Question

22. Calculate the molar mass of the following
i. Ethanol (C2H5OH)
ii. Sucrose (C12H22011)
23. Calculate the number of moles present in 9g of ethane​

Answer 1

Answer:

1) C2H5OH = (12×2)+ (1×5)+ (16×1) =24+5+16= 45 molar gram. 2) C12H22O11 = (12×12) + (1×22) + (16×11) = 144+22+176 = 342 molar gram

Answer 2

22.

Given:

i. Ethanol ($\[{C_2}{H_5}OH\]$)

ii. Sucrose ($\[{C_{12}}{H_{22}}{O_{11}}\]$)

To Find: Molar mass of ethanol and sucrose

Solution:

Molar mass can be calculated by adding the atomic masses of all the elements present in a given compound.

Therefore,

Molar mass can be given as:

i. Ethanol ($\[{C_2}{H_5}OH\]$)

$\[{C_2}{H_5}OH:\,2 \times 12 + 5 \times 1 + 16 \times 1 + 1 \times 1 = 46\,g/mol\]$

ii. Sucrose ($\[{C_{12}}{H_{22}}{O_{11}}\]$)

$\[{C_{12}}{H_{22}}{O_{11}}:\,12 \times 12 + 22 \times 1 + 11 \times 16 = 342\,g/mol\]$

Hence, the molar masses of ethanol and sucrose are 46 g/mol and 342 g/mol respectively.

23.

Given:

Mass of ethane $=9g$

To Find: Number of moles present in 9 g of ethane​

Solution:

Number of moles can be given as:

$\[No.\,of\,moles = \frac{{Mass}}{{Molar\,mass}}\]$

$\[No.\,of\,moles = \frac{{9\,g}}{{30\,g/mol}}\]$

$\[No.\,of\,moles = 0.3\,mol\]$

Hence, the number of moles present in 9 g of ethane​ is 0.3 mol.