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tatyana61 [14]
2 years ago
14

Imagine you have 50,000 atoms of uranium-238. If U-238 has a half-life of 4.5 billion years, how many U-238 atoms will be left a

fter 4.5 billion years
Chemistry
2 answers:
Lelechka [254]2 years ago
8 0

Answer:25,000

Explanation:

I took the test

Mrac [35]2 years ago
8 0

25000 molecules of U-238 element will be left after 4.5 billion years.

<h2>What is half life of radioactive element?</h2>

<h3>Half life of radioactive element</h3>

Half-life of radioactive elements refers to the time interval needed for one-half of the atomic nuclei of a radioactive sample to decay. The change occurs in the radioactive element into other nuclear species by emitting particles and energy.

Radioactive decay reduces the number of radioactive nuclei up to half of its original value or molecules so we can conclude that 25000 molecules of U-238 element will be left after 4.5 billion years.

Learn more about radioactive here: brainly.com/question/1236735

Learn more: brainly.com/question/26182507

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Determine which of the following pairs of reactants will result in a spontaneous reaction at 25°C. None of the above pairs will
Alla [95]

Answer:

Only Fe^{3+}+Mg gives spontaneous reaction.

Explanation:

A redox reaction will be spontaneous if standard reduction potential (E^{0}) of the reaction is positive. Because it leads to negative standard gibbs free energy change (\Delta G^{0}), which is a thermodynamic condition for spontaneity of a reaction.

E^{0}=E^{0}(reduction)-E^{0}(oxidation)

Where E^{0}(reduction) and E^{0}(oxidation) represents standard reduction potential of reduction half cell and standard reduction potential of oxidation half cell.

(1) Oxidation:         Mg-2e^{-}\rightarrow Mg^{2+} ;  E_{Mg^{2+}\mid Mg}^{0}=-2.38V

Reduction:         Fe^{3+}+3e^{-}\rightarrow Fe ; E_{Fe^{3+}\mid Fe}^{0}=-0.04V

So, E^{0}=E_{Fe^{3+}\mid Fe}^{0}-E_{Mg^{2+}\mid Mg}^{0}=(-0.04+2.38)V=2.34V

Hence this pair will give spontaneous reaction.

(2) Similarly as above, E^{0}=E_{Pb^{2+}\mid Pb}^{0}-E_{Au^{+}\mid Au}^{0}=(-0.13-1.69)V=-1.82 V

Hence this pair will give non-spontaneous reaction.

(3) Similarly as above, E^{0}=E_{Ag^{+}\mid Ag}^{0}-E_{Br_{2}\mid Br^{-}}^{0}=(0.80-1.07)V=-0.27 V

Hence this pair will give non-spontaneous reaction.

(4)  Similarly as above, E^{0}=E_{Li^{+}\mid Li}^{0}-E_{Cr^{3+}\mid Cr}^{0}=(-3.04+0.74)V=-2.30 V

Hence this pair will give non-spontaneous reaction.

6 0
3 years ago
What is the molarity of a nitric acid solution if 43.13 mL 0.1000 M KOH solution is needed to neutralize 30.00 mL of the acid so
Leno4ka [110]

Answer:

0.144M

Explanation:

First, let us write a balanced equation for the reaction. This is illustrated below:

HNO3 + KOH —> KNO3 + H20

From the equation,

nA = 1

nB = 1

From the question given, we obtained the following:

Ma =?

Va = 30.00mL

Mb = 0.1000M

Vb = 43.13 mL

MaVa / MbVb = nA/nB

Ma x 30 / 0.1 x 43.13 = 1

Cross multiply to express in linear form

Ma x 30 = 0.1 x 43.13

Divide both side by 30

Ma = (0.1 x 43.13) /30 = 0.144M

The molarity of the nitric acid is 0.144M

8 0
3 years ago
An element has 3 electrons, 3 protons and 4 neutrons. What will be its atomic number and mass number? (​
stiv31 [10]

Answer:

its atomic number will be 3 and it's mass number will be 7. it is lithium

8 0
2 years ago
Is potassium fluoride a covalent bond or ionic bond
Ivahew [28]

It's an ionic bond! Potassium is a cation, or a metal with a positive charge, and fluoride is an anion, or a nonmetal with a negative charge.

A covalent bond is the bond between two nonmetals.

Hope this helped!

7 0
4 years ago
Read 2 more answers
Question: Draw a valid Lewis structure for the molecule CH3NO in which there are no nonzero formal charges on any of the atoms.
iVinArrow [24]

The mentioned molecule with formula, CH₃NO where no bond is found between N and O can be depicted as formamide is shown in the attachment below.  

The formal charges = Number of valence electrons for the atom (V) - the number of electrons in lone pairs (N) - 1/2 (number of electrons in bond pairs, B)

FC = V - N - B/2

Thus, there is a need to calculate valence electrons, electrons in lone pairs, and the number of electrons in bond pairs for each atom in the mentioned molecule.  

V or valence electrons on C = 4e, on H = 1e, on N = 5e, and on O = 6e.  

N or electrons in lone pairs on C = 0e, on H = 0e, on N = 2e, and on O = 4e.  

B or number of electrons in bond pairs for C = 8e, for H = 2e, for N = 6e, and for O = 4e.  

Thus, the formal charges for each will be,  

C = 4 - 0 - (8/2) = 0

H = 1 - 0 - (2/2) = 0

N = 5 - 2 - (6/2) = 0

O = 6 - 4 - (4/2) = 0

Lewis dot structure for the given molecule is given in the attachment below:


3 0
3 years ago
Read 2 more answers
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