What is the volume of 4.92 grams of hydrogen gas at STP? (Show the work using dimensional analysis)

The volume of 4.92 grams of hydrogen gas at STP is 55 L.

Explanation:

1  mole of an ideal gas will occupy  22.4 L

To find volume, the molar volume of a gas is

22.4 L /  1 mole H 2  →  this takes you from moles of  H 2  to liters

Now, to find the number of moles present in  4.92 g  of hydrogen gas, you can use the gas' molar mass

 4.92  g   1 mole H 2  / 2.016 g  =  2.44 moles H 2

This sample of hydrogen gas will thus occupy

2.44  moles H 2   22.4 L  / 1  mole H 2  =  54.6 L  = 55 L.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.