First determine the formal oxidation numbers:
N changes from +2 to +5 going from NO to (NO3)- O remains -2 the whole time Cr changes from +6 to +3
Now write the half reactions, balance the oxygens with the required number of waters and then balance the hydrogens with the required number of protons:
Oxidation half reaction:
NO(aq) + 2 H2O(l) ---> (NO3)-(aq) + 4 H+(aq) + 3 e-
Reduction half reaction:
(Cr2O7)2-(aq) + 14 H+(aq) + 6 e- ---> 2 Cr3+(aq) + 7 H2O(l)
Now balance the number of electrons on both sides and add them together:
2 NO(aq) + 4 H2O(l) ---> 2 (NO3)-(aq) + 8 H+(aq) + 6 e- (Cr2O7)2-(aq) + 14 H+(aq) + 6 e- ---> 2 Cr3+(aq) + 7 H2O(l) --------------------------------------... 2 NO(aq) + (Cr2O7)2-(aq) + 6 H+(aq) ---> 2 (NO3)-(aq) + 2 Cr3+(aq) + 3 H2O(l)
Notice that the charge is the same in both sides, which is an indication that the redox equation has been balanced correctly:
-2 + 6 = -2 + 2(+3) +4 = +4
To find how many atoms are in the compound, we first have to find how many moles there are. The numbers in the subscript tell you how many moles of each element are present in the compound. Therefore, to find the number of total moles, we can add up each of the numbers in the subscript:
Cu₂Mg₁H₁O₁ *when there is no number under an element, it is implied that there is 1 mole of the element
2+1+1+1=5 moles
We can then use Avogadro's number and dimensional analysis to find how many atoms are in the compound (Avogadro's number is 6.02x10^23):
5 moles (6.02x10^23/1 mole)= 3.01x10^24 atoms
C, because Boiling doesnt change the substance, making it a Physical property
It's -Bohr's Model- becuase Dalton I dont think did a model. Thomson's was the "Plum Pudding Model." Ernest Rutherford drew one out(I dont know i dont have a model down though) so it the only one left is Dalton's Model which is it. (Hopefuly)