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Mama L [17]
3 years ago
15

Platinum crystallizes in a face-centered cubic cell. the density of platinum is 21.4 g/cm3. calculate the radius of the platinum

atom in pm
Chemistry
1 answer:
IgorLugansk [536]3 years ago
7 0
1 mole of platinum has a mass of 195 g therefore 1 atom will have a mass of 195 g /(6.02 ×10^23) = 3.239 × 10^-22 g
Density is given by dividing mass by volume, thus to get volume, mass is divided by density. 
The volume = (3.239 × 10^-22)/21.4 
                    = 1.514 × 10^-23 cm³
But volume of a sphere is given by 4/3πr³
Therefore, r³ = 3.6129 × 10^-24 
                 r   = ∛(3.6129 × 10^-24)
                      = 1.534 × 10^ -8 cm
Therefore, the radius of the platinum atom is 1.534 × 10^-8 cm

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Calculate the energy difference for a transition in the paschen series for a transition from the higher energy shell n=4. expres
Troyanec [42]
Electrons are orbiting around the nucleus in a specific energy level as described in Bohr's atomic model. There are 7 energy levels all in all; 1 being the strongest and nearest to the nucleus, and 7 being the weakest and farthest away from the nucleus. Electron can transfer from one energy level to another. If it increases energy, it absorbs energy. If it goes down an energy level, it emits energy in the form of light. This light can be measure in wavelength through the Rydberg equation:

1/λ =R(1/n₁² -1/n₂²), where
λ is the wavelength
R is the Rydberg constant equal to 1.097 × 10⁻7<span> per meter
n</span>₁ and n₂ are the energy levels such that n₂>n₁

In the Paschen series is an emission spectrum of hydrogen when the energy level is at least n=4. So, this covers n=4 to n=7.

1/λ =(1.097 × 10⁻7)(1/4² -1/7²)
λ  = 216.57 ×10⁻⁶ m or 216.57 μm
5 0
3 years ago
How do you convert a temp from celsusis to kelvin
Daniel [21]
?° C + 273° K = ?° K
6 0
3 years ago
How does a refrigerator cool food and drinks
jolli1 [7]

Answer:

The evaporator is located inside a refrigerator and is the part that makes the items in the refrigerator cold. As the refrigerant turns from a liquid into a gas through evaporation, it cools the area around it, producing the proper environment for storing food.

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3 years ago
Determine the entropy change for the combustion of gaseous propane, C3H8, under standard state conditions to give gaseous carbon
mina [271]

Answer:

ΔS°reaction = 100.9 J K⁻¹ (mol C₃H₈)⁻¹

Explanation:

The equation for the reaction is given as;

C₃H₈(g) + 5O₂(g) → 4H₂O(g) + 3CO₂(g)

In order to determine the entropy change, we have to use the entropy valuues for the species in the reaction. This is given as;

S°[C₃H₈(g)] = 269.9 J K⁻¹ mol⁻¹

S°[O₂(g)] = 205.1 J K⁻¹ mol⁻¹

S°[H₂O(g)] = 188.8 J K⁻¹ mol⁻¹

S°[CO₂(g)] = 213.7 J K⁻¹ mol⁻¹

The unit of entropy is J K⁻¹ mol⁻¹

Entropy change for the reaction is given as;

ΔS°reaction = ΔS°product - ΔS°reactant

ΔS°reaction = [(4 * 188.8) + (3 * 213.7)] - [269.9 + (5 * 205.1)]

ΔS°reaction = 100.9 J K⁻¹ (mol C₃H₈)⁻¹

3 0
3 years ago
How did early chemists determine which substances were elements?
padilas [110]

。☆✼★ ━━━━━━━━━━━━━━  ☾  

The correct answer would be option D

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Stay Brainly! ヅ    

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。☆✼★ ━━━━━━━━━━━━━━  ☾

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3 years ago
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