What is the numerical setup for calculating the number of moles of #CO_2# present in 11 grams of #CO_2#?

1 Answer
Jan 1, 2017

Answer:

Here's how to get the numerical setup.

Explanation:

You must use the molar mass of #"CO"_2# as a conversion factor to convert grams of #"CO"_2# to moles of #"CO"_2#.

The molar mass of #"CO"_2# is 44.01 g/mol.

Thus, the conversion is either (a) #("44.01 g CO"_2)/("1 mol CO"_2)# or (b) #("1 mol CO"_2)/("44.01 g CO"_2)#.

You want an equation like

#"11 g CO"_2 × "conversion factor" = "? mol CO"_2#

The conversion factor must have the desired units of your answer (#"mol CO"_2#) on top, so you choose option (b).

The numerical setup is

#11 color(red)(cancel(color(black)("g CO"_2))) × ("1 mol CO"_2)/(44.01 color(red)(cancel(color(black)("g CO"_2))))= "0.25 mol CO"_2#

Note that the units of "#"g CO"_2#" cancel and give you the correct units for the answer.