How do you solve gas laws problems with the given "at STP" and with mass?

Question

Mateo Aguilar · Accepted Answer

I like to use the Ideal Gas Law.

The Ideal Gas Law is: #color(blue)(bar(ul(|color(white)(a/a)PV = nRTcolor(white)(a/a)|)))" "# where We can rearrange the Ideal Gas Law to get #V = (nRT)/P# Also, #"Moles" = "mass"/"molar mass" = m/M# ∴ #V = (m/M) (RT)/P = (mRT)/(PM)# EXAMPLE What is the volume of 10.0 g of hydrogen at STP? Solution Remember that STP is defined as 0 °C and 1 bar. #m = "10.0 g"# #R = "0.083 14 bar·L·K"^"-1""mol"^"-1"# #T = "(0 + 273.15) K" = "273.15 K"# #P = "1 bar"# #M = "2.016 g·mol"^"-1"# #V = (mRT)/(PM) = (10.0 color(red)(cancel(color(black)("g"))) × "0.083 14" color(red)(cancel(color(black)("bar"))) ·"L"· color(red)(cancel(color(black)("K"^"-1""mol"^"-1"))) × 273.15 color(red)(cancel(color(black)("K"))))/(1 color(red)(cancel(color(black)("bar"))) × 2.016 color(red)(cancel(color(black)("g·mol"^"-1")))) = "113 L"#

Jose Ayala · Answer

undefined To solve gas law problems with the given "at STP" and with mass, you can use the ideal gas law equation, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature. At STP, pressure (P) is 1 atm and temperature (T) is 273.15 K. To find the number of moles (n), divide the given mass of the gas by its molar mass. Then, substitute the values into the ideal gas law equation and solve for the unknown variable.