Exam 1: A Very Brief History of Chemistry

Based on the law of Conservation of Mass, 65.4 g of zinc metal reacts with exactly 32.1 g of sulfur to produce zinc sulfide (ZnS)as the only product. What mass of zinc sulfide can be formed from 10.0 g zinc metal? Hint: Consider the ratio of the masses to determine the mass of zinc sulfide.

Why is iron the heaviest element formed in a star prior to the formation of a supernova?

Which one of the statements below is false?

Almost the entire mass of an atom is concentrated in a very large volume outside the center of the atom.

In any given chemical compound, elements are be combined in various non-fixed amounts by mass.

At the nanoscale level, the structures under investigation usually have dimensions of tens to hundreds of atoms.

Which of the following postulates from Dalton's atomic theory are now considered incorrect? I. All atoms of a given element are identical. II. Matter consists of very small particles known as atoms. III. Atoms are indestructible and indivisible.

The atomic mass of naturally occurring copper, which is a mixture of two isotopes, is listed as 63.546 u. This means that ,Hint: Individual atoms have a mass number which is the sum of the protons and neutrons.

A naturally occurring element consists of two isotopes. Calculate the fractional abundances for the two isotopes, if its average atomic mass is 107.87 u. Isotope 1: 106.91 u ---- % Isotope 2: 108.90 u ----- % ,Hint: Set up a weighted average calculation where one percentage is x and the other percentage is (100-x).

The atomic mass of naturally occurring fluorine, which exists in nature as a single isotope, is listed as 18.9984 u. This means that