Reaction Balancing and Molecular Weight Calculation Tool

A really quite useful webMathematica application by Theodore Gray
Images taken from my Periodic Table Table

Enter a chemical reaction in the field below and the system will automatically balance the reaction for you, calculating the appropriate coefficient to put in front of each compound to balance the total number of atoms of each element on both sides. Enter the formula using the standard element abbreviations (case matters!) and use -> for the reaction arrow, as in the default example.
You can also just enter a single compound to get its molecular weight and composition.
Don't include any coefficients in front of the reactants: The system will add them automatically for you.




Balanced reaction:
2 O2 + CH4 -> 2 H2O + CO2

Balanced weight of reagents:
2 O2
 +
CH4
 ->
2 H2O
 +
CO2
Enter an amount in any field above then click the Set button below that field. The other quantities will be filled in with the weight of the other reagents needed to match the given amount. Or fill in all the starting weights (including zeros on the right if you're starting with only reactants) and click to compute which reagent on the left side will be consumed first, if the reaction proceeds fully. The weights after complete reaction will be shown below the input weights.

Molecular weight and weight-percent composition of each reagent (click on any compound for extensive further information from NIST's website, or on any element to go to my entry for it):
2 O2
31.9988g/M
O 100.%
 +
CH4
16.0425g/M
C 74.8682%
H 25.1318%
 ->
2 H2O
18.0153g/M
H 11.1898%
O 88.8102%
 +
CO2
44.0095g/M
C 27.2912%
O 72.7088%

Balanced reaction in plain text form (useful for copy/paste):
2 O2 + CH4 -> 2 H2O + CO2