# Calculate the force of an explosion from chemical reaction?

1. Oct 30, 2015

### yrjosmiel73

Example, I have a mixture of 5 grams of oxygen and 10 grams of hydrogen. I ignite them. How much force will the explosion do?

Yes, I did think about posting this in the chem category but this is about forces, right?

2. Oct 30, 2015

### Staff: Mentor

Sorry, but that's an extremely complicated, but largely meaningless question. It depends on both the explosion and the distance, shape, strength and mass of the object being impacted, and even then is a pretty weak description.

Now, sometimes maximum over pressure is used, but more common is energy.

3. Oct 30, 2015

### jbriggs444

Note that the molecular weights of hydrogen and oxygen are very different. You would need mass ratio of approximately eight to one in favor of oxygen to achieve a number-of-atoms ratio of two to one in favor of hydrogen.

I assume that you are trying to specify a perfect mix here.

4. Oct 30, 2015

### bigfooted

https://en.wikipedia.org/wiki/Heat_of_combustion#Heat_of_combustion_tables

When you burn hydrogen it will release 120 MJ/kg (The lower heating value means that you do not take into account the condensation of the water vapor in combustion). Pressure and force depend on how this energy is released and are very case-dependent.