solutions more alkaline. When dissolved in water, baking soda releases bicarbonate ions that neutralize acids and raise pH. This property allows baking soda to act as an effective leavening agent in cooking and baking.
It can also neutralize acids and raise pH in many cleaning and home applications, from neutralizing odors to adjusting swimming pool water. Baking soda has a higher pH than baking powder, and works best at lowering pH where more acidic hydrogen ions are available. Understanding the relationship between baking soda and pH helps explain its wide use.
