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.
<h3>Explanation</h3>
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.
The larger the piece the longer it will take to break down. This is because it has more mass that needs to be broken down.
Answer:
Argon (Ar) is smallest element in 3rd period in periodic table.
Answer: Pt(Cl)2(NH3)2
Explanation:
In the formation of the complex, the oxidation number of platinum is plus two (+2) and two chloride ions cancel it out by their oxidation number of -1 each. Hence the complex has an overall charge of zero. It is thus neutral with no charge attached to its formula.
Answer: The enzyme has effectively becomes saturated.
Explanation:
Increasing substrate concentration increases the reaction rate this is because more substrate molecules will collide with enzymes molecules so more product will be formed, but at a point any increase in concentration will have no effect on the rate of reaction because substrate concentration will no longer be the limiting factor.
