The water in a pressure cooker boils at a temperature greater than 100°C because it is under pressure. At this higher temperature, the chemical reactions associated with the cooking of food take place at a greater rate. (a) Some food cooks fully in 7.00 min in a pressure cooker at 113.0°C and in 49.0 minutes in an open pot at 100.0°C. Calculate the average activation energy for the reactions associated with the cooking of this food. kJ mol-1 (b) How long will the same food take to cook in an open pot of boiling water at an altitude of 10000 feet, where the boiling point of water is 89.8 °C? min

Respuesta :

Answer:

the activation energy Ea = 179.176 kJ/mol

it will take  7.0245 mins for the same food to cook in an open pot of boiling water at an altitude of 10000 feet.

Explanation:

From the given information

[tex]T_1 = 100^0 C = 100+273 = 373 \ K \\ \\ T_2 = 113^0 C = 113 + 273 = 386 \ K[/tex]

[tex]R_1 = \dfrac{1}{7}[/tex]

[tex]R_2 = \dfrac{1}{49}[/tex]

Thus; [tex]\dfrac{R_2}{R_1} = 7[/tex]

Because at 113.0°C; the rate is 7 time higher than at 100°C

Hence:

[tex]In (7) = \dfrac{Ea}{8.314}( \dfrac{1}{373}- \dfrac{1}{386})[/tex]

1.9459 = [tex]\dfrac{Ea}{8.314}* 9.0292 *10^{-5}[/tex]

[tex]1.9459*8.314 = Ea * 9.0292*10^{-5}[/tex]

[tex]16.1782126= Ea * 9.0292*10^{-5}[/tex]

[tex]Ea = \dfrac{16.1782126}{ 9.0292*10^{-5}}[/tex]

Ea = 179.176 kJ/mol

Thus; the activation energy Ea = 179.176 kJ/mol

b)

here;

[tex]T_2 = 386 \ K \\ \\T_1 = (89.8 + 273)K = 362.8 \ K[/tex]

[tex]In(\dfrac{R_2}{R_1})= \dfrac{Ea}{R}(\dfrac{1}{T_1}- \dfrac{1}{T_2})[/tex]

[tex]In(\dfrac{R_2}{R_1})= \dfrac{179.176}{8.314}(\dfrac{1}{362.8}- \dfrac{1}{386})[/tex]

[tex]In (\dfrac{R_2}{R_1}) = 0.00357[/tex]

[tex]\dfrac{R_2}{R_1}= e^{0.00357}[/tex]

[tex]\dfrac{R_2}{R_1}= 1.0035[/tex]

where ;

[tex]R_2 = \dfrac{1}7{}[/tex]

[tex]R_1 = \dfrac{1}{t}[/tex]

Now;

[tex]\dfrac{t}{7}= 1.0035[/tex]

t = 7.0245 mins

Therefore; it will take  7.0245 mins for the same food to cook in an open pot of boiling water at an altitude of 10000 feet.

a). The activation energy given by the reactions related to the cooking of food in the pressure cooker would be:

[tex]Ea = 179.176 kJ/mol[/tex]

b). The time duration that is taken by the same food to cook in an open vessel would be:

[tex]7.0245 mins[/tex]

Activation Energy

a). Given that,

Temperature [tex]1[/tex]  [tex]= 100[/tex]° C

Temperature [tex]2[/tex] [tex]= 113[/tex]° C

In Kelvin,

Temperature  [tex]1[/tex] [tex]= 100 + 273[/tex]

[tex]= 373 K[/tex]

Temperature  [tex]2[/tex] [tex]= 113 + 273[/tex]

[tex]= 386 K[/tex]

[tex]R_{1} = 1/7\\R_{2} = 1/49[/tex]

∵ [tex]R_{2}/R_{1} = 49/7 = 7[/tex]

It is given that at  [tex]113[/tex] rate [tex]=[/tex] [tex]7[/tex] × [tex]100[/tex]°C

Therefore,

[tex]Ea/8.314 (1/373 - 1/386) =[/tex] [tex]In(7)[/tex]

so,

[tex]Ea[/tex] [tex]= 16.1782126/(9.0292 * 10^{-5})[/tex]

Activation energy [tex]= 179.176 kJ/mol[/tex]

b). As we know,

[tex]T_{2}[/tex] [tex]= 386 K[/tex]

[tex]T_{1}[/tex] [tex]= (89. 8 + 273)[/tex]

[tex]= 362.8 K[/tex]

by employing the formulae,

[tex]In(\frac{R_{2} }{R_{1} }) = \frac{Ea}{R} (1/T_{1} - 1/T_{2})[/tex]

[tex]In(\frac{R_{2} }{R_{1} }) = 179.176/8.314 (1/362.8 - 1/386)[/tex]

By solving this, we get

[tex]R_{2}/R_{1} = 1.0035[/tex]

Thus,

[tex]R_{2} = 1/7[/tex]

[tex]R_{1} = 1/t[/tex]

∵ t [tex]= 7.0245 min[/tex]

Thus, the time duration would be [tex]7.0245 minutes[/tex].

Learn more about "Boiling Point" here:

brainly.com/question/2153588