The atomic mass is the average of the isotopes of the element meaning most averages of isotopes will not be whole numbers
1) You need to use the atomic mass of copper.
You can find it in a periodic table. It is 63.546 amu.
2) The atomic mass is the weigthed mass of the different isotopes.
This is, the atomic mass of one element is the atomic mass of each isotope times its corresponding abundance:
=> atomic mass of the element = abundance isotope 1 * atomic mass isotope 1 + abundance isotope 2 * atomic mass isotope 2 + ....+abundance isotope n * atomic mass isotope n.
3) The statement tells there are two isotopes so the abundance of one is x and the abundance of the other is 1 - x
=> 63.546 amu = x * 62.9296 amu + (1-x)*64.9278
=> 63.546 = 62.9296x + 64.9278 - 64.9278x
=> 64.9278x - 62.9296 = 64.9278 - 63.546
=> 1.9982x = 1.3818
=> x = 1.3818 / 1.9982 = 0.6915 = 69.15%
=> 1 - x = 1 - 0.6915 = 0.3085 = 30.85%
Answer:
Cu-63 69.15%;
Cu-65 : 30.85%
Answer:
24 mol Cu
General Formulas and Concepts:
<u>Chemistry</u>
Explanation:
<u>Step 1: Define</u>
RxN: 2Cu (s) + O₂ (g) → 2CuO (s)
Given: 12 moles O₂
<u>Step 2: Stoichiometry</u>
<u />
= 24 mol Cu
<u>Step 3: Check</u>
<em>We are given 2 sig figs.</em>
Our final answer is in 2 sig figs, so no need to round.
