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cupoosta [38]
3 years ago
8

The emission spectrum for an element is? Select all that apply

Chemistry
1 answer:
lesya [120]3 years ago
4 0

Answer:  You didn't give anything to select, however, the emission spectrum of a chemical element is frequencies of electromagnetic radiation emitted due to an atom or molecule making a transition from a high energy state to a lower energy state.

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1.15 g of a metallic element needs 300 cm3 of oxygen for complete reaction, at 298 K and 1 atm
sashaice [31]
1) Calculate the number of moles of O2 (g) in 300 cm^3 of gas at 298 k and 1 atm


Ideal gas equation: pV = nRT => n = pV / RT


R = 0.0821 atm*liter/K*mol

V = 300 cm^3 = 0.300 liter

T = 298 K

p = 1 atm


=> n = 1 atm * 0.300 liter / [ (0.0821 atm*liter /K*mol) * 298K] = 0.01226 mol


2) The reaction of a metal with O2(g) to form an ionic compound (with O2- ions) is of the type


X (+) + O2 (g) ---> X2O          or   


2 X(2+) + O2(g) ----> X2O2 = 2XO     or


4X(3+) + 3O2(g) ---> 2X2O3


 
In the first case, 1 mol of metal react with 1 mol of O2(g); in the second case, 2 moles of metal react with 1 mol of O2(g); in the third, 4 moles of X react with 3 moles of O2(g)



So, lets probe those 3 cases.


3) Case 1: 1 mol of metal X / 1 mol O2(g) = x moles / 0.01226 mol

=> x = 0.01226 moles of metal X


Now you can calculate the atomic mass of the hypotethical metal:

1.15 grams / 0.01226 mol = 93.8 g / mol


That does not correspond to any of the metal with valence 1+


So, now probe the case 2.



4) Case 2:


2moles X metal / 1 mol O2(g) = x / 0.01226 mol


=> x = 2 * 0.01226 = 0.02452 mol


And the atomic mass of the metal is: 1.15 g / 0.02452 mol = 46.9 g/mol


That is similar to the atomic mass of titanium which is 47.9 g / mol and whose valece is 2+.


4) Case 3


4 mol meta X / 3 mol O2 = x / 0.01226 => x = 0.01226 * 4 / 3 = 0.01635 


atomic mass = 1.15 g / 0.01635 mol = 70.33 g/mol


That does not correspond to any metal.


Conclusion: the identity of the metallic element could be titanium.
5 0
3 years ago
The small 2 next to Nitrogen is called the ____.
klasskru [66]
1. Subscript is below
2. Coefficient large 2 indicates the number of moles
3. Atoms
1/2 O2 + H2 —> H2O
It’s the atoms that balance on each side
Notes that 1/2 is the coefficient and 2 is the subscript in H2 and H2O
3 0
3 years ago
Read 2 more answers
Assessment timer and count
Aneli [31]

Answer:

I think it's the last one.

Explanation:

Because gravity is what makes our planets stay still and stops our planets from dropping and as they orbit around the sun that's what keeps the moon from bumping into earth. I hope this helps and makes sense.

<h3>p.s. can I pls be ur brainliest answer, I'd appreciate it </h3>
3 0
3 years ago
What happens to ice as it melts energy
KonstantinChe [14]

Answer:

Energy is added (postive enthalpy)

Explanation:

Ice melting means solid turns into liquid. Solid is more stable than liquid thus you must put in energy to weaken the forces of solid and turn it into liquid. Thus, you must put in energy to melt ice. This makes the enthalpy of the system to be positive.

5 0
2 years ago
Is solubility a physical change? Defend your answer.
fredd [130]

Answer:

yes

Explanation:

Solubility is an observation and no chemical reaction takes place. The composition of the compound/element is not changed.

- Hope that helped! Please let me know if you need further explanation.

3 0
3 years ago
Read 2 more answers
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