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hardie · Jan 6, 2010, 03:28 AM

Hi

Can anyone help me with the word/symbol equation for hydrochloric acid and sodium chloride please?

Thanks

Clough · Jan 6, 2010, 05:07 AM

Hi, hardie!

Please click on the following links.

Hydrochloric Acid Equation Symbol - Google Search

Hydrochloric Acid Equation Symbol - Google Images

Sodium Chloride Equation Symbol - Google Search

Sodium Chloride Equation Symbol - Google Images

You can vary the words in the searches to get even more results.

Thanks!

Unknown008 · Jan 6, 2010, 10:48 AM

Well, the way I learned to write the formulae of simple compounds is by using the valency of each concerned element.

Hydrogen has a valency of 1
Chlorine has a valency of 1

Hence, hydrochloric acid is written as HCl

Sodium has a valency of 1.

Hence, sodium chloride is written as NaCl.

If I had water, containing oxygen and hydrogen only.
Oxygen has a valency of 2.

Hence, the formula for water is $H_2O_1\ and\ becomes\ H_2O$

It is as if you write the symbols, with the valency of the other element.

Another example, aluminium oxide.
Aluminium has a valency of 3, oxygen 2.

Aluminium oxide => $Al_2O_3$

On a further note, it happens when you have two valencies having a common factor other than one.

Magnesium oxide is an example.

Magnesium has a valency of 2, as does oxygen.

Magnesium oxide is written as $Mg_2O_2$ .

But, since they have a common factor, you reduce it to its lowest terms, becoming $Mg_1O_1$ and eventually $MgO$ .

A last example, carbon dioxide, carbon valency 4.
This becomes $C_2O_4$ then finally to $CO_2$ .

I hope it helped! :) I know it's a bit lengthy, but it may help you get to the top in your class in understanding how to write formulae of compounds. :)

Note: Some elements can have multiple valencies, depending on the circumstances. For example, carbon has valencies 2 and 4. Reaction with oxygen can produce either carbon monoxide (CO) or carbon dioxide ( $CO_2$ ).