Question

One mole of nitrogen dioxide has 6.02 x 10²³ nitrogen dioxide molecules. If nitrogen dioxide is made of one nitrogen atom and two oxygen atoms, then one mole of nitrogen dioxide will weigh ________ grams.
Since nitrogen dioxide has a density of 1.5 grams/milliliter, then one mole of nitrogen dioxide will occupy _______ milliliters of space.

(I got 46.01 and 31.) Is this correct? If not, please show your work and round your answer using the correct number of significant digits.

Answer 1

molar Mass = 46.01

Volume = 31

Part One

The 6.02*10^23 is not used here. What you are asked for to begin with is the molar mass of NO2. That comes off the periodic table. Since all periodic tables vary slightly, I could get an answer that is just a bit different from the one you have. I'm going to use whole numbers. It is the calculation that is important, not the sig digs.

1 nitrogen =   1 *  14  = 14 grams/mole

2 oxygens=   2 * 16 = 32 grams/mole

1 Mole = 46 grams / mole

Part Two

Formula

Density = mass / volume

Givens

Density = 1.5 grams / mL

Mass = 46 grams

Volume = ???

Solution

1.5 = 46 / volume                          Multiply both sides by volume

1.5*volume = 46/volume * volume

1.5*volume = 46                            Divide by 1.5

volume = 46/1.5

Volume = 30.7

Since 1.5 only has 2 sig digs, the answer should be 31.

Answer 2

Your answer, IMHO, is correct.

The detailed work is below:

1) to calculate the mass of one mole of nitrogen dioxide (NO₂): 14+2*16=46 (gr/mole);

it means, the mass of 1 mole of NO₂ is 46 gramms. Then

2) to calculate the space in milliliteres: V=mass/density=46/1.5=30.(6) (millilitres)≈31 ml.