Dear Ashokhumar,

Free carbon dioxide is carbon dioxide that exists in the environment. It is present in water in the form of a dissolved gas. Surface water normally contains less than 10 ppm of free carbon dioxide, while some ground waters may exceed that concentration. CO2 dissolves in water, and some of it reacts with water molecules to produce a slightly acid solution called carbonic acid. The (aq) indicates water solution. The hydrogen carbonate compound cannot be isolated as a pure substance - it decomposes easily to produce water and CO2 gas. Carbon dioxide readily dissolves into water to form carbonic acid H2CO3.

CO2(aq) + H2O ←→ H2CO3(aq)

As the amount of carbon dioxide in the atmosphere rises, the oceans absorb a lot of it. In the ocean, carbon dioxide reacts with seawater to form carbonic acid. This causes the acidity of seawater to increase.

The gas is added at high pressure through the drink, until the liquid is saturated with the gas. When the pressure is released the acid will again decompose to carbon dioxide gas.

Regards

Bachir ACHOUR

I support Dr B. ACHOUR. In addition I like to mention that free CO2 in water is originated either from atmosphere through diffusion and may be originated from respiratory products in the aquatic system. It reacts with water to form HCO3 and remains in equilibrium condition with a fixed quantity in available form. By any way if this CO2 is used up by algal community, then it is recovered from dissociation of HCO3 and form CO3. This CO3-HCO3 develops a buffering capacity of the water so that pH of water may not vary to a large extent. Thus, free CO2 initially lower pH but buffering activity revives it and does not allow to change this value to a large extent.Besides, it also develops Phenolpthalien (P) alkalinity and Methyl orange alkalinity(M) in water.

Base on this discussion, it true that all soft drink became acidic, so it is harmful to human health.

The high percentage of free carbon dioxide in water changes the pH and therefore changes many water properties.

Yes pH became acidic

So a CO2 solution of CO2 and water will be slightly acidic which is why sparkling water has a salty/sour taste.

There is a misconception that the carbon dioxide gas, dissolved in carbonated water as carbonic acid, is highly acidic and can damage teeth. However, a 1999 study and a one from 2012 suggest this isn't actually the case, and that the concentration of carbon dioxide doesn't harm the enamel of the teeth.

Carbonated beverage consumption has been linked with diabetes, hypertension, and kidney stones, all risk factors for chronic kidney disease. Cola beverages, in particular, contain phosphoric acid and have been associated with urinary changes that promote kidney stones.

Several studies have shown that, sparkling water hydrates you just as well as still water (and nutritionists tend to agree). This makes sense, considering that carbonated water is just regular water infused with bubbly carbon gas.

Regards

I get good information Bchir Achour sir

When CO2 pass over water some of it dissolve forming carbonic acid, which makes water acidic.

Yes, it is true

The pH of water can indirectly affect your health. Water with acidic pH levels can corrode plumbing and leach metal. Iron, manganese, copper, lead and zinc are commonly found in acidic water. It places adults at risk for health problems such as cancer, stroke, kidney disease, memory problems and high blood pressure.

True! I agree with you Dr. Amal.