DP Chemistry (last assessment 2024)

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Question 18M.3.sl.TZ2.3c.i

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.3.sl.TZ2.3c.i
Level sl Paper 3 Time zone TZ2
Command term Identify Question number c.i Adapted from N/A
c.i.
[Maximum mark: 2]
18M.3.sl.TZ2.3c.i

Inductively Coupled Plasma (ICP) used with Mass Spectrometry (MS) or Optical Emission Spectrometry (OES) can be used to identify and quantify elements in a sample.

The following graphs represent data collected by ICP-OES on trace amounts of vanadium in oil.

Graph 1: Calibration graph and signal for 10 μg kg−1 of vanadium in oil

Graph 2: Calibration of vanadium in μg kg−1

[Source: © Agilent Technologies, Inc.1998. Reproduced with Permission, Courtesy of Agilent Technologies, Inc.]

(c.i)

Identify the purpose of each graph.

 

[2]

Markscheme

Graph 1: determines wavelength of maximum absorption/maximum intensity «for vanadium»

 

Graph 2: determines absorption of known concentrations «at that wavelength»

OR

estimates [V]/concentration in a sample using «the signal» intensity

 

Do not accept just “determines maximum wavelength/λmax” for M1.

Do not accept “calibration curve” for M2.

[2 marks]

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