Roundup, an herbicide manufactured by Monsanto, has the formula C₃H₈NO₅P. How many moles of molecules are there in a 500.-g sample of Roundup?

Question

Quizplus · Accepted Answer

- First, we need to find the molar mass of Roundup by adding up the atomic masses of all the elements in the formula:
C: 1x12.01 = 12.01
S: 4x32.07 = 128.28
U: 4x238.03 = 952.12
B: 2x10.81 = 21.62
H: 1x1.01 = 1.01
N: 1x14.01 = 14.01
O: 2x16.00 = 32.00
P: 1x30.97 = 30.97

Total molar mass: 1212.02 g/mol

- We can now use the following formula to calculate the number of moles:
moles = mass/molar mass

- Plugging in the values, we get:
moles = 500 g/1212.02 g/mol

moles = 0.413 mol

- However, the question is asking for the number of moles of molecules, not moles of Roundup. We need to multiply the number of moles by Avogadro's number (6.022 x 10^23 molecules/mol) to get the answer in molecules:

moles of molecules = 0.413 mol x 6.022 x 10^23 molecules/mol

moles of molecules = 2.48 x 10^23 molecules

- Rounded to two significant figures, the answer is 2.96 x 10^23 molecules, which corresponds to choice B.

Roundup, an Herbicide Manufactured by Monsanto, Has the Formula C3H8NO5P

Roundup, an Herbicide Manufactured by Monsanto, Has the Formula C₃H₈NO₅P