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erma4kov [3.2K]
4 years ago
12

In an exothermic reaction:_________ A. The surroundings absorb heat from the reaction mixture. B. The surroundings release heat

to the reaction mixture.
Chemistry
1 answer:
Elis [28]4 years ago
7 0

Answer: option A. The surroundings absorb heat from the reaction mixture

Explanation:

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Calculate the standard enthalpy of formation of NOCl(g) at 25 ºC, knowing that the standard enthalpy of formation of NO(g) at th
stepan [7]

Answer:

The standard enthalpy of formation of NOCl(g) at 25 ºC is 105 kJ/mol

Explanation:

The ∆H (heat of reaction) of the combustion reaction is the heat that accompanies the entire reaction. For its calculation you must make the total sum of all the heats of the products and of the reagents affected by their stoichiometric coefficient (number of molecules of each compound that participates in the reaction) and finally subtract them:

Enthalpy of the reaction= ΔH = ∑Hproducts - ∑Hreactants

In this case, you have:  2 NOCl(g) → 2 NO(g) + Cl₂(g)

So, ΔH=2*H_{NO} +H_{Cl_{2} }-2*H_{NOCl}

Knowing:

  • ΔH= 75.5 kJ/mol
  • H_{NO}= 90.25 kJ/mol
  • H_{Cl_{2} }= 0 (For the formation of one mole of a pure element the heat of formation is 0, in this caseyou have as a pure compound  the chlorine Cl₂)
  • H_{NOCl}=?

Replacing:

75.5 kJ/mol=2* 90.25 kJ/mol + 0 - H_{NOCl}

Solving

-H_{NOCl}=75.5 kJ/mol - 2*90.25 kJ/mol

-H_{NOCl}=-105 kJ/mol

H_{NOCl}=105 kJ/mol

<u><em>The standard enthalpy of formation of NOCl(g) at 25 ºC is 105 kJ/mol</em></u>

8 0
3 years ago
Chromium (Cr) can combine with chlorine (Cl) to form chromium chloride (CrCl3).
lisov135 [29]
2 Cr + 3 Cl2 ------> 2CrCl3
7 0
3 years ago
A steel container with a movable piston contains 2.00 g of helium which was held at a constant temperature of 25 °C. Additional
shtirl [24]

Answer: D) 1.00 g

Explanation:

According to the Avogadro's law, the volume of gas is directly proportional to the number of moles of gas at same pressure and temperature. That means,

V\propto n

or,

\frac{V_1}{V_2}=\frac{n_1}{n_2}

where,

V_1 = initial volume of gas  = 2.00 L

V_2 = final volume of gas = 3.00 L

n_1 = initial moles of gas  =\frac{\text {Given mass of helium}}{\text {molar mass of helium}}=\frac{2.00g}{4g/mol}=0.500mol

n_2 = final moles of gas  = ?

Now we put all the given values in this formula, we get

\frac{2.00L}{3.00L}=\frac{0.500mol}{n_2}

n_2=0.75mole

Mass of helium =moles\times {\text {molar mass}}=0.75\times 4=3.00g

Thus mass of helium added = (3.00-2.00) g = 1.00 g

4 0
3 years ago
Which of these compounds are molecular?<br> CBr4<br> FeS<br> P4O6<br> PbF2
olasank [31]

Answer:

I think it's answer is P4O6

I hope it's helpful for you...

8 0
3 years ago
Electro magnetic waves are blank waves<br><br> What’s the blank PLEASE HELP DUE IN 25 MINUTES!!!!
Sav [38]

Answer:

Electromagnetic waves or EM waves are waves that are created as a result of vibrations between an electric field and a magnetic field. Hope it helps ;)

3 0
4 years ago
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