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3 years ago

Which is an example of an endothermic reaction?

Chemistry

2 answers:

sertanlavr [38]3 years ago

5 0

The correct answer is C. Photosynthesis.

Explanation

Endothermic reactions are a chemical and physical term used to refer to the process of transformation of two or more substances into different ones, and that particularly consume energy, that is, that the resulting elements have higher energy levels than the initial elements, due to that have taken part of the heat of the environment. According to the above, photosynthesis is an endothermic reaction since plants absorb solar energy, to perform various processes that allow them to make their food, grow and generally live. So, the correct answer is C. Photosynthesis.

Solnce55 [7]3 years ago

4 0

Nuclear explosion i hope that correct

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The diagram below represents a plan cell Letter X represents a structure in the cell

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the cell structure represented by x is the nucleus

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3 years ago

The photoelectric effect occurs when _____ are emitted from metal when the metal is struck by light of certain frequencies.

Ainat [17]

Answer:

electrons

Explanation:

The photoelectric effect occurs when electrons are emitted from metal when the metal is struck by light of certain frequencies.

Some of the applications of this effect include photomultipliers (which are a key component in spectroscopy instruments) and night vision devices.

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3 years ago

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Provide one example of how life on Earth would not be possible without water based on its characteristics.

snow_lady [41]

Answer: ice is less dense than liquid water. If ice was more dense, Earth would freeze.

Explanation: There are many reasons why life on Earth depends on the characteristics of water. One could discuss hydrogen bonds and its role as a solvent, but the unusual property of water is is the change in density with change in temperature. Water is densest at 4 degC, which is why ice floats - it is less dense than cold water (it melts quickly in warm water, so density isn’t impotant at higher temperatures). Most liquids are less dense than the solid, frozen form. If this was the case with water, any ice that formed would sink, and sease would freeze from the bottom up. Furthermore, the lowest layers would be insulated and would not all melt in summer. Thus over time, the seas would become a thin layer of liquid water at best, over solid ice. Life could not develop without liquid seas. In addition, ice is reflective, reducing the amount of sunlight absorbed, further reducing temperatures. Without ocean circulation, polar areas would be even colder, and there would be no rain.

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3 years ago

Karen has a mass of 53 kg as she rides the up escalator at woodley park station of the washington

aivan3 [116]

Vertical height of longest escalator in free world = 58.8 sin 32.4 = 31. 5 m
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3 years ago

Consider the following reaction where Kc = 1.80×10-2 at 698 K:

Klio2033 [76]

Answer:

The system is not in equilibrium and the reaction must run in the forward direction to reach equilibrium.

Explanation:

The reaction quotient Qc is a measure of the relative amount of products and reagents present in a reaction at any given time, which is calculated in a reaction that may not yet have reached equilibrium.

For the reversible reaction aA + bB⇔ cC + dD, where a, b, c and d are the stoichiometric coefficients of the balanced equation, Qc is calculated by:

$Qc=\frac{[C]^{c}*[D]^{d} } {[A]^{a}*[B]^{b}}$

In this case:

$Qc=\frac{[H_{2} ]*[I_{2} ] } {[HI]^{2}}$

Since molarity is the concentration of a solution expressed in the number of moles dissolved per liter of solution, you have:

$[H_{2} ]=\frac{2.09*10^{-2} moles}{1 Liter}$ =2.09*10⁻² $\frac{moles}{liter}$

$[I_{2} ]=\frac{4.14*10^{-2} moles}{1 Liter}$ =4.14*10⁻² $\frac{moles}{liter}$

$[I_{2} ]=\frac{0.280 moles}{1 Liter}$ = 0.280 $\frac{moles}{liter}$

So,

$Qc=\frac{2.09*10^{-2} *4.14*10^{-2} } {0.280^{2} }$

Qc= 0.011

Comparing Qc with Kc allows to find out the status and evolution of the system:

If the reaction quotient is equal to the equilibrium constant, Qc = Kc, the system has reached chemical equilibrium.

If the reaction quotient is greater than the equilibrium constant, Qc> Kc, the system is not in equilibrium. In this case the direct reaction predominates and there will be more product present than what is obtained at equilibrium. Therefore, this product is used to promote the reverse reaction and reach equilibrium. The system will then evolve to the left to increase the reagent concentration.

If the reaction quotient is less than the equilibrium constant, Qc <Kc, the system is not in equilibrium. The concentration of the reagents is higher than it would be at equilibrium, so the direct reaction predominates. Thus, the system will evolve to the right to increase the concentration of products.

Being Qc=0.011 and Kc=1.80⁻²=0.018, then Qc<Kc. The system is not in equilibrium and the reaction must run in the forward direction to reach equilibrium.

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3 years ago