Passage II
Biodiesel (BD) is a renewable alternative to traditional petroleum diesel (PD). BD is typically prepared by reacting soybean oil with methanol in the presence of a catalyst, forming compounds called fatty acid methyl esters(FAMEs). In contrast, PD contains no FAMEs. The presence of FAMEs in BD causes BD to absorb infrared light differently than does PD. This difference allows pure BD, pure PD, and mixtures of BD and PD to be distinguished by analyzing the absorbance of infrared light.
Students performed 3 studies in which they determined the infrared absorbance characteristics of pure BD, pure PD, and mixtures of BD and PD.
Study 1
The students measured the absorbance, A, of a sample of pure BD and a sample of pure PD at wavenumbers from 600 cm-1 through 1,800 cm-1. The wavenumber corresponding to a given wavelength is defined as
where the wavelength is given in cm and the resulting wavenumber is given in cm-1. They plotted the results for each sample (see Figure 1).
Study 2
The students prepared 7 different mixtures of BD and PD, each containing a different percent by volume of BD. Then, they measured A at 1,746 cm-1 for a sample of each of the 7 mixtures, a sample of pure BD, and a sample of pure PD (see Figure 2).
Study 3
The students obtained 4 different samples of commercial fuel blends of BD and PD (Samples W-Z). They measured A at 1,746 cm-1 for each sample, and then used Figure 2 to calculate the percent BD by volume of each sample (see Table 1).
13. Consider the percent BD by volume listed in Table 1 for Sample Y. A 10 liter (L) volume of Sample Y would contain approximately what volume of BD, in liters and in milliliters (mL) ?
Your Answer is
Correct Answer is A
Explanation
Looking at table 1, the content of BD in Sample Y is 4.8% of the total volume, so 10 L of Sample Y should contain 10×4.8%=0.48 L≈0.5 L of BD;
Conversion Unit 1 L=1000 mL, so 0.5 L=500 mL