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Which one of the following lists contains only analytical techniques that can be used to determine the concentration of a substance? A - VCE - SSCE Chemistry - Question 1 - 2016 - Paper 1
Question 1
Which one of the following lists contains only analytical techniques that can be used to determine the concentration of a substance? A. AAS, GC and HPLC B. HPLC, G... show full transcript
Worked Solution & Example Answer:Which one of the following lists contains only analytical techniques that can be used to determine the concentration of a substance? A - VCE - SSCE Chemistry - Question 1 - 2016 - Paper 1
Step 1
A. AAS, GC and HPLC
Answer
The techniques listed are:
- AAS (Atomic Absorption Spectroscopy) - This technique is used to determine the concentration of particular metals within a substance. It is effective for trace analysis.
- GC (Gas Chromatography) - This method separates and analyzes compounds that can be vaporized without decomposition. It is often used in drug testing and environmental analysis.
- HPLC (High-Performance Liquid Chromatography) - This technique is used for separating, identifying, and quantifying compounds in a mixture, making it highly effective for concentration determination.
Since all three techniques can accurately be used for determining concentration, this option is valid.
Step 2
B. HPLC, GC and TLC
Answer
This option includes:
- HPLC - Already established as valid for concentration determination.
- GC - Already established as valid for concentration determination.
- TLC (Thin Layer Chromatography) - While TLC is useful for separating compounds, it is generally less quantitative than HPLC and GC, often used for qualitative analysis. Thus, this option does not entirely meet the criteria.
Step 3
C. UV-vis and 1H NMR
Answer
The discussed techniques are:
- UV-vis (Ultraviolet-Visible Spectroscopy) - This method allows for concentration determination, particularly for compounds that absorb UV or visible light.
- 1H NMR (Proton Nuclear Magnetic Resonance) - Though primarily qualitative, it can provide concentration information through integration; however, it is not primarily a quantitative method for concentration determination.
Considering 1H NMR’s limitations for concentration as a standard, this option is not valid.
Step 4
D. UV-vis, AAS and TLC
Answer
The techniques here are:
- UV-vis - Effective for concentration determination.
- AAS - Effective for concentration determination.
- TLC - As previously noted, while useful for separation, it is less reliable for quantitative analysis. Thus, this option does not fully meet the requirement for concentration determination.