First Mid nots bank tr Print calculator Periodic Table Question 2 of 25 Sapling

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First Mid nots bank tr Print calculator Periodic Table Question 2 of 25 Sapling Learning A HNMR signal is observed at 145.0 Hz (downfield of TMS) on a 145-MHz instrument a) What is the observed chemical shift in parts per million (ppm)? ppm b) What is the chemical shift, in parts per million (ppm). if the sample is analyzed with a 200.0 MHz instrument? ppm c) Where will the proton signal appear in hertz, if the sample is analyzed with a 200.0 MHz instrument? Number Hz O Previous ® Give up s vow sea icom Check Answer 0 Next Exit "L Hint

Explanation / Answer

a) ppm = ( observd frequency x 10^ 6 ) / ( instrument frequency in Hz)

      = ( 145 Hz x 10^ 6 ) / ( 145x10^6 Hz)      ( sinstrument freequency = 145 MHz = 145 x 10^6 Hz

= 1ppm

b) chemical shift value is independant of spectrometer frequency

hence chemical shift = 1 ppm

c)   1ppm = ( oberved frequency x 10^6 ) / ( 200 x 10^ 6 Hz)

oberved frequency = 200 Hz

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