Question

1. Concept of limiting reagent. A magician can combine 1 pink rose and 1 white rose and convert them into a purple rose and an apple. If he is given 100 pink roses and 331 white roses, and his conversion yield is 100%, how many purple roses and apples can he get?

2. Cont’d Problem 1. If his conversion yield is 90%, how many purple roses and apples can he get?

3. Assume 100% conversion yield again, what if he is given 999 pink roses and 99 white roses, how many purple roses and apples can he get?

4. A chemist runs the following reaction. (You may need to use a calculator)

nBuCl + NaI --> nBuI + NaCl

nBu = n-butyl = CH₃CH₂CH­­₂CH₂-

He is given 0.49 g of BuCl, and 3.1 g of NaI, and he obtained 0.65 g of nBuI. What is the yield of the reaction?

5. Draw all the stereoisomers of PhBrCHCHBrPh. Extra identical ones will result in loss of credit.

6. Provide the products with correct stereochemistry for

cis-stilbene + pyridinium tribromide -->

(It is highly recommended that you be able to draw out the mechanism of the reaction.)

Answer 1

1) limiting reagent in this solution 1 pink combine with 1 white rose to produced 1 purpel rose and 1 apple

so 100 pink rose cobine 100 white rose but white rose is 331

so limiting reagent is pink rose and 100 combine to form 100 apple and 100 purple rose

2) if 90 % conversion

100 limiting reagent / total percentage maxi (100) x 90 = 90 purple rose and 90 apple

3) 100 % conversion

99 white rose and 999 pink rose

white rose is limiting reagent so 99 purple and 99 apple will product

4)

nBuCl + NaI --> nBuI + NaCl

nBu = n-butyl = CH3CH2CH­­2CH2-

He is 0.49 g of BuCl, and 3.1 g of NaI, and he obtained 0.65 g of nBuI.no of mole of H =0.49 mole and NaI = 0.0043 mole and BuI = 0.00353 mole

no of hydrogen atoms in 1 mole reaction 9 atoms so mole = 0.054 mole so product will be bu limiting reagent so 0.00353 mole of product formed