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The element europium exists in nature as two isotopes: \({ }^{151} \mathrm{Eu}\) has a mass of \(150.9196 \mathrm{u}\) and \({ }^{153} \mathrm{Eu}\) has a mass of \(152.9209 \mathrm{u}\). The average atomic mass of europium is \(151.96 \mathrm{u} .\) Calculate the relative abundance of the two europium isotopes.

Short Answer

Expert verified
The relative abundance of \({ }^{151} \mathrm{Eu}\) is approximately 47.97% and the relative abundance of \({ }^{153} \mathrm{Eu}\) is approximately 52.03%.

Step by step solution

01

Define the variables for the relative abundance of each isotope

Let x be the relative abundance of \({ }^{151} \mathrm{Eu}\) and y be the relative abundance of \({ }^{153} \mathrm{Eu}\). Since these are the only two isotopes, their relative abundances sum up to 100% or 1, so we can write: x + y = 1
02

Set up the equation relating average atomic mass and individual atomic masses

Using the given data and the relationship between the average atomic mass and the individual atomic masses with their relative abundance, the equation is: 151.96 = (150.9196 × x) + (152.9209 × y)
03

Solve the equations for the relative abundance of each isotope

Now we have a system of two linear equations with two variables, x and y: 1. x + y = 1 2. 151.96 = (150.9196 × x) + (152.9209 × y) From equation (1), we can obtain x as follows: x = 1 - y Now, substitute x in equation (2): 151.96 = (150.9196 × (1 - y)) + (152.9209 × y) Expand and rearrange to solve for y: 151.96 = 150.9196 - 150.9196y + 152.9209y 151.96 = 150.9196 + 2.0013y Now, solve for y: 2.0013y = 151.96 - 150.9196 y = \(\frac{1.0404}{2.0013}\) y ≈ 0.5203 Now, substitute the value of y back into the equation for x: x = 1 - 0.5203 x ≈ 0.4797 Thus, the relative abundance of \({ }^{151} \mathrm{Eu}\) (x) is approximately 47.97% and the relative abundance of \({ }^{153} \mathrm{Eu}\) (y) is approximately 52.03%.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Isotopes
Isotopes are variations of the same chemical element that have identical numbers of protons but different numbers of neutrons. This results in them having different atomic masses. Despite these differences, isotopes of an element behave very similarly in chemical reactions. It's like identical twins - they look the same but might have slight differences you can't easily see. Isotopes are naturally occurring, and many elements can have several isotopes. Some are stable, while others might be radioactive. It's important to understand isotopes because they can significantly affect the element's average atomic mass, which is a weighted average based on the isotope's natural abundance.
Average Atomic Mass
The average atomic mass of an element is the weighted average of all the isotopes' atomic masses that occur naturally. It reflects the mass of an element's atoms considering the isotopic composition. The average atomic mass isn't just a simple arithmetic mean because it takes into account the relative abundance of each isotope. To compute it, you multiply the atomic mass of each isotope by its fractional abundance (relative abundance expressed as a decimal), and then sum these values. For example, if you have two isotopes with masses and abundances, the formula is:\[\text{Average Atomic Mass} = (\text{mass of \( ^{151} Eu\)} \times x) + (\text{mass of \( ^{153} Eu\)} \times y)\]where \( x \) and \( y \) are the relative abundances of the isotopes, respectively. The result gives one value representing the element's average mass, observable when measuring a significant sample of atoms.
Linear Equations
Linear equations are mathematical statements where variables are related in a linear manner. This means that any variable can be solved without involving exponents or products of variables – each variable is to the first power. Linear equations usually appear in the form of \( ax + b = c \), where \( a \), \( b \), and \( c \) are numbers, and \( x \) is the variable.For solving problems involving isotopic abundances, linear equations help express relationships between multiple isotopes' relative abundances and their contributions to the average atomic mass. In our case with europium isotopes, we use two linear equations to solve for the variables \( x \) and \( y \), which represent the relative abundances of \( ^{151} Eu \) and \( ^{153} Eu \) respectively:
  • Equation 1: \( x + y = 1 \)
  • Equation 2: \( 151.96 = (150.9196 \times x) + (152.9209 \times y) \)
These equations make it relatively straightforward to solve for the unknown values using simple algebraic techniques.
Europium Isotopes
Europium, a rare earth element, naturally occurs with two main isotopes: \( ^{151} \text{Eu} \) and \( ^{153} \text{Eu} \). Each has its unique mass due to different numbers of neutrons, but both isotopes contribute to europium's chemical properties.Knowing the relative abundance of these isotopes is important for accurately calculating the average atomic mass of europium. The specific masses are \( 150.9196 \text{u} \) and \( 152.9209 \text{u} \) for \( ^{151} \text{Eu} \) and \( ^{153} \text{Eu} \) respectively, and the average atomic mass of europium is known to be \( 151.96 \text{u} \).Incorporating these masses into equations allows us to determine how each isotope is represented in nature, which leads to valuable insights not only in chemistry but also in various applications that utilize isotopic differences, like radiometric dating and nuclear medicine.

