Drag each label to the correct location on the chart. Classify each reaction as endothermic or exothermic.
1 answer:
A reaction is exothermic if Δ<em>H</em> (or in some textbooks) is negative:
- H₂ + Br → 2 HBr, ΔH < 0.
- CH₄ + 2 O₂ → CO₂ + 2 H₂O, ΔH < 0.
A reaction is endothermic if Δ<em>H</em> is positive:
- 2 NH₃ → N₂ + 3 H₂, ΔH > 0.
- 2 HCl → H₂ + Cl₂ ΔH > 0.
The enthalpy of a system is the sum of its internal energy. ΔH < 0 indicates that the reactants lose internal energy in the reaction. Energy conserves, and those internal energies must have converted to some other form of energy. They typically end up as thermal energy. The reaction will release heat since it is exothermic.
Similarly, ΔH > 0 indicates that the reactants gains internal energy in the reaction. Energy conserves. As a result, the reaction must have gained energy from its surroundings. The reaction will be endothermic since it absorbs heat.
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Answer: 404.04 kJ.
Explanation:
To calculate the moles, we use the equation:
moles of
According to stoichiometry :
2 moles of on burning produces = 1036 kJ
Thus 0.78 moles of on burning produces =
Thus the enthalpy change when burning 26.7 g of hydrogen sulfide is 404.04 kJ.
Answer:
The chronic daily intake during the period of exposure is most nearly 0.012 mg/kg day.
Explanation:
Number of hours worker exposed to xylene =
The concentration of xylene in the workplace =
The worker is inhaling air at a rate of .
Amount xylene inhaled by worker in an hour :
=
Amount xylene inhaled by worker in 320 hours:
1 μg = 0.001 mg
Amount xylene inhaled by worker in 320 hours = 11.520 mg
1 day = 24 hours
Amount xylene inhaled by worker in 1 day:
Assuming 70 kg body mass, the chronic daily intake of xylene :
The chronic daily intake during the period of exposure is most nearly 0.012 mg/kg day.