HardChemistryHigh School (11–12)Organic Compounds with Functional Groups › Haloalkanes and HaloarenesNumerical
Meera prepares 1-bromobutane by warming butan-1-ol with sodium bromide and concentrated sulphuric…
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Meera prepares 1-bromobutane by warming butan-1-ol with sodium bromide and concentrated sulphuric acid, as in the preparation of a primary bromide. The sulphuric acid is in excess and releases hydrogen bromide in the flask. She uses of butan-1-ol and of sodium bromide. The molar masses are for butan-1-ol, for sodium bromide and for 1-bromobutane. After distilling and drying, she collects of 1-bromobutane. One mole of alcohol gives one mole of the bromide. Find the amount of the limiting reagent, the theoretical mass of 1-bromobutane and the percent yield.
Need a reminder? The key ideaShow
The dipole moment of a bond is the charge multiplied by the bond length, . One debye is . Boiling points of an unbranched series rise by nearly the same amount for each extra carbon atom. Percent yield is .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. Compare the amounts, take the smaller, find the mass it could give, then compare it with the mass collected.
Step 1. Amounts. Butan-1-ol: . Sodium bromide: .
Step 2. Limiting reagent. The ratio is 1 : 1, so the butan-1-ol limits the reaction at . Sodium bromide is in slight excess.
Step 3. Theoretical mass. .
Step 4. Percent yield. .
Answer: of butan-1-ol limits the reaction. The theoretical mass is and the yield is .
Check. The yield is below 100 percent, as it must be. Some product is lost as ether, as alkene and in the transfers.
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