Philosophy to Chemistry to Elucidation

Logic Puzzle #26: Elemental Analysis to Empirical Formula … Solution

The results for calculating the empirical formula for an unknown compound using data from elemental analysis are presented.

An elemental analysis was collected for an unknown organic compound. A 0.30 g sample of the unknown was burned to completion and it gave 59.6 % C, 6.9 % H and 8.7 % N. The results are summarized in the table below. The calculation for the unknown organic compound assumes that the missing % composition is oxygen.

Atom moles = Composition * Sample Mass / Atomic Weight (1)

Atom	Composition (%)	Sample Mass (g)	Atomic Weight (g/mol)	Formula 1 (mol)	Mol Ratio (/ 0.186)	Mol Ratio (X 2)
C	59.6	0.30	12.0107	1.489	8.01	16.01
H	6.9	0.30	1.0079	2.057	11.06	22.12
N	8.7	0.30	14.0067	0.186	1.00	2.00
O	24.8	0.30	15.9994	0.465	2.50	5.00

Using formula 1, the Mol ratios are calculated. Dividing by the smallest value (0.186) and then multiplying by 2, the empirical formula for the unknown is C16 H22 N2 O5.

To determine the molecular formula for the unknown, additional information such as the molecular weight is necessary.

Logic Puzzle #26: Elemental Analysis to Empirical Formula

Elemental analysis is an experiment used to determine the elemental composition of an unknown compound. The purpose of this puzzle is to use the percentage composition data from elemental analysis to deduce an empirical formula.

An elemental analysis was collected for an unknown organic compound. A 0.30 g sample of the unknown was burned to completion and it gave 59.6 % C, 6.9 % H and 8.7 % N. What is the empirical formula of the unknown?

Logic Puzzle #25: Zero Filling at its Best … Solution

For each increment of zero filling, the number of data points defining a line shape is increased. The trade-off is the size of the FID increases proportionately. An FID with 1K = 1024 points will produce a file of ~ 50 kb (including data parameters). The goal is to balance the file size with the amount of gain from applying zero filling.

Spectra A and B appeal aesthetically due to the higher level of smoothness across the signals. Whereas the original data, spectrum E, is jagged and presents less than ideal line shapes.

Analysts typically apply 1 to 2 zero fillings; this equates to adding respectively 1 to 2 increments of zeroes equal to the number of data points.

Blog on Hiatus for the Holidays

As the holidays approach, I will be home resting with my family. The blog Philosophy to Chemistry to Elucidation will be on hiatus from December 19^th to January 6^th.

I want to wish the readers of P2C2E Happy Holidays. Stay tuned for the solution for the Logic Puzzle # 25 in the New Year.

Logic Puzzle #25: Zero Filling at its Best

Zero filling is the process of adding a string of zeroes to the end of an FID. The following puzzle aims at understanding how zero filling impacts the line shape of a doublet.

The following 1H NMR spectrum was collected with a total of 4K points (selective region is shown as spectrum E). Applying different amounts of zero filling will modify the line shape of the doublet. Which spectrum(a) offers visually the best line shape for the doublet?