Chemistry 1

posted by .

I have trouble understanding ratios and relativity so I can't understand how to use atomic mass units. Here is an example from my book:

How many grams of iron would contain the same number of iron atoms as the number of carbon atoms contained in 1.000 g of carbon?

Solution: Iron has an atomic weight of 55.85 meaning that it is 55.85/12.01 times as heavy as carbon. If you have 1 gram of carbon, you would need to weight out:

(55.85 g Fe/ 12.01 g C) x 1.000 g C = 4.650 g Fe

I don't understand why Iron is 5.85/12.01 times as heavy as carbon.

Another related question was: Instead of carbon-12 oxygen-16 was used as the standard for atomic mass units. Using oxygen-16 as the standard what would be the atomic mass of potassium-39?

I have the answers for these questions, but I just don't understand where they come from.

  • Chemistry 1 -

    The atomic mass of Fe is 55.85 but that is a relative number (it is relative to carbon 6C12. The relative mass of carbon is 12.015 (again relative to the 6C12 isotope of carbon). So Fe is 55.85/12.01 times heavier than C.
    There are other ways to work the problem without using ratios and proportion.
    How many moles of C are in 1.000 g C? That will be 1.000/12.01 = 8.33 x 10^-2.

    Since 8.326 x 10^-2 moles Fe and C will contain the same number of atoms, then convert 8.326 x 10^-2 moles Fe to grams.
    g = moles x molar mass = 8.326 x 10^-2 x 55.85 = 4.650 g Fe.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. chemistry

    how many atoms of iron are in .0750 moles of the compound Iron(III) oxide?
  2. Chemistry

    The standard atom for the atomic masses of all the elements is the atom of carbon which has 6 protons and 6 neutrons (12C) and is assigned the atomic mass of exactly 12. Under this standard, the atomic mass of iron, atomic number 26, …
  3. Chemistry

    I have realized I don't understand Avagado's number at all My book shows me this diagram instead of just providing a simple formulas that makes no sense at all here is what I have made sense of so far (6.022 x 10^23 atoms/mol)(mass …
  4. Chemistry

    23. Ductility is the ability to be hammered into sheets.- F?
  5. chemistry

    The atomic mass of iron oxide is 160 atomic mass units. What is the atomic mass of iron if a molecule of iron oxide consists of tow atoms of iron and three atoms of oxgen?
  6. chemistry

    Estimate the number of atoms in 7.827 g of iron using the mass of an atomic mass unit (1.661 x 10^-27). The atomic mass of Fe is 55.85 u.
  7. chemistry

    Estimate the number of atoms in 2.429 g of iron using the mass of an atomic mass unit (1.661 x 10 ^ -27). The atomic mass of Fe is 55.85 u.
  8. chemistry

    How many grams of copper atoms are needed to supply the same number of atoms as does 235 grams of iron?
  9. Chemistry

    A 39 g of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 7.9 grams. What was the percent iron in the sample of ore?
  10. honors chem

    determine the mass of the following example 1.3 x 10^26 iron atoms in iron III oxide, mass of iron II oxide I know this is a 2 part question and you have to use Avogadro's number, but I am clueless as to how to solve it.

More Similar Questions