Select all of the following equations that represent an exothermic reaction.

1 answer:

3 0

Exothermic reactions:

1) release heat to the surroundings

2) the change of enthalpy, ΔH, is negative: ΔH < 0

3) the temperature of the system increases

With that you can conclude about every equation given:

<span>NH3(g) + 12.0 kcal → ½N2(g) + 3/2 H2(g) : is not exothermic because heat in the side of the reactants means that heat is being used, not released.

C(graphite) → C(diamond), ΔH = - 0.45 kcal : is exothermic because ΔH is negative

C + 2S → CS2, ΔH = 27,550 cal: is not exothermic because ΔH is positive

CH4 + 2O2 → CO2 + 2H2O + 212,800 cal : is exothermic because heat appears as a product of the reaction, which means that it is released.

2H2O → 2H2 + O2, ΔH = +58 kcal : is not exothermic because ΔH is positive.</span>

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Answer:

Answer: 882mmHg

Explanation:

In a closed-end manometer, the gas added is under a pressure that is measured against atmospheric pressure. The difference in pressure between both gases is equal to the difference in mercury levels. Thus, the pressure of the argon can be:

783 mmHg - 96.0mmHg = 687mmHg

783 mmHg - 96.0mmHg = 879mmHg

Based on the options, the possible answer (The nearest to the second value) is:

<h3>Answer: 882mmHg</h3>

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The answer is the coefficient is "1".
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Brut [27]

Answer is 67.8%

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Magnesium chloride, MgCl2, is an important industrial chemical.

gavmur [86]

This problem is providing information about a reaction between magnesium and hydrochloric acid. However, the moles of the latter are required given 50 cm³ of a 0.2-M solution, making this problem more about the application of molarity. At the end, the answer turns out to be 0.01 mol.

<h3>Molarity:</h3>

In chemistry, we use units of concentration in order to represent the relative amounts of solute and solvent in a solution. More specifically, molarity relates the moles of the solute with the liters of solution according to:

$M=\frac{n}{V}$

Thus, since this problem asks for the moles of hydrochloric acid in 50 cm³ of a 0.2-M solution, we must first calculate the volume in liters with:

$V=50cm^3*\frac{1L}{1000cm^3} =0.050L$

To finally solve for n, moles, to obtain:

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Learn more about molarity: brainly.com/question/9468209

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