Question

In the reaction
$ROH+PB{r}_3\to RBr$
The number of moles of alcohol that may be converted into alkyl bromide by one mole of $PB{r}_3$ is:
1 mole
2 mole
3 mole
None of the above

Answer 1

Hint: A mole of a substance or particles can be defined as exactly $6.02214076\times {10}^{-23}$ number of particles present in it those particles may be molecules, ions, atoms or electrons. However, $1mole=6.022\times {10}^{23}$.

Complete Step by step explanation: Mass of the substance which consists of the equal quantity of basic units is defined as the mole. For example atoms in 12 grams are the same as 12C. The basic units can be molecules, atoms or formula units based on the substance. It can be used to find the products obtained from the chemical reaction. The unit is denoted by mol. Alcohols are those substances which contain $$OH$$ group and end with ol like methanol, ethanol, propanol etc. Phosphorus tribromide is a colorless liquid with the formula $PB{r}_3$. The liquid fumes present in moist air is due to hydrolysis and has a penetrating odor. It is used in the laboratory for the conversion of alcohols to alkyl bromides.
Let us discuss the chemical equation
$3ROH+PB{r}_3\to 3RBr+H_{3}P{O}_3$
In this reaction we can find that 1 mole of $ROH$ reacts with 1 mole of $PB{r}_3$ to form 1 mole of $RBr$.

Thus, 1 mole of alcohol is required to convert into alkyl bromide by one mole of $PB{r}_3$.

Note: This reaction is generally used for the conversion of alcohols $$R-OH$$ into alkyl bromides $R-Br$. $PB{r}_3$ can be prepared by treating red phosphorus with bromine. This reaction is highly exothermic in nature i.e. a large amount of heat evolved during the reaction.