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grandymaker [24]
2 years ago
8

Identify each process as endothermic or exothermic and indicate the sign of H . (a) an ice cube melting (b) nail polish remover

quickly evaporating after it is accidentally spilled on the skin (c) gasoline burning within the cylinder of an automobile engine
Chemistry
1 answer:
Delicious77 [7]2 years ago
7 0

Answer:an ice cube melting ∆H=+ve

nail polish remover quickly evaporating after it is accidentally spilled on the skin ∆H=-ve

gasoline burning within the cylinder of an automobile engine ∆H=-ve

Explanation:

In an endothermic process, such as the melting of an ice cube, heat is absorbed from the surrounding. The enthalpy change is positive. The evaporation a nail polish and burning of gasoline are exothermic processes which lead to the release of heat to the surrounding. The sign of the enthalpy change in both cases is negative.

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In the reaction 4Al+3O2→_Al2O3 , what coefficient should be placed in front of the Al2 to balance the reaction?
nika2105 [10]

Sorry I came a lil late,

The answer to your question is, 2.

Hope this helps! :)

6 0
3 years ago
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In the article, Invasion of the Periodical Cicadas, why do scienctists believe that cicadas only reproduce every 13 or 17 years?
frez [133]

Hi, you've asked an incomplete question. However, I assumed you are referring to the article found on the Scientific American website.

Explanation:

<em>Remember,</em> according to that article we are told that scientists notice that these insects have a long nymphal (immature form before becoming adults) stage, one that can last up to 13 to 17 years on the ground before they leave the ground looking for mating partners.

Because it is only after mating occurs at this point that their eggs are laid, that is why scientists believe that cicadas only reproduce every 13 or 17 years.

8 0
2 years ago
How many moles (of molecules or formula units) are in each sample?
Alexus [3.1K]

The number of moles in each sample will be 0.391 moles, 30.7 moles, 0.456 moles, and 1350 moles

<h3>What is the number of moles?</h3>

The number of moles of a substance is the ratio of the mass of the substance to the molar mass.

In other words; mole = mass/molar mass.

Thus:

  • moles of 18.0 g NO_2 = 18.0/46

                                   = 0.391 moles

  • moles of 1.35 kg CO_2 = 1350/44

                                         = 30.7 moles

  • moles of 46.1 g KNO_3 = 46.1/101.1

                                          = 0.456 moles

  • moles of 191.8 kg Na_2SO_4 = 191800/142

                                                 = 1350 moles

More on the number of moles of substances can be found here: brainly.com/question/1445383

#SPJ1

5 0
1 year ago
What is the net charge of C
sashaice [31]

Explanation:

Sorry, I don't know, but I can tell you that when an atom, or a body, has the same amount of positive charges (protons) and negative charges (electrons), it is said to be electrically neutral. ... The net charge corresponds to the algebraic sum of all the charges that a body possesses.

5 0
2 years ago
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Consider two solutions: solution x has a ph of 4; solution y has a ph of 7. from this information, we can reasonably conclude th
KIM [24]
<span>Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this information, we can reasonably conclude that </span>the concentration of hydrogen ions (H⁺) or hydronium ions (H₃O⁺) in solution X is thousand times as great as the concentration of hydrogen ions or hydronium ions in solution Y.
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3 0
3 years ago
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