6. calculate the atomic mass of copper if copper - 63 is 69.17% abundant and copper - 65 is 30.83%…

6. calculate the atomic mass of copper if copper - 63 is 69.17% abundant and copper - 65 is 30.83% abundant.\n7. boron exists in two isotopes, boron - 10 and boron - 11. based on the atomic mass, which isotope should be more abundant?\n8. lithium - 6 is 4% abundant and lithium - 7 is 96% abundant. what is the average mass of lithium?\n9. iodine is 80% ¹²⁷i, 17% ¹²⁶i, and 3% ¹²⁸i. calculate the average atomic mass of iodine.\n10. the natural abundance for boron isotopes is 19.9% ¹⁰b and 80.1% ¹¹b. calculate boron’s atomic mass.\n11. hydrogen is 99% ¹h, 0.8% ²h, and 0.2% ³h. calculate its average atomic mass.\n12. rubidium is a soft, silvery - white metal that has two common isotopes, ⁸⁵rb and ⁸⁷rb. if the abundance of ⁸⁵rb is 80.2% and the abundance of ⁸⁷rb is 19.8%, what is the average atomic mass of rubidium?\n13. what is the atomic mass of hafnium if, out of every 100 atoms, 5 have a mass of 176, 19 have a mass of 177, 27 have a mass of 178, 14 have a mass of 179, and 35 have a mass of 180.0?

6. calculate the atomic mass of copper if copper - 63 is 69.17% abundant and copper - 65 is 30.83% abundant.\n7. boron exists in two isotopes, boron - 10 and boron - 11. based on the atomic mass, which isotope should be more abundant?\n8. lithium - 6 is 4% abundant and lithium - 7 is 96% abundant. what is the average mass of lithium?\n9. iodine is 80% ¹²⁷i, 17% ¹²⁶i, and 3% ¹²⁸i. calculate the average atomic mass of iodine.\n10. the natural abundance for boron isotopes is 19.9% ¹⁰b and 80.1% ¹¹b. calculate boron’s atomic mass.\n11. hydrogen is 99% ¹h, 0.8% ²h, and 0.2% ³h. calculate its average atomic mass.\n12. rubidium is a soft, silvery - white metal that has two common isotopes, ⁸⁵rb and ⁸⁷rb. if the abundance of ⁸⁵rb is 80.2% and the abundance of ⁸⁷rb is 19.8%, what is the average atomic mass of rubidium?\n13. what is the atomic mass of hafnium if, out of every 100 atoms, 5 have a mass of 176, 19 have a mass of 177, 27 have a mass of 178, 14 have a mass of 179, and 35 have a mass of 180.0?

Answer

Explanation:

Step1: Recall the formula for average atomic mass

The average atomic mass ($A_{avg}$) of an element with isotopes $i$ is given by $A_{avg}=\sum_{i} (m_i\times p_i)$, where $m_i$ is the mass of the $i$-th isotope and $p_i$ is its relative - abundance.

Step2: Calculate the atomic mass of hafnium

For hafnium:

  • For the first isotope with mass $m_1 = 176$ and abundance $p_1=\frac{5}{100}=0.05$: $m_1\times p_1=176\times0.05 = 8.8$
  • For the second isotope with mass $m_2 = 177$ and abundance $p_2=\frac{19}{100}=0.19$: $m_2\times p_2=177\times0.19 = 33.63$
  • For the third isotope with mass $m_3 = 178$ and abundance $p_3=\frac{27}{100}=0.27$: $m_3\times p_3=178\times0.27 = 48.06$
  • For the fourth isotope with mass $m_4 = 179$ and abundance $p_4=\frac{14}{100}=0.14$: $m_4\times p_4=179\times0.14 = 25.06$
  • For the fifth isotope with mass $m_5 = 180$ and abundance $p_5=\frac{35}{100}=0.35$: $m_5\times p_5=180\times0.35 = 63$

Step3: Sum up the products

$A_{avg}=8.8 + 33.63+48.06+25.06+63$ $A_{avg}=178.55$ amu

Answer:

178.55 amu