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4

According to the standards group ASTM International, octane numbers above 100 are defined using the formula: $$ON=100+\frac{28.28T}{1.0 + 0.736T + (1.0 + 1.472T - 0.035216T^2)^{0.5}}$$ where $T$ is "mL tetraethyllead (TEL) per U.S. gal in isooctane" [1]. This is the standard used by the FTC to regulate automotive fuel ratings in the US [2]. It should be ...


3

First, we have some things to consider and they are: the specific heat of water; the latent heat of vaporization of water; how the terms mentioned above are compared to each other. The specific heat of water is $\pu{4200 J kg-1 K-1}$ and it means that it takes $\pu{4200 kJ}$ amount of heat to increase the temperature of $\pu{1 kg}$ water by $\pu{1 K}.$ On ...


0

Neither of you is correct. The problem is indeterminate assuming that after the reaction the system was brought back to STP because the initial volume of the gas was not specified. If say initially a million liters of oxygen was used then all the water would be present as the vapor. However if a stoichiometric amount of oxygen was used then most, but not all,...


9

I recommend the @Stanley Yu own answer, as I admit I was not particular familiar with the shape of the ON number curve. It is done by an extrapolation of the critical compression ratios of mixtures 0-100% of isooctane and 100-0% of n-heptane for ON values <0 and >100. If, just illustratively, 100% isooctane had the critical compression ratio 1:20, 90% ...


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