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3 years ago

7. Lawrencium has a half-life of 3.00 minutes. I started with a 100.0 g sample. After 45.0 minutes how

Chemistry

1 answer:

Zinaida [17]3 years ago

6 0

Answer:

N=3.05*10^-3g

Explanation:

Using Ln(No/N)=0.693/t½*t

Ln(No/N)=0.693/3*45

No/N=exp(10.396)

100/exp(10.396)=N

100/32695.7=N

N=3.05*10^-3g

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Natali [406]

Answer:

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Explanation:

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5 0

3 years ago

An unknown compound contains only carbon, hydrogen, nitrogen, and oxygen. Complete combustion of a 2.77 g sample of the compound

alisha [4.7K]

The molecular formula of the unknown compound is determined as C₉H₁₁NO₂.

<h3>Molecular formula of the compound</h3>

The molecular formula is calculated as follows;

CHNO + O₂ ------------> CO₂ + H₂O

Mass of carbon, C: = (6.64 x 12)/44 = 1.81 g in 2.77 g sample

Mass of hydrogen, H: = (1.67 x 2)/18 = 0.186 g in 2.77 g sample

Mass of Nitrogen, N: = (2.77 x 0.143)/1.69 = 0.234 g

Mass of oxygen, O: = 2.77 g - 1.81 g - 0.186 g - 0.234 g = 0.54 g

<h3>molar ratio of the elements: </h3>

C = 1.81 g = 0.15 mol

H = 0.186 g = 0.186 mol

N = 0.234 g = 0.017 mol

O = 0.54 g = 0.0337 mol

divide through with the smallest number of moles (0.017 mol);

C = 9

H = 11

N = 1

O = 2

Molecular formula = C₉H₁₁NO₂

Check the molar mass of the compound = (9 x 12) + (11 x 1) + (14) + (2 x 16) = 165 g/mol

Thus, the molecular formula of the unknown compound is determined as C₉H₁₁NO₂.

Learn more about molecular mass here: brainly.com/question/21334167

#SPJ1

4 0

1 year ago

How does beta decay affect the atomic number?

MA_775_DIABLO [31]

The atomic mass number does<span> not change because a </span>beta<span> particle has a much smaller </span>mass<span> than the </span>atom<span>. The </span>atomic number<span> goes up because a neutron has turned into an extra proton. </span>Beta decay<span> is fundamentally different from alpha </span>decay<span>. An alpha particle is made of two protons and two neutrons.</span>

6 0

3 years ago

This is what your screen should look like. start with Hydrogen -1 and drag 2 neutrons over the to the nucleus. What happens to t

Alekssandra [29.7K]

Answer:

A tritium is produced.

Explanation:

Combining two additional neutrons to the nucleus of the hydrogen atom makes it a tritium, Hydrogen-3.

neutron is designated ¹₀n; this shows a mass number of 1 and no atomic number

Hydrogen-1 is designated as ₁¹H; a mass number of 1 and atomic number of 1. This particle is actually more like a proton.

Combining both:

₁¹H + 2¹₀n → ³₁H

This is a nuclear reaction and in balancing such reaction equation, mass numbers and atomic numbers must be conserved.

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2 years ago

The yttrium- nuclide radioactively decays by electron capture. Write a balanced nuclear chemical equation that describes this pr

evablogger [386]

Answer:

See explanation and image attached

Explanation:

Yttrium has many isotopes, the lowest mass number of Yttrium is 89Y.

Recall that electron capture converts an electron into a proton and then into a neutron with a consequent emission of a neutrino (v).

In electron capture, the mass number of the daughter nucleus remains the same as that of the parent nucleus while the atomic number of the daughter nucleus is less than that of the parent by one unit.

8 0

3 years ago