CHEM 120 Lecture Notes - Lecture 3: Molar Mass, Root Mean Square, Stoichiometry

• School: McGill University
• Department: Chemistry
• Course: CHEM 120
• Professor: Laura Pavelka

Document Summary

Chem 120 lecture 3 partial pressure & the kinetic theory of gases. In 1965, the us navy detonated 500 tons (500e^3 kg) of tnt on kaho"s island. 2 c7h5n3o6(s) 3n2(g) + 5h2o(g) + 7co(g) + 7c(s) + heat: look at stoichiometry: 2 mols tnt 3+5+7 mols of gas. 7. 5mols gas/mol of tnt decomposed: how many mols of tnt reacted? ntnt = m/m = 500e^3kg *(1000g/kg)/(227g/mol) = 2. 20e^6 mol, how many moles of gas produced? (see last example of 2nd lecture) ngas = ntnt *7. 5. Gay-lussac"s law of combining volumes: gases react in volumes proportional to ratios of small whole numbers. Avogadro: the volumes of gases involved in reactions are proportional to the question stoichiometry. Due to pv=nrt, the identity of the chemical species (ie. ntot) is not really important ntot = na + nb + . Mole fraction of a (fraction of moles that are a) = xa = na/ntot. Mole fraction of b: = xb = nb/ntot.