For this reaction, C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O, the ∆H is –2200 kJ. If two moles of C3H8(g) reacted with excess oxygen, what would be true? A) 4400 kj of heat released into surroundings
B) 4400 kj of heat absorbed by system
C) 1100 kJ heat released into surroundings
D) 1100 kJ heat absorbed by system

A) 4400 kj of heat released into surroundings

Reaction

C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O, the ∆H is –2200 kJ

Reaction exothermic( ∆H=-, released heat to surrounding) and for combustion of 1 mole of C3H8

So for two moles of C3H8, the enthalpy :

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.