Question

1. the element copper has naturally occurring isotopes with mass numbers of 63 and 65. the relative abundance and atomic masses are 69.2% for mass = 62.93 amu, and 30.8% for mass = 64.93 amu. calculate the average atomic mass of copper.
2. calculate the atomic mass of bromine. the two isotopes of bromine have atomic masses and relative abundance of 78.92 amu (50.69%) and 80.92 amu (49.31%).

Explanation:

Step1: Convert percentages to decimals

69.2% = 0.692, 30.8% = 0.308

Step2: Calculate contribution of each isotope

(62.93 amu × 0.692) + (64.93 amu × 0.308) ≈ 43.55 amu + 20.00 amu = 63.55 amu

Step3: Convert percentages to decimals for Br

50.69% = 0.5069, 49.31% = 0.4931

Step4: Calculate contribution of each Br isotope

(78.92 amu × 0.5069) + (80.92 amu × 0.4931) ≈ 40.00 amu + 39.90 amu = 79.90 amu

Answer:

1. 63.55 amu
2. 79.90 amu