Suppose a scientist made a claim that all spontaneous reactions are exothermic. Whic of the following would provide the strongest challenge to their claim? Suppose a scientist made a claim that all spontaneous reactions are exothermic. Which of the following would provide the strongest challenge to their claim? a. An exothermic reaction which is not spontaneous
b. An endothermic reaction that only proceeds when coupled to an exothermic reaction
c. An endothermic reaction that only proceeds when a catalytst is present
d. An endothermic reaction which is not spontaneous
e. All of the above
Answers
Answer: Option (c) is the correct answer.
Explanation:
It is given that the scientist is claiming that all the spontaneous reactions are exothermic in nature.
And, it is known that when a reaction is spontaneous in nature then is negative.
Now, the relation between Gibb's free energy, enthalpy and entropy is as follows.
=
So, when a catalyst is present in a chemical reaction then we do not need to give large amount of heat from outside. And, because of this the enthalpy of reaction will not be highly positive.
Hence, the value of will result in a negative value which means the reaction is spontaneous.
Thus, we can conclude that an endothermic reaction that only proceeds when a catalytst is present, would provide the strongest challenge to their claim.
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Answers
Final answer:
A pharmaceutical percolator is a device used to extract active compounds from plants or herbs. It works by passing a solvent through the material to dissolve the desired components. The process involves maceration, percolation, and filtration.
Explanation:
A pharmaceutical percolator is a device used in the pharmaceutical industry to extract active compounds from plants or herbs. It works on the principle of percolation, which involves passing a solvent through a solid material to dissolve the desired components. The percolation process involves three main steps:
- Maceration: The plant material is crushed or ground and mixed with a suitable solvent, such as ethanol or water. This mixture is then allowed to stand for a specific period, usually several hours or days, to allow the solvent to dissolve the active compounds.
- Percolation: The macerated mixture is then transferred to the percolator, which is a vessel with a perforated plate or bottom. The solvent is poured onto the mixture, and gravity pulls it down through the solid material, dissolving the active compounds along the way.
- Filtration: The liquid containing the dissolved active compounds, known as the percolate, is collected at the bottom of the percolator and filtered to remove any solid particles or impurities. The resulting solution can then be further processed or used directly in the production of pharmaceutical products.
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step.
B. The enthalpy is determined from the enthalpy of similar reactions.
C. The enthalpy from the final equation in a series of reactions is
used
D. Intermediate equations with known enthalpies are added together.
Answers
Hess's law is used to measure the enthalpy of a desired chemical reaction because: D. Intermediate equations with known enthalpies are added together.
What is Hess's Law?
Hess's Law is also known as Hess's law of constant heat summation (enthalpy) and it was named after a Swiss-born Russian chemist called Germain Hess.
Hess's Law states that the energy change (enthalpy) experienced in a desired chemical reaction is equal to the sum of the energy changes (enthalpies) in each chemical reactions that it is made up of or contains.
Read more on Hess's Law here: brainly.com/question/9328637
Answers
The observation in this instance relates to the quantity of heat needed to melt ice, and it is expressed in terms of weights (2 lbs and 1 lb) and a comparison (twice the amount).
Without going into detail into the different molecules or their interactions, it concentrates on the general behaviour and characteristics of the substance (ice) as a whole.
A microscopic description, on the other hand, would describe the behaviour in terms of the molecular or atomic interactions that take place at the particle level. It would go into ideas such as the amount of heat required to dissolve the intermolecular interactions between water molecules.
Therefore, the observation regarding how much heat is needed to melt ice is a macroscopic description since it ignores the underlying molecular interactions in favour of the substance's general behaviour and qualities.
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The observation that melting 2 lbs of ice requires twice the heat of melting 1 lb is a macroscopic description, focusing on observable properties and behavior without exploring microscopic details.
This observation is a macroscopic description of chemical behavior. Macroscopic descriptions involve the properties and behavior of substances on a large scale that can be observed directly, without delving into the molecular or atomic details. In this case, the statement refers to the amount of heat required to melt a certain quantity of ice, and it is expressed in terms of macroscopic, measurable quantities (pounds of ice and the associated heat).
The macroscopic observation does not provide insight into the molecular or atomic interactions within the ice but rather focuses on the overall behavior of the substance. The concept that the amount of heat required to melt 2 lbs of ice is twice that needed for 1 lb of ice is a statement about the material's behavior at a larger scale.
This observation aligns with the macroscopic principles of heat and phase transitions, where the heat required for a phase change is directly proportional to the mass of the substance undergoing the transition. The macroscopic perspective is concerned with observable properties and measurements, making it a practical and accessible way to describe chemical behavior without delving into microscopic details.
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B. has little solvent
C. it has a lot of solvent
D. has maximum solute
Answers
To dilute a solution means to add more solvent without the addition of more solute
Answers
Answer:
4.88 Cals per degree celsius
Explanation:
We have taken heat of fusion of ice = 80 cals / g
We have taken speciic heat of water = 1 cal/g per degree celsius
In this experiment , let the heat capacity of calorimeter be X.
Heat gained by ice
heat gained in melting + heat gained in getting warmed
= mass x latent heat + mass x specific heat x rise in temperature
= 17.69 x 80 + 17.69 x 1 x ( 12.9 - 0 )
= 1643.4 Cals
Heat lost by water
= mass x specific heat x fall in temperature
98.67 x 1 x ( 28.77 - 12.9 )
= 1565.89 Cals
Heat lost by calorimeter
heat capacity x fall in temperature
X x ( 28.77 - 12.9 )
Heat gained = heat lost
1643.4 = 1565.89 +15.87X
X = 4.88 Cals per degree celsius
Answers
Answer:
7.97 mol Ar
Explanation:
Use Avogadro's number to convert atoms to moles. This number is the number of atoms in one mole. There are 6.022 × 10²³ atoms in one mole.
Divide the number of atoms given by Avogadro's number.
(4.80 × 10²⁴)/(6.022 × 10²³) = 7.97 mol
There are 7.97 moles of argon.
Answer:
3.0 moles (A P E X)
Explanation: