Question

part a
on a mission to a newly discovered planet, an astronaut finds copper abundances of 69.15% for ^63cu and 30.85% for ^65cu. what is the atomic mass of copper for this location?
the mass of ^63cu is 62.9300 amu. the mass of ^65cu is 64.9200 amu.
express your answer to two decimal places, and include the appropriate units.
part b
the astronaut then measures the abundance of strontium on the new planet, obtaining the following results:
what is the atomic mass of strontium for this planet?
express your answer to two decimal places, and include the appropriate units.

Explanation:

Part A

Step1: Calculate the contribution of \(^{63}\text{Cu}\)

The contribution of \(^{63}\text{Cu}\) is calculated by multiplying its mass by its abundance.

$$62.9300\times\frac{69.15}{100}=62.9300\times0.6915 = 43.52$$

Step2: Calculate the contribution of \(^{65}\text{Cu}\)

The contribution of \(^{65}\text{Cu}\) is calculated by multiplying its mass by its abundance.

$$64.9200\times\frac{30.85}{100}=64.9200\times0.3085=20.03$$

Step3: Find the atomic mass of copper

Add the contributions of \(^{63}\text{Cu}\) and \(^{65}\text{Cu}\)

$$43.52 + 20.03=63.55$$

Answer:

\(63.55\) amu

Part B

Step1: Calculate the contribution of \(^{86}\text{Sr}\)

The contribution of \(^{86}\text{Sr}\) is calculated by multiplying its mass by its abundance.

$$85.91\times\frac{9.46}{100}=85.91\times0.0946 = 8.13$$

Step2: Calculate the contribution of \(^{87}\text{Sr}\)

The contribution of \(^{87}\text{Sr}\) is calculated by multiplying its mass by its abundance.

$$86.91\times\frac{7.00}{100}=86.91\times0.07 = 6.08$$

Step3: Calculate the contribution of \(^{88}\text{Sr}\)

The contribution of \(^{88}\text{Sr}\) is calculated by multiplying its mass by its abundance.

$$87.91\times\frac{83.54}{100}=87.91\times0.8354 = 73.47$$

Step4: Find the atomic mass of strontium

Add the contributions of \(^{86}\text{Sr}\), \(^{87}\text{Sr}\) and \(^{88}\text{Sr}\)

$$8.13+6.08 + 73.47=87.68$$