Question

What is the mass, in grams, of 7.20×1020 molecules of caffeine, c8h10n4o2?

Answer 1

Answer: 0.23 grams

Step-by-step explanation:

According to avogadro's law, 1 mole of every substance weighs equal to its molecular mass and contains avogadro's number
`6.023* 10^(23)` of particles.

To calculate the number of moles, we use the equation:

`\text{Number of moles}=\frac{\text{Given molecules}}{\text{Avogadro's number}}=(7.20* 10^(20))/(6.023* 10^(23))=1.2* 10^(-3)moles`

1 mole of caffeine
`(C_8H_(10)N_4O_2)` weighs = 194 g

`1.2* 10^(-3)` moles of
`(C_8H_(10)N_4O_2)` weigh =
`(194)/(1)* 1.2* 10^(-3)=0.23g`

Thus mass of caffeine
`(C_8H_(10)N_4O_2)` is 0.23 grams.

Answer 2

To determine the mass, you need to know the molecular weight of the c8h10n4o2 . The molecular weight of c8h10n4o2 would be: 8*12 + 10*1 + 4*14 + 2*16= 194g/mol.
To convert the number of molecules into moles, you need to divide it with 6.02 * 10^23. The calculation of the mass of c8h10n4o2 would be:
(7.20×10^20 molecules) /(6.02 * 10^23 molecule/mol) * 194g/mol= 232 * 10^-3 grams= 0.232 grams