A sample of pure gold has a mass of 10.2 g. Calculate the number of moles in the sample and gold atoms in the sample.

Explanation:

molecular weight of gold = 197

converting 10.2 g into moles

no of moles = 10.2 / 197

= .0518 moles

one  mole of any element contains 6.02 x 10²³ number of atoms

.0518 moles will contain 6.02 x .0518 x 10²³ atoms of gold

= .311 x 10²³ no of atoms of gold .

= 3.11 x 10²² no of atoms of gold

i only know number one that’s a galaxy

hcl + naoh → h2o + nacl

explanation:

hcl + naoh → h2o + nacl   is the reaction that is correctly balanced.

however, pcl3 + h2 → ph3 +3hcl, 2ca+ 3cl2 → cacl3, and c5h12 + 5o2 → 5co2 + 6h2o are not correctly balanced.