# HandWiki:Help/Chemical

## Chemical equations

One can show chemical symbols and equations as shown in this list of examples. Here are a few examples:

$\ce{ CO2 + C -> 2 CO }$

$\ce{ Hg^2+ ->[I-] HgI2 ->[I-] [Hg^{II}I4]^2- }$

$\ce{ H2O }$

$\ce{ Y^99+ }$

$\ce{ ^{227}_{90}Th+ }$

$\ce{ A <=>> B }$

which were programmed as:

<chem>CO2 + C -> 2 CO</chem>
<chem>Hg^2+ ->[I-] HgI2 ->[I-] [Hg^{II}I4]^2-</chem>
<chem>H2O</chem>
<chem>Y^99+</chem>
<chem>^{227}_{90}Th+</chem>
<chem>A <=>> B</chem>


## Cross references

You can reference a block of chemical symbols using CrossReference method. Here is a sentence that references an equation "1":

This example uses <xr id="eqn:In1"/> that illustrates formulas.

<equation id="eqn:In1" shownumber>

$\ce{ Hg^2+ ->[I-] HgI2 ->[I-] [Hg^{II}I4]^2- }$ </equation>

The WikiCode that was used in this example is:

This example uses <xr id="eqn:In1"/> that illustrates complex blocks of equations.

:<equation id="eqn:In1" shownumber>
<chem>
Hg^2+ ->[I-] HgI2 ->[I-] [Hg^{II}I4]^2-
</chem>
</equation>

Note that <xr id="eqn:In1"/> is "clickable" so you can always navigate to the equation you are referencing to.

## Exporting chemical formulae

HandWiki allows extorting articles to the LaTeX format. In addition, one can export separate equations and chemical formula to MathML and LaTeX. Navigate the mouse to the equation/formulae and use the left button to pop-up the MathJax menu. The select the needed export format. See the example: