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Aloiza [94]
3 years ago
14

Sodium only has one naturally occuring isotope, Na23 , with a relative atomic mass of 22.9898 u. A synthetic, radioactive isotop

e of sodium, Na22 , is used in positron emission tomography. Na22 has a relative atomic mass of 21.9944 u.
A 1.3476 g sample of sodium containing a mixture of Na23 and Na22 has an apparent "atomic mass" of 22.9501 u . Find the mass of Na22 contained in this sample.
Chemistry
1 answer:
alina1380 [7]3 years ago
5 0

The mass of Na22 in the sample is 0.053746 g.

We have a sample with 2 isotopes of sodium. Na22 with a relative atomic mass of 21.9944 u  and Na23 with a relative atomic mass of 22.9898 u. Let "x" be the fractional abundance of Na22 and "1-x" the fractional abundance of Na23. If the apparent atomic mass is 22.9501 u, we can state the following expression.

mNa22 \times x + mNa23 \times (1-x) = 22.9501u\\21.9944u \times x + 22.9898u \times (1-x) = 22.9501u\\x=0.039883

The mass of the sample is 1.3476 g. We can find the mass of Na22 in the sample by multiplying it by its fractional abundance.

1.3476g \times 0.039883 = 0.053746 g

The mass of Na22 in the sample is 0.053746 g.

You can learn more about isotopes here: brainly.com/question/21536220

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What is the mass of an element with 15 protons, 13 electrons, and 11 neutrons? *
RSB [31]

Answer:

The mass of the element is 26.20 amu

Explanation:

In this question, we are asked to calculate the mass of an element with 15 protons, 13 electrons and 11 neutrons

To calculate the atomic mass of the element, we take into consideration the masses of the individual sub atomic particles

Electrons have 0 atomic mass unit(their masses are negligible) we have no business here, Protons have a mass of

1.00727647 amu, while the mass of neutron is 1.0086654 amu

The mass of 15 protons is thus 15 * 1.00727647 = 15.10914705 amu

The mass of 11 neutrons is 11 * 1.0086654 =

11.0953194 amu

Adding this together, we have ; 11.0953194 + 15.10914705 = approximately 26.20 amu

6 0
4 years ago
A student conducts an experiment to determine how the temperature of water affects the time for sugar to dissolve. In each trial
V125BC [204]

The fact that the student used different amount of water (another independent variable) is wrong with the experimental design

WHAT ARE THE COMPONENTS OF AN EXPERIMENT?

  • An experiment aims at solving a scientific problem or answering a scientific question. An experiment should contain a variable being changed called INDEPENDENT VARIABLE and a variable being measured called DEPENDENT VARIABLE.

  • In an ideal experiment, only one independent variable should be used while every other variable should be kept constant. This is done so as not to affect the result of the experiment.

In the experiment conducted by the student in this question, two independent variables were used i.e. the different amount of water and the different temperatures. This is what is wrong about the experimental design.

  • In a nutshell, the fact that two independent variables were used by the student is what is wrong about the experimental design.

Learn more at: brainly.com/question/967776

8 0
3 years ago
The atomic mass of an element is found by which of the following methods?
Lera25 [3.4K]
On the periodic table it is the number on the bottom of the element. 
<span>If you know the amount of neutrons you can add it to the number of protons to find the atomic mass NUMBER, which is a good approximate of the atomic mass. </span>
8 0
4 years ago
When 100. mL of 6.00 M HCl is diluted to 300. mL, the final concentration is ________.
Marat540 [252]

Answer:

2.00 M

Explanation:

The concentration of a solution is given by

M=\frac{m}{V}

where

m is the mass of solute

V is the volume of the solution

At the beginning, the solution has:

M = 6.00 M is the concentration

V = 100 mL = 0.1 L is the volume

So the mass of solute (HCl) is

m=MV=(6.00)(0.1)=0.6g

Then, the HCL is diluted into a solution with volume of

V = 300 mL = 0.3 L

Therefore, the final concentration is:

M=\frac{m}{V}=\frac{0.6}{0.3}=2.00 M

3 0
4 years ago
Read 2 more answers
assuming the magnesium ribbon wasn't sufficiently polished to remove a coating of magnesium oxie on the surface. how would this
Ira Lisetskai [31]

The magnesium ribbon wasn't sufficiently polished to remove a coating of magnesium oxie on the surface. how would this affect the volume of hydrogen gas produced? would this error cause the gas constant to be overestimated, underestimated, or remain unaffected?

1. Since, the magnesium ribbon wasn’t sufficiently polished to remove a coating of magnesium oxide on surface, the actual mass of magnesium taken will be less (as it also contains magnesium oxide). Hence, the number of moles of magnesium reacted and the number of moles of hydrogen produced will be less.  Due to this, the volume of hydrogen gas produced will be less and the gas constant will be underestimated. R=\frac {PV}{nT} . Here n is calculated from weight of Mg taken but V is measured. Thus values of n will be same but the value of V will be lower. Hence, the value of R will be lower.

2. When droplets of water are remaining in the eudiometer tube, there volume will be added to the volume of hydrogen and the measured volume of hydrogen will be more than actual volume. Due to this, the value of the gas constant will be overestimated.

3. When small amount of hydrogen dissolves in water, the measured volume of hydrogen will be lower than the actual volume. This will underestimate the value of the gas constant.

4. When the temperature of the gas was underestimated, the value of the gas constant will be overestimated as the gas constant is inversely proportional to the temperature.            {PV}

                                                           R=

                                                                   {nT}.

Magnesium is a chemical detail with the symbol Mg and atomic number 12. it is a glittery gray solid which stocks many bodily and chemical residences with the alternative 5 alkaline earth metals (institution 2 of the periodic desk).

This element is produced in huge, growing old stars from the sequential addition of three helium nuclei to a carbon nucleus. whilst such stars explode as supernovas, a lot of the magnesium is expelled into the interstellar medium wherein it may recycle into new big name structures. Magnesium is the eighth maximum abundant element inside the Earth's crust and the fourth maximum not unusual detail in the Earth (after iron, oxygen and silicon), making up 13% of the planet's mass and a big fraction of the planet's mantle. it's miles the 0.33 maximum abundant detail dissolved in seawater, after sodium and chlorine.

Learn more about Magnesium here:-brainly.com/question/25860912

#SPJ4

8 0
2 years ago
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