How much heat is required to change the temperature of a 15 g aluminum can with 100 g of water from 24.5°C to 55°C?

1 answer:

3 0

Heat capacity of aluminium = 0.900 J/g°C
While heat capacity of water = 4.186 J/g°C
Heat = heat gained by water + heat gained by aluminium
Heat gained by water = 100 × 4.186 × 30.5
= 12767.3 Joules
Heat gained by aluminium = 15 × 0.9 × 30.5
= 411.75 Joules
Heat required = 13179.05 Joules or 13.179 kJoules

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Explain your thoughts on whether or not using solely IR is a good method to make positive IDs of chemicals.

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Answer:

No, IR should not soely be used to identify molecules

Explanation:

IR is a method that identifies the functional groups in a molecule by deducing the frequency of stretching and vibration of bonds. Each peculiar type of bond has a frequency for the vibration of each bond represented on the IR spectrum.

However, one method is never enough to identify a compound. A combination of methods must always be used to clear up ambiguities arising from overlapping IR frequencies. Also, interpretation of the nuanced peaks of the fingerprint region in IR spectra is quite challenging and only gives a fair idea of the functional groups present in the compound.

Therefore other methods such as NMR, UV-VISIBLE etc should also be involved in the identification of compounds.

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Propose a mechanism to account for the formation of a cyclic acetal from 4-hydroxypentanal and one equivalent of methanol. If th

timofeeve [1]

Answer:

If carbonyl oxygen of 4-hydroxypentanal is enriched with $O^{18}$ , then the oxygen label appears in the water .

Explanation:

In the first step, -OH group at C-4 gives intramolecular nucleophilic addition reaction at carbonyl center to produce a cyclic hemiacetal.
Then, one equivalent of methanol gives nucleophilic substitiution reaction by substituting -OH group in cyclic hemiacetal to produce cyclic acetal.
If carbonyl oxygen of 4-hydroxypentanal is enriched with $O^{18}$ , then the oxygen label appears in the water produced at the end of reaction.
Full reaction mechanism has been shown below.