- #1
Lindsayyyy
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Hi everybody,
sorry for my sloppy english. I have to translate the task so if you don't understand something just tell me and I try to rephrase it.
The exersice is about the "Knallgas" equation. Two reaction euqations are given:
[tex] 2H + O \xrightarrow \ 2H_2O +\Delta E[/tex]
and
[tex] 2H_{2} + O_{2} \xrightarrow \ 2H_{2}O +2\Delta E[/tex]
The energy which is released in this equation is: dE=285.8kJ
a) Decide which reaction equation is the right one. The decision should be based on experimental obseravtions.
b) How much grams oxygen is needed for an optimal reaction when I have 0.0038 cm³ hydrogen?
c) How much energy is released? How long could someone use that energy to run a hairdryer with it (P=1,2 kW)
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a) Well, I think I can discuss that problem using the theorem from Avogrado. The ratio is the same in both equations. But in my opinion the task is missing a value for the volume of the water. But I say that the 2nd equation is right (That's what someone would find in the experiment)
b) I searched for the density of H2
[tex] \rho \cdot V=m [/tex]
I get m=3.42*10^-4 kg
also
[tex] \frac {m(H_2)} {m(O_2)}= \frac 1 8[/tex]
Now I just have to multiply the mass of H2 times 8 in order to get the mass from O2. I get m(O2)=2.73*10^-3kg
c) I use the law of conservation of mass. The whole mass of water equals m(H2)+m(O2). I searched for the molar mass of water in order to calculate how much mol I have. Afterwards I calculate the energy the following way:
E= E(given)*mol
and for the last task I used the formula: P=dE/dt
Is my solution right? Are there other possibilities to solve it? I'm uncertain because I had to look up some stuff like molecular weight, density etc. But I don't know if there's another way
Thank you for your help in advance
sorry for my sloppy english. I have to translate the task so if you don't understand something just tell me and I try to rephrase it.
Homework Statement
The exersice is about the "Knallgas" equation. Two reaction euqations are given:
[tex] 2H + O \xrightarrow \ 2H_2O +\Delta E[/tex]
and
[tex] 2H_{2} + O_{2} \xrightarrow \ 2H_{2}O +2\Delta E[/tex]
The energy which is released in this equation is: dE=285.8kJ
a) Decide which reaction equation is the right one. The decision should be based on experimental obseravtions.
b) How much grams oxygen is needed for an optimal reaction when I have 0.0038 cm³ hydrogen?
c) How much energy is released? How long could someone use that energy to run a hairdryer with it (P=1,2 kW)
Homework Equations
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The Attempt at a Solution
a) Well, I think I can discuss that problem using the theorem from Avogrado. The ratio is the same in both equations. But in my opinion the task is missing a value for the volume of the water. But I say that the 2nd equation is right (That's what someone would find in the experiment)
b) I searched for the density of H2
[tex] \rho \cdot V=m [/tex]
I get m=3.42*10^-4 kg
also
[tex] \frac {m(H_2)} {m(O_2)}= \frac 1 8[/tex]
Now I just have to multiply the mass of H2 times 8 in order to get the mass from O2. I get m(O2)=2.73*10^-3kg
c) I use the law of conservation of mass. The whole mass of water equals m(H2)+m(O2). I searched for the molar mass of water in order to calculate how much mol I have. Afterwards I calculate the energy the following way:
E= E(given)*mol
and for the last task I used the formula: P=dE/dt
Is my solution right? Are there other possibilities to solve it? I'm uncertain because I had to look up some stuff like molecular weight, density etc. But I don't know if there's another way
Thank you for your help in advance