How old is the idea that matter is composed of atoms?

What substance has a mass of 9.5g and volume of 2.1cm^3

Using the thermodynamic information in the aleks data tab, calculate the standard reaction free energy of the following chemical reaction: →+p4o10s6h2ol4h3po4s round your answer to zero decimal places.

Hydrogenation reactions, in which h2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. in the simplest case, ethene (c2h4) and h2 form ethane (c2h6). if 140 kj is given off per mole of c2h4 reacting, how much heat (in mj) is released when 12 kg of c2h6 forms?