Answer: A. Liquefy hydrogen under pressure and store it much as we do with liquefied natural gas today.
Explanation:
Current Hydrogen storage methods fall into one of two technologies;
- <em>physical storage</em> where compressed hydrogen gas is stored under pressure or as a liquid; and
- <em>chemical storage</em>, where the hydrogen is bonded with another material to form a hydride and released through a chemical reaction.
Physical storage solutions are commonly used technologies but are problematic when looking at using hydrogen to fuel vehicles. Compressed hydrogen gas needs to be stored under high pressure and requires large and heavy tanks. Also, liquid hydrogen boils at -253°C (-423°F) so it needs to be stored cryogenically with heavy insulation and actually contains less hydrogen compared with the same volume of gasoline.
Chemical storage methods allow hydrogen to be stored at much lower pressures and offer high storage performance due to the strong binding of hydrogen and the high storage densities. They also occupy relatively smaller spaces than either compressed hydrogen gas or liquified hydrogen. A large number of chemical storage systems are under investigation, which involve hydrolysis reactions, hydrogenation/dehydrogenation reactions, ammonia borane and other boron hydrides, ammonia, and alane etc.
Other practical storage methods being researched that focuses on storing hydrogen as a lightweight, compact energy carrier for mobile applications include;
- Nanostructured metal hydrides
- Liquid organic hydrogen carriers (LOHC)
A negative formation enthalpy means that the reaction is exothermic, or that heat is released during the process.
(C,)
Answer:
145 hours
Explanation:
Since one hour of riding a bicycle takes up 505 kcal of energy. It is also stated that one gram of body fat is equal to 7.70 kcal. Also, it is given that 1 pound of body fat is equal to 454 g.
Hence;
1 Ib= 454 g
21 Ib= 21 × 454/1 = 9534 g
But
1g of body fat = 7.70kcal
9534 g of body fat = 9534 × 7.70 kcal/1 = 73411.8 kcal
If 505 kcal is lost in 1 hour
73411.8 kcal is lost in 73411.8 kcal × 1hour/505k cal = 145 hours
Missing question:
<span>A. [PdZn(H2O)2(CO)2]Br4.
B. [Zn(H2O)2(CO)2]2[PdBr4].
C. [Pd(H2O)2][Zn(CO)2]Br4.
D. [Pd(H2O)2]2[Zn(CO)2]3Br4.
E. [Zn(H2O)2(CO)2][PdBr4].
</span>Answer is: E. [Zn(H2O)2(CO)2][PdBr4]..
In this complex diaqua means two waters (H₂O), <span>dicarbonyl means two carbonyl groups (CO), zinc(Zn) and palladium (Pd) are central atoms or metals, bromine has negative charge -1. Bromine, water and carbonyl are ligands.</span>
Answer:
d) All have identical pressures
Explanation:
The kinetic molecular theory explains how gas molecules behave in a container. By this theory, the gas particles behave like hard, spherical objects in a state of constant, random motion; these particles collide between them and at the walls of the container. Besides, the kinetic energy of the gas depends only on the temperature.
The pressure is the force that the particles are applying under some area, so by the theory, it depends on the number of moles (amount of particles that collides and make the force), the volume of the container and the kinetic energy, or the temperature.
Because all gases have the same number of moles and are at the same temperature and the same volume, they'll have the same pressure.
