Hydrogen bonds are intermolecular (“between-molecule”) bonds, rather than intramolecular (“within-molecule”) bonds. They occur not only in water but in other polar molecules in which positive hydrogen atoms are attracted to negative atoms in nearby molecules. Hydrogen bonds are <em>relatively weaker</em> as chemical bonds. For example, they are much weaker than the bonds holding atoms together within molecules of covalent compounds.
Hydrogen bond is<em> weaker </em>than ionic and covalent bonds. Example: Water molecules are held to each other by intermolecular forces of attraction. Covalent bonds are the strongest bonds, meaning that atoms are actually held together by the physical sharing of electrons.
Answer:
Option D.
Explanation:
First we convert the given reactant masses into moles, using their respective molar masses:
- 4.00 g H₂ ÷ 2 g/mol = 2 mol H₂
- 6.20 g P₄ ÷ 124 g/mol = 0.05 mol P₄
0.05 moles of P₄ would react completely with (6*0.05) 0.3 moles of H₂. There are more H₂ moles than required, meaning H₂ is in excess and P₄ is the limiting reactant.
Now we<u> calculate how many PH₃ moles could be formed</u>, using the <em>number of moles of the limiting reactant</em>:
- 0.05 mol P₄ *
= 0.2 mol PH₃
Finally we <u>convert 0.2 mol PH₃ into grams</u>, using its <em>molar mass</em>:
- 0.2 mol PH₃ * 34 g/mol = 6.8 g
So the correct answer is option D.
Answer:
= 100kJ
Explanation:
The reverse reaction's activation energy of a reaction is the activation energy of the forward reaction plus ΔH of the reaction:
Ea of forward reaction =75kJ
∆H = -175 kJ/mol
Ea of reverse reaction = 75 +(-175)
= 100kJ
Note that a reverse reaction is one which can proceed in both direction depending on the conditions.
C, erosion. Erosion is the natural process of breaking down natural products through wind, or similar natural resources.
