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riadik2000 [5.3K]
2 years 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]2 years 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]2 years 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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The percent yield of H_2CO_3  is, 24.44 %

Explanation:

5 0
2 years ago
The activation energy for the reaction NO2(g)+CO(g)⟶NO(g)+CO2(g) is Ea = 375 kJ/mol and the change in enthalpy for the reaction
HACTEHA [7]
Answer: 625 kj/mol

Explanation:

As shown below this expression gives the activation energy of the reverse reaction:

EA reverse reaction = EA forward reaction + | enthalpy change |

1) The activation energy, EA is the difference between the potential energies of the reactants and the transition state:

EA = energy of the transition state - energy of the reactants.

2) The activation energy of the forward reaction given is:

EA = energy of the transition state - energy of  [ NO2(g) + CO(g) ] = 75 kj/mol

3) The negative enthalpy change - 250 kj / mol for the forward reaction means that the products are below in the potential energy diagram, and that the potential energy of the products, [NO(g) + CO2(g) ] is equal to 375 kj / mol - 250 kj / mol = 125 kj/mol

4) For the reverse reaction the reactants are [NO(g) + CO2(g)], and the transition state is the same than that for the forward reaction.

5) The difference of energy between the transition state and the potential energy of [NO(g) + CO2(g) ] will be the absolute value of the change of enthalpy plus the activation energy for the forward reaction:

EA reverse reaction = EA forward reaction + | enthalpy change |

EA reverse reaction = 375 kj / mol + |-250 kj/mol | = 375 kj/mol + 250 kj/mol = 625 kj/mol.

And that is the answer, 625 kj/mol
4 0
2 years ago
Balance the following reaction. A coefficient of "1" is understood. Choose option "blank" for the correct answer if the coeffici
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2 years ago
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pychu [463]

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Unlike butter, lard contains more saturated fats, higher monounsaturated fats, and no trans fat (a type of unsaturated fat).

Thus, the presence of more saturated fats allows for more hydrogen atoms to confer heat stability to lard.

So, lard contains more hydrogen atoms

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Answer:2

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This means that barium sulphate contains two more oxygen atoms than barium hydroxide in its formula. This is clearly seen from the two formulae shown above.

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