Question

Determine how many molecules are in 86L of carbon dioxide at STP?

Answer 1

Answer:How can you tell how much gas is in these containers?

Small gas tanks are often used to supply gases for chemistry reactions.  A gas gauge will give some information about how much is in the tank, but quantitative estimates are needed so the reaction will be able to proceed to completion.  Knowing how to calculate needed parameters for gases is very helpful to avoid running out too early.

Conversions Between Moles and Gas Volume

Molar volume at STP can be used to convert from moles to gas volume and from gas volume to moles.  The equality of 1 mole = 22.4 L is the basis for the conversion factor.

Sample Problem One: Converting Gas Volume to Moles

Many metals react with acids to produce hydrogen gas.  A certain reaction produces 86.5 L of hydrogen gas at STP.  How many moles of hydrogen were produced?

Step 1: List the known quantities and plan the problem.

Known

86.5 L H2

1 mol = 22.4 L

Unknown

moles of H2

Apply a conversion factor to convert from liters to moles.

Step 2: Calculate.

Explanation: