From: NFetter@aol.com
Date: Sat May 22 2004 - 15:44:55 PDT
From: NFetter@aol.com Message-ID: <14.2a346b9f.2de131e7@aol.com> Date: Sat, 22 May 2004 18:44:55 EDT Subject: Re: pinhole baking soda and water
Hi Jennie,
Sorry to take so long to reply. Baking soda is sodium bicarbonate (NaHCO3).
When tis salt is dissolved in distilled water there is no chemical reaction.
The sodium and bicarbonate ions that are formed when the salt dissolves do not
react with water other than the solvation process which might be called a
chemical reaction. CO2 is released only if the water is acidic (pH less than 7).
When any salt is dissolved in water, two forces are involved. One is the
energy required to pull the ions apart (lattice energy) and this energy is always
endothermic. The other force is the solvation of the gaseous ions with water
molecules and this process is always exothemic. Whether a salt dissolving in
water makes the solution hot or cold depends on which of these energies is
greater.
When ammonia salts in cold packs dissolve in water, the lattice energy is
greater than the solvation energy and the solution gets colder. When sodium
hydroxide (NaOH) dissolves in water the solvation energy is much larger then the l
attice energy and the resulting solution gets very hot. In table salt (NaCl)
the two energies are about equal no thermal effect is obseved when salt is
dissolved in water.
Neil Fetter
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