Question

A sample of glucose, C6H12O6, contains 1.200×1021 carbon atoms.

A)How many atoms of hydrogen does it contain?

D)What is the mass of this sample in grams?

Answer 1

A)
In C6H12O6,
number of H = 2*number of C
= 2*1.200*10^21
= 2.400*10^21 carbon atoms
Answer: 2.400*10^21 carbon atoms

D)
1 C6H12O6 cntains 6 carbon atom
So,
number of C6H12O6 = number of C atoms / 6
= (1.200*10^21) / 6
= 2.00*10^20

moles of C6H12O6 = number of molecules / Avogadro's number
= (2.00*10^20)/(6.022*10^23)
= 3.32*10^-4 moles

Molar mass of C6H12O6,
MM = 6*MM(C) + 12*MM(H) + 6*MM(O)
= 6*12.01 + 12*1.008 + 6*16.0
= 180.156 g/mol

mass of C6H12O6,
m = number of mol * molar mass
= 3.32*10^-4 mol * 180.156 g/mol
= 5.98*10^-2 g
Answer: 5.98*10^-2 g