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3 years ago

Use Hess's Law or the summation equation to calculate the ΔHrxn. Round to the nearest tenth!!

Chemistry

1 answer:

iren [92.7K]3 years ago

5 0

The ΔHrxn with the nearest tenth will have value of -60 K.

Explanation:

NF(g) + ___F2 (g) --> ___NF2 (g

data given:

½N2 (g) + ½F2 (g) -> NF (g) Hf = 86.6 kJ

½N2 (g) + F2 (g) -> NF2 (g) Hf = 33.8 kJ

Hess's law of heat is summation says that total change in enthalpy during a reaction is same whether the reaction is direct or in various steps.

½N2 (g) + ½F2 (g) -> NF (g) Hf = 86.6 kJ

reversing the equation we get:

NF -> ½N2 (g) + ½F2 (g)

Heat of enthalpy becomes negative so -86.6 KJ

Now adding both the reactions:

NF -> ½N2 (g) + ½F2 (g)

½N2 (g) + F2 (g) -> NF2 (g) Hf = 33.8 kJ

Removing the common entities from the reaction we get

F2 (g) + NF (g) --> ½F2 (g) + NF2 (g) Hf

the summation of enthalpy is

-86.6+ 33.8

= 52.8 KJ

The nearest tenth will be -60 KJ.

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3 years ago

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3 years ago

A tire at 21°C has a pressure of 0.82 atm. Its temperature decreases to –3.5°C. If there is no volume change in the tire, what i

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Explanation :

Gay-Lussac's Law : It is defined as the pressure of the gas is directly proportional to the temperature of the gas at constant volume and number of moles.

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or,

$\frac{P_1}{T_1}=\frac{P_2}{T_2}$

where,

$P_1$ = initial pressure = 0.82 atm

$P_2$ = final pressure = ?

$T_1$ = initial temperature = $21^oC=273+21=294K$

$T_2$ = final temperature = $-3.5^oC=273+(-3.5)=269.5K$

Now put all the given values in the above equation, we get:

$\frac{0.82atm}{294K}=\frac{P_2}{269.5K}$

$P_2=0.752atm$

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Answer:

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3 years ago

Read 2 more answers

Please help!!!!its due tomorrow !!!

scZoUnD [109]

#6).
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want to find the number of ounces in 9-1/2 pounds, you have to take
16 ounces 9-1/2 times .

 (16 ounces) times (9-1/2) = 152 ounces.
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3 years ago