Molar volume , percentage yield & atom economy

Formula for molar volume

V=nxV_m

Approximate molar volume of all gases at room temperature (20^oC)

24 litre mol^-1

Approximate molar volume of all gases at 0^oC

22.4 litre mol^-1

What is molar volume dependant on?

Temperature and pressure

Formula for percentage yield

%yield = (actual yield/theoretical yield) x 100

What is actual yield?

The amount that is obtained.

What is theoretical yield?

The amount that would be obtained assuming full conversion of the limiting reagent.

What is percentage yield?

A measure of how much of a product is obtained compared to the amount expected.

Why don’t most chemical reactions have a yield of 100%?

• The raw materials are not pure.

• Some products are left behind in the apparatus.

• Reaction not finished.

• Some reactions give unexpected products.

• Some reactions involve an equilibrium.

Formula for atom economy

%atom economy = (mass of desired products/total mass of products) x 100

What is atom economy?

A measure of the proportion of the total mass that is successfully converted into the desired products.

Statement for a very low atom economy (e.g. 8%)

This reaction route has a very low atom economy and is an inefficient method of producing hydrogen.