Question

a sample of a pure element is analyzed using a mass spectrometer to produce the graph provided. estimate the atomic masses and relative abundances of the isotopes shown on the graph, ordered from lowest atomic mass to highest. answers have a 5% tolerance to allow for estimation. atomic mass of isotope (u) relative abundance (%) what is the average relative atomic mass of the element in the sample? assuming that the sample represents natural abundances found on earth, which element is the sample made up of? relative abundance (%) 0 10 20 30 40 50 60 70 atomic mass (u) 67 68 69 70 71 72

Explanation:

Step1: Identify isotopes and abundances

From the graph, isotope 1: atomic mass ≈ 69 u, relative abundance ≈ 60% (0.6); isotope 2: atomic mass ≈ 71 u, relative abundance ≈ 40% (0.4).

Step2: Calculate average atomic mass

Use formula: \( \text{Average Mass} = (m_1 \times a_1) + (m_2 \times a_2) \)
\( = (69 \times 0.6) + (71 \times 0.4) \)
\( = 41.4 + 28.4 \)
\( = 69.8 \) u (≈ 70 u with tolerance, but precise is 69.8).

Step3: Identify the element

Average atomic mass ~69.8 u matches Gallium (Ga) or Zinc? Wait, no—wait, 69 u (Cu? No, Cu is ~63, 65). Wait, maybe Gallium? Wait, no, let's check: Isotopes of Ga: 69 (60.1%) and 71 (39.9%), average ~69.72 u, which matches. So element is Gallium.

Answer:

Average relative atomic mass: \( \boldsymbol{69.8} \) u (or ~70 u).
Element: Gallium (Ga).