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scoundrel [369]
2 years ago
12

The melting points for the second series transition elements increase from 1526˚C for yttrium to 2623˚C for molybdenum and then

decrease again to 321˚C for cadmium. Account for this trend in terms of band theory.
Chemistry
1 answer:
boyakko [2]2 years ago
6 0

Answer:

The melting points of the second series of transition elements are electrons are entering to the type of orbital.

Explanation:

Transition elements have "d" band that can overlap with the "s' band to give a composite band. The composite band have six molecular orbitals per metal atom.

Half of the molecular orbitals are the anti bonding.So, maximum bonding occurs when the molecular orbitals contains six electrons i.e. the metal has six valence electrons per each metal atom.

When the maximum bonding occurs then it shows maximum melting point.

So, molybdenum shows melting point at 2623^{o}C and after that the electrons goes into the antibonding and reaches minimum for cadmium when the anti boning orbital is completely filled. So, the melting point of the cadmium is tex]321^{o}C[/tex].

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A serving of soup contains 5.0 g of fat, 20.0 g of carbohydrates, and 3.0 g of protein. Determine how many kilocalories (kcal) a
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<u>Answer:</u> The amount of kilocalories contained in the given serving of soup is 0.137 kCal

<u>Explanation:</u>

<u>As per the USDA:</u>

Carbohydrates provide 4 calories per gram, protein provides 4 calories per gram, and fat provides 9 calories per gram.

We are given

Mass of fat in the soup serving = 5.0 g

Mass of carbohydrates in the soup serving = 20.0 g

Mass of protein in the soup serving = 3.0 g

Conversion factor used:  1 kCal = 1000 Cal

Applying unitary method:

  • <u>For Fat:</u>

1 gram of fat provides 9 calories

So, 5.0 gram of fat will provide = \frac{9}{1}\times 5.0=45Cal=0.045kCal

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1 gram of carbohydrates provides 4 calories

So, 20.0 gram of carbohydrates will provide =\frac{4}{1}\times 20.0=80Cal=0.080kCal

  • <u>For Proteins:</u>

1 gram of proteins provides 4 calories

So, 3.0 gram of fat will provide = \frac{4}{1}\times 3=12Cal=0.012kCal

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4 0
3 years ago
When the metal was placed in the calorimeter, its temperature dropped to the equilibrium temperature. Calculate the change in te
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Answer:

1st one= -79.6

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Explanation:

Good luck!

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3 years ago
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