Question

1. A sample of gold (Au) has a mass of 35.12 g.

a. Calculate the number of moles of gold (Au) in the sample and record in
Table 1. Show your work.
b. Calculate the number of atoms of gold (Au) in the sample and record
in Table 1. Show your work.
2. A sample of table sugar (sucrose, C12H22O11) has a mass of 1.202 g.
a. Calculate the number of moles of C12H22O11 contained in the sample
and record in Table 1. Show your work.

Answer 1

o solve this, first convert the sample into moles.

35.12g Au * (1mol/197g) = 0.18 mol Au

Then, using this mole value, convert into atoms by multiplying by Avogadro's number:

0.18 mol * (6.022 * 10^23 atoms/1 mol) = 1.08*10^23 atom

2. Again, start by converting to moles using the molar mass:

12 mol C = 12*12 = 144g
22 mol H = 22*1 = 22g
11 mol O = 11*16 = 176 g
---------------------------------------...
C12H22011 = 144+22+176 = 342g/mol

Then use that value to convert the mass to moles.
2
1.202g C12H22O11 * (1mol / 342g) = 3.5*10^-3 mol C12H22O11


b. 3.5*10^-3 * (144/342) = 1.5*10^-3mol C
etc.
follow the same procedure as b, but with atom value