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Romashka-Z-Leto [24]
3 years ago
8

Which choice contains a FALSE statment? A. For the vaporization of liquid benzene ΔH is positive. B. For the formation of 1 mol

nitrogen dioxide from its elements (heat is absorbed)ΔH is negative. C. For the sublimation of dry ice [conversion of CO₂(s) directly to CO₂(g)] ΔH is positive. D. For the reaction of 1 mol of sulfur dioxide with oxygen ΔH is negative. E. None of these is/are FALSE
Chemistry
1 answer:
ser-zykov [4K]3 years ago
7 0

Answer:

B is False

Explanation:

In physical chemistry we always look from system's perspective, so if we heat something ΔH is positive and if the system gives heat out then ΔH is negative.

A. We have to give energy to benzene to evaporate it. Statement true.

B. If heat is absorbed then the enthalpy must be positive.

C. The heat is absorbed then ΔH is positive.

D. Usually for burning heat is exposed from system. So enthalpy is negative.

E. Obvious

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A ____________ star would have the hottest surface temperature.
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Answer:

Blue

Explanation:

If you look at a flame, blue is always at the bottom right? So that would be common sense that blue would be the hottest.

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3 years ago
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What is the salt formers group number is?
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The halogens are five non-metallic elements found in group 17 of the periodic table. The term "halogen" means "salt-former" and compounds containing halogens are called "salts". All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1.

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2 years ago
To balance the reaction what coefficients (numbers) are needed: HBr +KOH ---> KBr + H2O
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Answer:

H2Br + 2KOH ----- K2Br + 2H2O

5 0
3 years ago
Is there a qualitative difference between the enthalpy of a phase transition versus the enthalpy of a heating or cooling process
Vesna [10]

Answer:

No

Explanation:

given that, enthalpy is a state function, that means it depends only on the initial and final states,  there is no difference between the enthalpy of a phase transition versus the enthalpy of a heating or cooling process, when the cooling or heating process finish in a change of phase.

It does not  matter which way we take to cool or heat the substances the Enthalpy of this process will be the same.

3 0
3 years ago
After he conducted cathode ray tube experiments proving the existence of negatively charged particles we now call electrons, Tho
Lina20 [59]

Answer:

Answer is explained below;

Explanation:

In 1904, after the discovery of the electron, the English physicist Sir J.J. Thomson proposed the plum pudding model of an atom. In this model, the atom had a positively-charged space with negatively charged electrons embedded inside it i.e., like a pudding (positively charged space) with plums (electrons) inside.

In 1911, another physicist Ernest Rutherford proposed another model known as the Rutherford model or planetary model of the atom that describes the structure of atoms. In this model, the small and dense atom has a positively charged core called the nucleus. Also, he proposed that just like the planets revolving around the Sun, the negatively charged electrons are moving around the nucleus.

By conducting a gold foil experiment, Rutherford disproved Thomson's model. In this experiment, positively charged alpha particles emitted from a radioactive source enclosed within a protective lead were used which was then focused into a narrow beam. It was then passed through a slit in front of which a thin section of gold foil was placed. A fluorescent screen (coated with zinc sulfide) was also placed in front of the slit to detect alpha particles which on striking the fluorescent screen would produce scintillation (a burst of light) which was visible through a microscope attached to the back of the screen.

He observed that most of the alpha particles passed straight through the gold foil without any resistance and this implied that atoms contain a large amount of open space. The slight deflection of some of the alpha particles, the large-angle scattering of other alpha particles and even the bouncing back of a very few alpha particles toward the source suggested their interactions with other positively charged particles inside the atom.

So, he concluded that only a dense and positively charged particle such as the nucleus would be responsible for such strong repulsion. Also, the negatively charged electrons electrically balanced the positive nuclear charge and they moved around the nucleus in circular orbits. Between the electrons and nucleus, there was an electrostatic force of attraction just like the gravitational force of attraction between the sun and the revolving planets.

Later, the Rutherford model was replaced by the Bohr atomic model.

6 0
3 years ago
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