chemistry basic calculation

Question

there is about 50.10⁹ of gold atoms in one drop of a sea water. how many grams of gold can be obtained from 1 tonne of sea water, if we know that the mass of 1 drop is 33 mg.

Answer 1

For this problem we are going to have to convert from the ton (I'm assuming it is a metric ton) of water into mg of water. For this we are going to have to convert from ton to kg and from there to g, then convert to mg, and using the ratio that one drop of water weighs 33mg convert to drops of water. It will look something like this

1 ton * (1000kg/ton)*(1000g/kg)*(1000mg/g)(drop/33)=3.03*10^7 drops of water.

Once we have the drops of water we can convert from drops of water to # of gold atoms. Convert from # of gold atoms to mols of gold using avagardo's number; then finally convert from mols of gold to grams of gold using molar mass . It will look something like this

3.03*10^7 drops of water *(50*10^9) atoms/drop of water)*(mol/6.022*10^23 atoms)*(196.97g/mol)

And then it's just a matter of multiplying and dividing, let me know if you have any questions or concerns for how I showed the work.