A. Decomposing water requires a high activation energy.
Explanation:
In decomposing water to release hydrogen gas to make fuel cells, the process requires a very high activation energy.
2H₂O ⇆ 2H₂ + O₂
This is the overall reaction. O-H must be broken to release free hydrogen to produce hydrogen gas.
The O-H bond is a very strong force of attraction that requires a high activation energy to overcome.
- The activation energy is the energy barrier that must be overcome before a reaction takes place.
- The sun is a renewable source of energy.
- Water decomposition produces useful oxygen gas needed by all life for cellular respiration.
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Answer:
Product: ethyl L-valinate
Explanation:
If we want to understand what it is the molecule produced we have to an<u>alyze the reagents</u>. We have valine an <u>amino acid</u>, in this kind of compounds we have an <em>amine group</em> (
) and a <em>carboxylic acid</em> group (
). Additionally, we have an <u>alcohol </u>(
) in the presence of HCl (a <u>strong acid</u>) in the first step, and a base (
).
When we have an acid and an alcohol in a vessel we will have an <u>esterification reaction</u>. In other words, an ester is produced. As the <em>first step,</em> the oxygen in the C=O (in the carboxylic acid group) would be protonated. In the <em>second step</em>, the ethanol attacks the carbon in the C=O of the carboxylic acid group producing a new bond between the oxygen in the ethanol and the carbon in the carboxylic acid. In <em>step 3</em>, a proton is transferred to produce a better leaving group (
). In <em>step 4</em>, a water molecule leaves the main structure to produce again the double bond C=O. <em>Finally</em>, a base (
) removes the hydrogen from the C=O bond to produce ethyl L-valinate
See figure 1
I hope it helps!
<u>Respuesta:</u>
16 gramos de vitamina C y 8 gramos de colorantes.
Explanation:
Debemos multiplicar el porcentaje de cada componente por la cantidad total (100 %) de zumo.
800 g de zumo = 100%
- Tenemos un 2 porciento (2 en 100 o 2/100) de vitamina C. Por lo tanto, la cantidad en gramos de vitamina C es:
2/100 x 800 g = 16 g
- Tenemos un 1 porciento de colorantes en el zumo (1/100). Por lo tanto, la cantidad en gramos de colorantes es:
1/100 x 800 g = 8 g