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riadik2000 [5.3K]
1 year ago
5

Imagine you are given a mystery element. It is, however, a discovered and known element. You may perform a maximum of two observ

ations or tests to determine its identity. Time and money is critical, so you need to prioritize your tests. If you can identify the mystery element with a single test, you get 100 super-geek points from your research lab team.
Pick two tests and justify why you think they will identify the mystery element with certainty. If you think the first test will be enough, explain why.

Choose from these available tests:
• classification into metal, nonmetal, or metalloid
• count of valence electrons
• count of electron shells
• atomic radius (error range: +/- 1 pm)
• electronegativity (error range: +/- 0.1)
• first ionization energy (error range: +/- 10 kJ/mole)
• melting point (error range: +/- 10 C)
• boiling point (error range: +/- 20 C)

Chemistry
2 answers:
miv72 [106K]1 year ago
6 0

The classification of it being a metal, nonmetal, or metalliod will be useful in the process of elimination to determine what it is. Then for the second test, meauring the atomin radius will narrow it down quicker to the mystery elemet's name.

Since you determined what part of the periodic table it's on, then when measuring the atomic radius, you should be able to pinpoint what the element is more surely.

Nadusha1986 [10]1 year ago
3 0

Answer:

Count of Valence electron followed by electron shells

Explanation:

The periodic table has certain very unique properties that help identify the elements.

The number of valence electrons in any element can be determined by the placement of the element in the group. An element from group III will have three valence electrons.

Hence, this test will help locate the group of the element in question.

This test should be followed by the number of electron shells.

In the Periodic table, the placement of any element in the row depends on the number of electron shells. An element from row II will have two electron shell.

These two tests will work like coordinates on the Periodic Table.

For example, the result is Group II, Row 3 is Calcium.

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A scientist measures the speed of sound in a monatomic gas to be 449 m/s at 20∘C. What is the molar mass of this gas?
Ivan

Answer:

The molar mass of the gas is 36.25 g/mol.

Explanation:

  • To solve this problem, we can use the mathematical relation:

ν = \sqrt{3RT/M}

Where, ν is the speed of light in a gas <em>(ν = 449 m/s)</em>,

R is the universal gas constant <em>(R = 8.314 J/mol.K)</em>,

T is the temperature of the gas in Kelvin <em>(T = 20 °C + 273 = 293 K)</em>,

M is the molar mass of the gas in <em>(Kg/mol)</em>.

ν = \sqrt{3RT/M}

(449 m/s) = √ (3(8.314 J/mol.K) (293 K) / M,

<em>by squaring the two sides:</em>

(449 m/s)² = (3 (8.314 J/mol.K) (293 K)) / M,

∴ M = (3 (8.314 J/mol.K) (293 K) / (449 m/s)² = 7308.006 / 201601 = 0.03625 Kg/mol.

<em>∴ The molar mass of the gas is 36.25 g/mol.</em>


7 0
2 years ago
Methyl salicylate, C8H8O3, the odorous constituent of oil of wintergreen, has a vapour pressure of 1.00 torr at 54.3oC and 10.0
abruzzese [7]
<span>Use the Arrhenius equation. Use p1 and p2 and T1 and T2 and solve for Ea (actgivation energy) in Joules, then plug that back into the Arrhenius equation and either p1 or p2 to calculate p at 25C.</span>
5 0
1 year ago
A sodium ion, Na+, with a charge of 1.6×10−19C and a chloride ion, Cl− , with charge of −1.6×10−19C, are separated by a distance
sasho [114]

Answer:

W\geq 2.1x10^{-19}J

Explanation:

Due to Coulomb´s law electric force can be described by the formula F=K\frac{q_{1}.q_{2}}{r^{2}}, where K is the Coulomb´s constant (9x10^{9} N\frac{m^{2} }{C^{2} }), q_{1}= Charge 1 (Na+ in this case), q_{2} is the charge 2 (Cl-) and r is the distance between both charges.

Work made by a force is W=F.d and total work produced is the change in energy between final and initial state. this is W=W_{f} -W_{i}.

so we have W=W_{f} -W_{i} =(K\frac{q_{(Na+)}q_{(Cl-)}rf}{r_{f} ^{2}})-(K\frac{q_{(Na+)}q_{(Cl-)}ri}{r_{i} ^{2}})=Kq_{(Na+)}q_{(Cl-)[\frac{1}{{r_{f}}} -\frac{1}{{r_{i}}}]

Given that ri= 1.1nm= 1.1x10^{-9}m and rf= infinite distance

W=(9x10^{9})(1.6x10^{-19})(-1.6x10^{-19})[\frac{1}{\alpha }-\frac{1}{(1.1x10^{-9})}]=2.1x10^{-19}J

6 0
2 years ago
A 0.15 m solution of chloroacetic acid has a ph of 1.86. What is the value of ka for this acid?
dem82 [27]

Answer: 1.67\times 10^{-3}

Explanation:

ClCH_2COOH\rightarrow ClCH_2COO^-+H^+

   cM              0             0

c-c\alpha        c\alpha          c\alpha  

So dissociation constant will be:

K_a=\frac{(c\alpha)^{2}}{c-c\alpha}

Given:  c = 0.15 M

pH = 1.86

K_a = ?

Putting in the values we get:

Also pH=-log[H^+]

1.86=-log[H^+]

[H^+]=0.01

[H^+]=c\times \alpha

0.01=0.15\times \alpha

\alpha=0.06

As [H^+]=[ClCH_2COO^-]=0.01

K_a=\frac{(0.01)^2}{(0.15-0.15\times 0.06)}

K_a=1.67\times 10^{-3]

Thus the vale of K_a for the acid is 1.67\times 10^{-3}

4 0
2 years ago
When metals combine with nonmetals, the metallic atoms tend to 1. lose electrons and become positive ions 2. lose electrons and
Vika [28.1K]
The correct answer is 1. Lose electrons and become positive ions.


I hope my answer was beneficial to you! c:
5 0
1 year ago
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