18. <span>Answer is </span>
A<span>
<span>Since the enthalpy of reaction is positive, the
forward reaction is<span> an endothermic reaction which means the energy
is gained from the surrounding to happen the reaction. If the temperature
decreases, according to the </span></span>Le Chatelier's principle, the system tries to become equilibrium
by increasing temperature. Since forward reaction is endothermic (because of
the bond breaking), the backward reaction is exothermic (because of the bond
making) which releases the energy to the surroundings. This makes the increase
of temperature. So if the backward reaction is promoted because of the decrease
of temperature, then the concentration of H</span><span>₂ will decrease.</span>
<span>
</span>
19. Answer is A.
The reactant side
has 2 moles/molecules of reactants and the product side has 4 moles/molecules
of products which come from 1 N₂(g) and 3 H₂<span>(g). If the pressure is reduced in the system, according to the Le Chatelier's principle, the
system tries to increase the pressure. </span><span>Hence, forward
reaction is promoted because of the higher number
of molecules in product side. If the forward reaction is promoted, the
concentration of NH</span>₃(g) will decreased.
<span>20. </span>Answer is C.
If the concentration
of reactant is increased in the
system, according to the Le Chatelier's principle, the system tries
to reduce the concentration of that reactant. So if NH₃(g) concentration
is increased, then to be equilibrium, the forward reaction will be promoted.
Then the concentration of N₂<span>(g) will increase.</span>
<span> </span>
Answer:
False
Explanation:
Increase in polarity of a molecule leads to higher boiling points. The more polar a molecule is, the higher the energy required to breaks intermolecular forces of attraction hence the higher the boiling point. This is the reason why ionic compounds and compounds having polar covalent bonds in them tend to have high boiling points.
Your answer is sublimation.
Explanation:
Combustion of a compound is the reaction with oxygen , hence , the process of combustion is an oxidation reaction.
The carbohydrates contain more amount of oxygen as compared to the fats ,
Hence ,
carbohydrates , have a lot of oxygen contents , are are already partially oxidized , but fats have lower oxygen content .
Therefore ,
The partially oxidized carbohydrates are very difficult to oxidized in comparison to fats .
Which statement describes how the binary ionic compound KBr is named? The metal is named first, and the name is unchanged. Which of these is a property of a substance that is composed of atoms that are held together by ionic bonds?
