Answer:
The heat released by the combustion is 20,47 kJ
Explanation:
Bomb calorimeter is an instrument used to measure the heat of a reaction. The formula is:
Q = C×m×ΔT + Cc×ΔT
Where:
Q is the heat released
C is specific heat of water (4,186kJ/kg°C)
m is mass of water (1,00kg)
ΔT is temperature change (23,65°C - 20,45°C)
And Cc is heat capacity of the calorimeter (2,21kJ/°C)
Replacing these values the heat released by the combustion is:
<em>Q = 20,47 kJ</em>
Nonane (b) has the highest melting point.
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A caveat: I'm assuming that we're dealing with the straight-chain isomers of these alkanes (specifically pentane and nonane). The straight-chain isomer of pentane (<em>n</em>-pentane, CH3-[CH2]3-CH3) has a melting point of -129.8 °C; the straight-chain isomer of nonane (<em>n-</em>nonane, CH3-[CH2]7-CH3) has a melting point of -53.5 °C. The pattern holds as you go down (or up): The more carbon atoms, the higher the melting point. So, in decreasing order of melting points here, you'd have the following: nonane > pentane > butane > ethane.
However, one structural isomer of pentane, neopentane, has a melting point of -16.4 °C, which is <em>higher </em>that the melting point of <em>n</em>-nonane despite neopentane having the same molecular formula as its straight-chain isomer. Of course, you're not to blame for coming up with this question; this is just some extra info to keep in mind.
