Carbonated drinks, carbon dioxide release

Note that the carbon electrode takes part in the reaction. From the reaction stoichiometry, we can calculate that a current of 1 A must flow for 80 h to produce 1 mol A1 (27 g of aluminum, about enough for two soft-drink cans). The very high energy consumption can be greatly reduced by recycling, which requires less than 5% of the electricity needed to extract aluminum from bauxite (Box 14.1). Note also that the production of 1 tonne of aluminum is accompanied by the release of more than 1 tonne of carbon dioxide into the atmosphere. 

The soft drink is initially cooled to 4°C in a fridge. The container is then opened and an aliquot of concentrated sodium hydroxide (40%) is added to quench the carbon dioxide in the product (typically 10 ml of NaOH is added to 284 ml of product). The carbon dioxide is quenched by reaction with the sodium hydroxide to form bicarbonate and carbonate ions. An aliquot (50 /a/) of the quenched product is removed and pipetted into the corning instrument s cell. The cell is closed and the solution acidified to release the carbon dioxide, which is then detected by the change in the thermal conductance of the vapour phase. 

What happens when the pressure of the carbon dioxide gas in a soft drink bottle is released The solubility of the gas in the soft drink solution decreases. 

According to Henry s law, the solubility of a gas in a liquid increases as the pressure increases (c = kP). The soft drink tastes flat at the bottom of the mine because the carbon dioxide pressure is greater and the dissolved gas is not released from the solution. As the miner goes up in the elevator, the atmospheric carbon dioxide pressure decreases and dissolved gas is released from his stomach. 

The next step is to think about what happens when the bottle is opened, a drink is poured out and the bottle reclosed. Opening the botde means the system is no longer closed, so a change to the equilibrium position occurs. Usually, a fizz is heard when the botde is opened. The equilibrium position shifts towards the reverse reaction, releasing carbon dioxide pressure in the head space by diffusion from the drink. 

Water charged with carbon dioxide is termed soda water. It bubbles and fizzes as the gas is released. Soda water is added to syrups in soft drinks and to mixed alcoholic drinks. It does not possess any medicinal properties. 

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