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Gwar [14]
2 years ago
5

How are the sizes of stars measured? I just need a simple answer

Chemistry
1 answer:
S_A_V [24]2 years ago
7 0
They are determined by the length of time it takes for light to travel from the Earth to the desired star
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Nitrogen and hydrogen combine to form ammonia in the Haber process. Calculate (in kJ) the standard enthalpy change ∆H° for the r
Kazeer [188]

Answer:

∆H° rxn = - 93 kJ

Explanation:

Recall that a change in standard in enthalpy, ∆H°, can be calculated from the inventory of the energies, H, of the bonds  broken minus bonds formed (H according to Hess Law.

We need to find in an appropiate reference table the bond energies for all the species in the reactions and then compute the result.

              N₂ (g)   +            3H₂ (g)   ⇒                          2NH₃ (g)

1 N≡N = 1(945 kJ/mol)     3 H-H = 3 (432 kJ/mol)       6 N-H = 6 ( 389 kJ/mol)

∆H° rxn = ∑  H bonds broken  - ∑ H bonds formed

∆H° rxn = [ 1(945 kJ)   + 3 (432 kJ) ] - [ 6 (389 k J]

∆H° rxn = 2,241 kJ -2334 kJ = -93 kJ

be careful when reading values from the reference table since you will find listed N-N bond energy (single bond), but we have instead a triple bond,  N≡N,  we have to use this one .

8 0
3 years ago
When trying to determine whether or not an atom gives up electrons easily, do chemists look at electronegativity or ionization p
Archy [21]
Here I found some info at Yahoo answers: https://answers.yahoo.com/question/index?qid=20090119191941AAB7oAb
The more electronegative an atom is the more unwilling it is to lose its electrons in a compound. If you do try to take a very EN atom away from a compound you'll need to apply a lot of energy for that to happen. I can give an example of a single atom though 

<span>Cl has 7 valence electron filled and every atom wants to be like nobles (noble gases), so it's not going to give an electron away b/c it's really close to being like a noble gas. Noble gases are the most stable atoms, which is why I say stability counts.</span>
4 0
3 years ago
Name the 3 largest countries in the Middle East
avanturin [10]

ANSWER:

1. Egypt

2. Turkey

3. Iran

Explanation:

7 0
2 years ago
Which statements describe Newton and the law of universal gravitation? Check all that apply.
jonny [76]

Answer:

Newton believed that gravity was a force.

The law of universal gravitation offers a mathematical explanation for the attraction between the moon and Earth.

Newton was the first to have the idea that gravity is everywhere.

8 0
3 years ago
Read 2 more answers
What is the mass percent of nitrogen in:<br><br> 1. N2O<br> 2. NO<br> 3. NO2<br> 4. N2O2
Temka [501]
We’re going to use the mass percent formula shown below:



For the percent by mass N, we’re going to rewrite the equation as:

98% (271 ratings)
View Complete Written Solution
Problem Details
Calculate the mass percent composition of nitrogen in each nitrogen-containing compound:

c. NO2
5 0
2 years ago
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