Non-metal atoms gain an electron, or electrons, from another atom to become >negatively charged ions.
However <em>trans</em>-2-Butene does not give a characteristic peak in 1620-1680 cm⁻¹ region but still the presence of carbon double bond carbon can be detected by detecting following peaks in IR Spectrum.
1) 3010-3100 cm⁻¹:
As in trans-2-Butene a hydrogen atoms ate attached to sp² hybridized carbon, therefore the stretching of =C-H (C-H) bond will give a peak of medium intensity in the range of 3010-3100 cm⁻¹.
2) 675-1000 cm⁻¹:
Another peak which is given by the bending of =C-H (C-H) bond with strong intensity will appear in the range of 675-1000 cm⁻¹.
Since you know the ratio of atoms, you can start to put a formula togeter. The formula might look like:<span>
X<span>H2.67
</span></span>but since atoms can't come in fractional amounts, we have to multiply the formula by some number in order to turn 2.67 into a whole #, while still maintaining the ratio. Multiplying 2.67 by 3 yields 8, so the most likely ratio in the molecule is
X3H8<span>so the ratio of 1:2.67 is still maintained. The mass percent tells you that out of every 100g of compound, 91.26g is element X, so the other 8.74g must be H. Dividing each mass by the number of moles in the formula gets us the molar mass of each element (approximately). DIviding 8.74g by 8 gets 1.09, roughly the molar mass of hydrogen. Dividing 91.26g by 3 gets us 30.4, roughly the molar mass of phosphorus. Element X is most likely phosphorus</span>
