Question

Find the number atoms found in 320g of urea.​

Answer 1

Answer:

Mass → Moles and Moles → Atoms.

196.967 u . ...

So, if you are given the mass of an element, you use the periodic table to find its molar mass, and multiply the given mass by the reciprocal of the molar mass. ...

Once you have moles, multiply by Avogadro's number to calculate the number of atoms.

Answer 2

Urea, (NH2)2CO, is used for fertilizer and many other things. Calculate the number of N, C, O, and H atoms in 1.68×104 g of urea.

First, I found the total atomic weights of each element in this compound to find the percent composition:

N: 28.02 amu

H: 4.032 amu

C: 12.01 amu

O: 16 amu

Total atomic weight of urea: 60.062

Then, I found the percent composition of urea:

N: 46.65%

H: 6.71%

C: 20.00%

O: 26.64%

Then, I converted 1.68×104 g into moles by dividing this amount in grams by 60.062, and found that it is approximately 279.71 moles.

After that, I took percentages of this to calculate the number of moles of each element in the sample of urea (for example, 46.65% of 279.71 to find the number of moles of nitrogen).

Finally, I multiplied each of these numbers in moles by Avogadro's number (6.022×1023) to obtain the number of atoms. However, when I checked my answers in my textbook, I was wrong by a significant amount.

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