Question

27. Deer ticks are known to cause Lyme disease. The presence of DEET (di- ethyltoluamide) in insect repellents protects the user from the ticks. The mo- lecular formula for DEET is C2H,NO. How many grams of carbon can be obtained from 127 c of DEET?

Answer 1

For a single molecule of DEET(C12H17NO), it contain 12 carbon(C) atoms, 17 hydrogen(H) atoms, 1 nitrogen(N) and 1 oxygen(O) atom.

In terms of moles we can say that one mole of DEET(C12H17NO), it contain 12 moles of carbon(C) atoms, 17 moles hydrogen(H) atoms, 1 mole nitrogen(N) and 1 mole oxygen(O) atom.

Element	Molar Mass(g/mol)
Carbon(C)	12
Hydrogen(H)	1
Oxygen(O)	16
Nitrogen(N)	14

Molar Mass of DEET = 12*Molar Mass of Carbon + 17*Molar Mass of Hydrogen + 1*Molar Mass of Nitrogen + 1*Molar Mass of Oxygen = 12*12+17*1+1*14+1*16 =191g/mol

Moles of DEET = Given Mass / Molar Mass = 127/191 = 0.6649 moles

1 mole of DEET contains 12 moles of carbon atoms, so 0.6649 moles of DEET will contain 0.6649*(12) moles of carbon atoms.

Moles of carbon atoms containing 127g of DEET = 0.6649*12 = 7.979 moles

Mass of carbon containing 127g of DEET = Moles of carbon*Molar Mass of carbon = 7.979*12 = 95.749g

Thereofore 95.749g of carbon can be obtained from 127g of DEET.