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.
Answer:
B. adding heat to the system and having the system do work on the surroundings
Explanation:
The internal energy of a system is the energy contained within the system. From first law of thermodynamics we have the equation : dq=du+dw
and we know that energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another therefore du is zero. dq = dw this means that the entire heat supplied is converted into work (on the surroundings)
However, some of the heat supplied is also used to increase the internal energy of the system
Answer:
History of composition
Years Material Weight (grains)
1944–1946 gilding metal (95% copper, 5% zinc) 48 grains
1947–1962 bronze (95% copper, 5% tin and zinc) 48 grains
1962 – September 1982 gilding metal (95% copper, 5% zinc) 48 grains
October 1982 – present copper-plated zinc (97.5% zinc, 2.5% copper) 38.6 grains
Answer:
588.2 mL
Explanation:
- FeSO₄(aq) + 2KOH(aq) → Fe(OH)₂(s) + K₂SO₄(aq)
First we <u>calculate how many Fe⁺² moles reacted</u>, using the given <em>concentration and volume of FeSO₄ solution</em> (the number of FeSO₄ moles is equal to the number of Fe⁺² moles):
- moles = molarity * volume
- 187 mL * 0.692 M = 129.404 mmol Fe⁺²
Then we convert Fe⁺² moles to KOH moles, using the stoichiometric ratios:
- 129.404 mmol Fe⁺² *
= 258.808 mmol KOH
Finally we<u> calculate the required volume of KOH solution</u>, using <em>the given concentration and the calculated moles</em>:
- volume = moles / molarity
- 258.808 mmol KOH / 0.440 M = 588.2 mL
