Help with chemistry?

[BeautifulxxLie]

I am doing my chemistry homework and I do not understand how to do the following:

-Determine the % of iron in the mineral Goethite (HFeO2).
-How many mg of iodine are carried by each mg of the thyroid hormone, thyoxine (C15H11NO4I4)?

I'm not asking for the answers, I just want to know HOW to do the examples. Any help would be much appreciated.

[timothy y]

Well this is all sort of advanced for me but I'll try

1. Geothite is made up of Hydrogen, iron and oxygen. The oxygen is 2 molecules. The total no. of molecules is 5. The no. of molecules the iron has is 1. So you just do 1/5* 100 to get the answer

2. Ermm Thyoxine is made of oxygen and something else. The chemical symbol of iodine is I. Thats all i can help u with

Dun blame me if I get it wrong

[AY NAKO]

For both questions you need the molecular weight of each atom involved within each compound, AND the molecular weight of the compound itself.

For the first one, take the molecular weight of iron and divide it by the molecular weight of goethite, then multiply by 100 to get the percentage.

For the second one, assume that there is 1 mol of thyroxine (hehe, not "thyoxine," just to point it out). Take the number of grams of iodine in 1 mol (the number would be the same as the molecular weight, except the units are "g" instead of "g/mol"), convert it to milligrams (1 gram = 1000 milligrams). Multiply it by 4 because there's 4 iodines involved in thyroxine. For thyroxine, you just have to find the number of grams in 1 mol. Finally, divide the mg of iodine by the mg of thyroxine. That will be your answer.

If that's confusing, here's an example. Let's say there's 5 grams of A in compound B, or 5000 milligrams. The molecular weight of compound B is 10 g/mol. In one mole of B, there are 10 grams of B, or 10,000 milligrams. 5000 mg divided by 10,000 mg is 0.5 mg. Therefore, there is 0.5 mg of A in each mg of compound B.

If you're still confused, just say so in additional details and I'll try to be more clear. Hope this helps!

[lover2]

idk wat my teachers do is gives us there phone #s so y not call if you have it or get it