A(n) 816 ml sample of hydrogen was collected over water at 21.0◦c on a day when the barometric pressure was 755 torr. what volume would the dry hydrogen occupy under standard conditions? the vapor pressure of water at 21.0◦c is 19.0 torr. answer in units of ml.

Asample contains 16.75 g of the radioisotope u-236 and 50.25 g of its daughter isotope, th-232. how long did it take for decay to take place if one half-life of u-236 is 23 million years? 46 million years 69 million years 92 million years 115 million years

Agas mixture with a total pressure of 745 mmhg contains each of the following gases at the indicated partial pressures: co2, 245 mmhg ; ar, 119 mmhg ; and o2, 163 mmhg . the mixture also contains helium gas. part a what is the partial pressure of the helium gas? phe p h e = nothing mmhg request answer part b what mass of helium gas is present in a 10.2-l sample of this mixture at 283 k ? m m = nothing g request answer

Use examples from the article to explain one positive and one negative effect that chemistry has had on society.