Electrons determine the chemical properties. Protons and neutrons are in the nucleus the number of protons determines the number of electrons of an atom
Answer: There are 
molecules present in 183.2 grams of 
gas.
Explanation:
Given: Mass = 183.2 g
Number of moles is the mass of substance divided by its molar mass.
As molar mass of water is 18 g/mol. Therefore, moles of are calculated as follows.
According to the mole concept, there are 
molecules present in one mole of a substance.
Hence, molecules present in 10.17 moles are calculated as follows.
Thus, we can conclude that there are molecules present in 183.2 grams of gas.
They have the same number of electrons in their outer shells. Elements in the same group often share similar chemical properties because the outer electrons generally determine a lot of their properties
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 .
