Question

copper (symbol cu) has two naturally occurring isotopes, cu - 63 and cu - 65. the relative atomic mass of copper is 63.55. * (0.5 points)
what is the percent abundance of the isotope copper - 63? round your answer to one decimal place.
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9
copper (symbol cu) has two naturally occurring isotopes, cu - 63 and cu - 65. the relative atomic mass of copper is 63.55. * (0.5 points)
what is the percent abundance of the isotope copper - 65? round your answer to one decimal place.
enter your answer

Explanation:

Step1: Let the percent abundance of Cu - 63 be $x$.

Then the percent abundance of Cu - 65 is $1 - x$.

Step2: Set up the equation for relative atomic mass.

The relative atomic mass of an element is the weighted - average of the masses of its isotopes. So, $63x+65(1 - x)=63.55$.

Step3: Expand and simplify the equation.

$63x + 65-65x=63.55$. Combine like terms: $65 - 2x=63.55$.

Step4: Solve for $x$.

First, subtract 65 from both sides: $-2x=63.55 - 65=-1.45$. Then divide both sides by - 2: $x=\frac{1.45}{2}=0.725$.

Step5: Convert $x$ to a percentage.

Multiply $x$ by 100: $x = 72.5\%$. This is the percent abundance of Cu - 63.

Step6: Calculate the percent abundance of Cu - 65.

Since the sum of the percent abundances of all isotopes is 100%, the percent abundance of Cu - 65 is $100 - 72.5 = 27.5\%$.

Answer:

Percent abundance of Cu - 63: 72.5%
Percent abundance of Cu - 65: 27.5%