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Most popular questions from this chapter

Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid-fuel rocket motors. The reaction is $$ \mathrm{Fe}_{2} \mathrm{O}_{3}(s)+2 \mathrm{Al}(s) \longrightarrow 2 \mathrm{Fe}(l)+\mathrm{Al}_{2} \mathrm{O}_{3}(s) $$ What masses of iron(III) oxide and aluminum must be used to produce \(15.0 \mathrm{~g}\) iron? What is the maximum mass of aluminum oxide that could be produced?

An iron ore sample contains \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) plus other impurities. \(\mathrm{A}\) \(752-\mathrm{g}\) sample of impure iron ore is heated with excess carbon, producing \(453 \mathrm{~g}\) of pure iron by the following reaction: $$ \mathrm{Fe}_{2} \mathrm{O}_{3}(s)+3 \mathrm{C}(s) \longrightarrow 2 \mathrm{Fe}(s)+3 \mathrm{CO}(g) $$ What is the mass percent of \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) in the impure iron ore sample? Assume that \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) is the only source of iron and that the reaction is \(100 \%\) efficient.

You take \(1.00 \mathrm{~g}\) of an aspirin tablet (a compound consisting solely of carbon, hydrogen, and oxygen), burn it in air, and collect \(2.20 \mathrm{~g} \mathrm{CO}_{2}\) and \(0.400 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}\). You know that the molar mass of aspirin is between 170 and \(190 \mathrm{~g} / \mathrm{mol}\). Reacting 1 mole of salicylic acid with 1 mole of acetic anhydride \(\left(\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{3}\right)\) gives you 1 mole of aspirin and 1 mole of acetic acid \(\left(\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}_{2}\right.\) ). Use this information to determine the molecular formula of salicylic acid.

Ammonia is produced from the reaction of nitrogen and hydrogen according to the following balanced equation: $$ \mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g) \longrightarrow 2 \mathrm{NH}_{3}(g) $$ a. What is the maximum mass of ammonia that can be produced from a mixture of \(1.00 \times 10^{3} \mathrm{~g} \mathrm{~N}_{2}\) and \(5.00 \times 10^{2} \mathrm{~g} \mathrm{H}_{2} ?\) b. What mass of which starting material would remain unreacted?

Coke is an impure form of carbon that is often used in the industrial production of metals from their oxides. If a sample of coke is \(95 \%\) carbon by mass, determine the mass of coke needed to react completely with \(1.0\) ton of copper(II) oxide. $$ 2 \mathrm{CuO}(s)+\mathrm{C}(s) \longrightarrow 2 \mathrm{Cu}(s)+\mathrm{CO}_{2}(g) $$

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