Answer:
When an atom attracts extra electrons it becomes a negative ion. The negative ion is larger than the original atom. The positive nucleus remains the same, with the same attractive force. However, this attractive force is now pulling on more electrons and therefore has less effect.
Or
Positive ions are formed by removing one or more electrons from the outermost region of the atom. The opposite is true of negative ions. When electrons are added to form an anion, the increased electron-electron repulsions cause the electrons to spread out more in space. Thus, anions are larger than their parent atoms.
Convert 72g of water into moles of water using molecular weights.
So water is H2O so add up those molecular weights (H=1 and O=16)
2(1)+(16) = 18 g/mol
Then convert so 72g / (18 g/mol) = 4 mol
Now you can convert mol of water to mol of oxygen. So 4 mol of water is 4 mol of oxygen. Then use oxygen molecular weight to find grams again.
4 mol oxygen * 16 g/mol = 64g of oxygen
If we were doing hydrogen instead of oxygen there would be 8 mol hydrogen in 4 mol of water (2 H’s in every H2O molecule) and since we have 74 grams and oxygen is 64 grams, Hydrogen should be 8 grams. Math to check below
8 mol hydrogen * 1 g/mol = 8g of hydrogen
It all adds to 72 so we are correct.
There is an error in the first sentence of the question; the right format is:
Suppose a 500.mL flask is filled with 1.9mol of NO3 and 1.6mol of NO2.
It should be NO2 and not NO.
Answer:
The equilibrium molarity of NO = 0.21695 m
Explanation:
Given that :
the volume = 500 mL = 0.500 m
number of moles of 
number of moles of 
Then we can calculate for their respectively concentrations as :
![[NO_3] = \frac{number \ of \ moles}{volume}](https://tex.z-dn.net/?f=%5BNO_3%5D%20%3D%20%5Cfrac%7Bnumber%20%5C%20of%20%5C%20moles%7D%7Bvolume%7D)
![[NO_3] = \frac{1.9}{0.500}](https://tex.z-dn.net/?f=%5BNO_3%5D%20%3D%20%5Cfrac%7B1.9%7D%7B0.500%7D)
![[NO_3] = 3.8 \ M](https://tex.z-dn.net/?f=%5BNO_3%5D%20%3D%203.8%20%5C%20M)
![[NO_2] = \frac{number \ of \ moles}{volume}](https://tex.z-dn.net/?f=%5BNO_2%5D%20%3D%20%5Cfrac%7Bnumber%20%5C%20of%20%5C%20moles%7D%7Bvolume%7D)
![[NO_2] = \frac{}{} \frac{1.6}{0.500}](https://tex.z-dn.net/?f=%5BNO_2%5D%20%3D%20%5Cfrac%7B%7D%7B%7D%20%5Cfrac%7B1.6%7D%7B0.500%7D)
![[NO_2] = 3.2 \ M](https://tex.z-dn.net/?f=%5BNO_2%5D%20%3D%203.2%20%5C%20M)
The chemical reaction can be written as:

The ICE table is as follows;

Initial 3.8 - 3.2
Change +x x -2x
Equilibrium 3.8+x +x 3.2 - 2x
![K_c=\frac{[NO_2]^2}{[NO_3][NO]}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BNO_2%5D%5E2%7D%7B%5BNO_3%5D%5BNO%5D%7D)



Using quadratic formula;

= 
= 0.21695 OR -3.7283
Going by the positive value;
x = 0.21695
![[NO_3] = 3.8 +x = 3.8 + 0.21695](https://tex.z-dn.net/?f=%5BNO_3%5D%20%3D%203.8%20%2Bx%20%20%3D%203.8%20%2B%200.21695)
= 4.01695 m
[NO] = x = 0.21695 m
![[NO_2] = 3.2 +x = 3.2 + 0.21695](https://tex.z-dn.net/?f=%5BNO_2%5D%20%3D%203.2%20%2Bx%20%20%3D%203.2%20%2B%200.21695)
= 3.41695 m
Answer:
980,536.2 grams
Explanation:
The mass of a compound is equal to its moles times its molar mass.
The molar mass of PCl3 is 137.33 g/mol
137.33 x 7.14 x 10^3 = 980,536.2