Question
Chemistry Question on Alcohols, Phenols and Ethers
How much gram of ethanol is required to obtain 280 ml dihydrogen at S.T.P by reaction of C2H5OH with Na metal(Mol.wt of ethanol =46 g/mol)?
A
2.3
B
4.6
C
1.15
D
0.575
Answer
1.15
Explanation
Solution
The correct answer is option (C): 1.15
2C2H5OH +2Na → 2C2H5ONa +H2
From the above reaction, we can see that 1 mole of H2 is produced by 2 moles of ethanol. At STP, 1 mole of gas occupies 22.4 L
We have to produce 280ml of dihydrogen, the moles of ethanol required for the same are:
2 moles of ethanol22.4L of H2= 2xmoles of ethanol0.28L of H2
x= 0.025 moles of ethanol.
The mass of ethanol required can be calculated by using the molar mass:
Molar mass of ethanol = 46.08 g/mol
Mass of ethanol required = 0.025 moles x 46.08 g/mol
= 1.152 g
Therefore, the answer is 1.152 g