How many grams are in 1.5x10^25 molecules of CO2? Whats the volume of CO2 @ STP?

Answer 1

Given your other questions, you seem to just totally not have a grasp on dimensional analysis. If you figure that out you could actually do your own homework, so let me explain that to you.

You're basically looking for useful coversions. For example, avogadro's number converts numbers of molecules to moles. STP converts moles to liters. Molecular weight coverts moles to grams.

If you divide 1.5*10^25 molecules by avogadro's number, you'll get the number of moles of CO2. If you multiply that by the molecular weight of CO2 you'll know how many grams there are. Or, if you multiply the number of moles by the STP conversion (24 L / mole), you'll get the number of liters, which is the volume.

I hope this explanation helps you to understand this, because you'll find out very quickly people here don't like to actually do your homework for you.

Answer 2

To do the first part of your question you need the following:

1) Avogadro's number of molecules per mole of CO2. [Avogadro's number of ANYTHING is 6.02 x 10^23].

2) You need the mass in grams of one mole of CO2. (compute this from your periodic table by adding up the mass of one C and two O)

Now, take your original number (1.5 x 10^25 molecules CO2) and multiply it by 1 mole CO2/6.02 x 10^23 molecules of CO2 then multiply by the number of grams CO2/1 mole CO2. Cancel your units and you have your answer.

The second part of your question: STP means "standard temperature and pressure".
Standard Temperature is 0 degrees Celcius or 273 Kelvin (you always use Kelvin degrees in gas law problems). Standard pressure is 1 atm.

Once you get your grams, convert to moles.

Now you can use the ideal gas law.

PV = nRT

P is pressure = 1 atm
V is volume and this is what you are looking for.
n = the number of moles of your CO2
R = the gas constant [0.082 L x 1atm/1mol x K]. T is your temperataure which is 273 K.

Rearrange your formula to isolate V and plug in your values. Cancel like units, multiply and divide and you will have your answer. Your answer will have the units Liters. If it doesn't then you set your problem up incorrectly.

CHEMISTRY TEACHER