A reaction of 0.028g of magnesium with excess hydrochloric acid generated 31.0 mL of a gas. The gas was collected by water displacement in a 22 degree celsius water bath. The barometric pressure in the lab was 746 mm Hg. Using Dalton's Law and the vapor pressure of water at 22 degrees celsius, calculate the partial pressure of hydrogen gas. Use the combined gas law to calculate the "corrected" volume of hydrogen at STP.
2007-10-08 12:20:00 · 1 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
The vapor pressure of water at 22C is 19.827mmHg.
746mmHg total - 19.8mmHg H2O = 726.2mmHg H2
That's the first answer.
Combined gas law: P1V1/T1 = P2V2/T2
V2 = P1V1T2/T1P2
22C = 295K
STP: 273K, 760mmHg
V2 = (726.2)(31.0)(273)/(295)(760) = 27.4mL H2 at STP
That is the second answer.
2007-10-08 12:41:35 · answer #1 · answered by steve_geo1 7 · 0⤊ 0⤋