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3 years ago

7

suppose you mix two colorless liquids together and a green solid settles to the bottom of the container. explain why you might b

e confident that a chemical change has taken place.

1 answer:

Andrew [12]3 years ago

6 0

Because a unexpected color change has taken place also a precipitate was formed

You might be interested in

antimony has two naturally occuring isotopes, sb121sb121 and sb123sb123 . sb121sb121 has an atomic mass of 120.9038 u120.9038 u

Luda [366]

Considering the definition of atomic mass, isotopes and atomic mass of an element, sb121 has a percent natural abundance of 0.5726 or 57.26% and sb123 has a percent natural abundance of 0.4284 or 42.84%.

<h3>Definition of atomic mass</h3>

The atomic mass is obtained by adding the number of protons and neutrons in a given nucleus of a chemical element.

<h3>Definition of isotope</h3>

Isotopes are the chemical elements in which atomic numbers are the same, but the number of neutrons is different.

<h3>Definition of atomic mass</h3>

The atomic mass of an element is the weighted average mass of its natural isotopes.

This is, the atomic masses of elements are usually calculated as the weighted average of the masses of the different isotopes of each element, considering the relative abundance of each of them.

<h3>Percent natural abundance of each isotope</h3>

In this case, antimony has two naturally occuring isotopes, sb121 and sb123. You know:

sb121 has an atomic mass of 120.9038 u.
sb121 has a percent natural abundance of x.
sb123 has an atomic mass of 122.9042 u.
sb123 has a percent natural abundance of 1 -x (or, what is the same, the abundance is 100% - x%, since both isotopes form 100% of the element.)
Antimony has an average atomic mass of 121.7601 u

The average mass of antimony is expressed as:

121.7601 u= 120.9038 u x + 122.9042 u× (1 -x)

Solving:

121.7601 u= 120.9038 u x + 122.9042 u - 122.9042 u x

121.7601 u - 122.9042 u= 120.9038 u x - 122.9042 u x

(-1.1441 u)= (-2.0014) x

(-1.1441 u)÷ (-2.0014)= x

<u><em>0.5726= x or 57.26%</em></u>

So, 1 -x= 1- 0.5716 → <u><em>1-x= 0.4284 or 42.84%</em></u>

<u><em /></u>

Finally, sb121 has a percent natural abundance of 0.5726 or 57.26% and sb123 has a percent natural abundance of 0.4284 or 42.84%.

Learn more about average atomic mass:

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5 0

2 years ago

An atom of lithium (Li) forms an ionic bond with an atom of chlorine (Cl) to form lithium chloride. How are the valence electron

miskamm [114]

Answer: Option (D) is the correct answer.

Explanation:

Atomic number of lithium is 3 and electrons in its shell are distributed as 2, 1. Atomic number of chlorine is 17 and electrons in its shell are distributed as 2, 8, 7.

Thus, we can see that lithium has 1 extra electron and chlorine has deficiency of 1 electron. Therefore, in order to gain stability lithium will transfer its 1 extra electron to chlorine atom.

Thus, we can conclude that electrons are transferred from the lithium atom to the chlorine atom.

6 0

3 years ago

Read 2 more answers

Calculate the time needed for a constant current of 0.961 a to deposit 0.500 g of co(ii) as

Vera_Pavlovna [14]

1.70 × 10³ seconds

<h3>Explanation </h3>

$\text{Co}^{2+}$ + 2 e⁻ → $\text{Co}$

It takes two moles of electrons to reduce one mole of cobalt (II) ions and deposit one mole of cobalt.

Cobalt has an atomic mass of 58.933 g/mol. 0.500 grams of Co contains $0.500 / 58.933 = 8.484\times 10^{-3} \; \text{mol}$ of Co atoms. It would take $2 \times 8.484 \times 10^{-3} = 0.01697 \; \text{mol}$ of electrons to reduce cobalt (II) ions and produce the $8.484\times 10^{-3} \; \text{mol}$ of cobalt atoms.

Refer to the Faraday's constant, each mole of electrons has a charge of around 96 485 columbs. The 0.01697 mol of electrons will have a charge of $1.637 \times 10^{3} \; \text{C}$ . A current of 0.961 A delivers 0.961 C of charge in one single second. It will take $1.637 \times 10^{3} / 0.961 = 1.70 \times 10^{3} \; \text{s}$ to transfer all these charge and deposit 0.500 g of Co.

4 0

2 years ago

What is thr driving force of convection in the atmosphere and ocean?

AleksAgata [21]

<span>Mantle convection is the slow creeping motion of Earth's rocky mantle caused by convection currents carrying heat from the interior of the earth to the surface. It is one of 3 driving forces that causes tectonic plates to move around the Earth's surface.</span>

5 0

3 years ago

Why is hydrogen placed in group one of the<br> periodic table?

Mice21 [21]

Answer:

Hydrogen has only 1 valence electron in its outermost shell.

Explanation:

6 0

3 years ago