Answer:
C) Iron Combines readily with oxygen
Explanation:
When Iron combines readily with oxygen well... it rusts making it a new substance
Mass and number of atoms always stay the same
A physical change is when the physical properties of an object change, whereas a chemical change is when the chemical properties of an object change. Iron rusting is a result of a chemical change, because the rust was not there before. Silver tarnishing is a chemical change for the same reason. Gasoline burning is also a chemical change, because gasoline changes chemically. Therefore, metal denting is a physical change, because the shape and position of an object is a physical property, and there are no new substances being formed, which are all indications of a physical change.
Answer:
55.5g of N₂
Explanation:
It is possible to find ΔH of a reaction by the sum of half-reaction (Hess's law), thus:
<em>(1) </em>4 NH₃ + 3 O₂ → 2 N₂ + 6 H₂O ΔH= -1556KJ
<em>(2) </em>N₂O + H₂ → N₂ + H₂O ΔH= -389.4 KJ
<em>(3) </em>H₂+ ½ O₂ → H₂O ΔH= -223.9 KJ
(4) = 1/2 (1) + 3 (2):
<em>(4) </em>2 NH₃ + 3 N₂O +3 H₂ + ³/₂ O₂ → 4 N₂ + 6 H₂O
ΔH = 1/2 (-1556kJ) + 3 (-389.4kJ) = -1946.2kJ
(4) - 3(3):
2 NH₃ + 3 N₂O → 4 N₂ + 3 H₂O ΔH = -1946.2kJ - 3 (-223.9 KJ)
ΔH = -1274.5 kJ
As when 5 moles of nitrogen are produced there are released 1274.5kJ, when are released 505kJ:
505kJ × (5 moles N₂ / 1274.5kJ) =<em> 1.98 moles of N₂. </em>In mass:
1.98moles N₂ ₓ (28g / 1mol) = <em>55.5g of N₂</em>