Question

calculate the molecular mass of the following 1)NH3 2)CH3COOH 3)C2H5OH (average atomic mass of N=4,O=16,H=1,C=12​

Answer 1

QUESTION : calculate the molecular mass of the following 1)NH3 2)CH3COOH 3)C2H5OH (average atomic mass of N=14 , O=16,H=1,C=12

To find : molecular mass of given compounds

Method used : molecular mass is sum of average atomic mass of each element

Solution :

1) NH3

• molecular mass of NH3 = average atomic mass of N + 3×(average atomic mass of H) { as there are three hydrogen atoms so we have to multiply average atomic mass of H by 3}
• molecular mass of NH3 = 14 + 3×(1)
• molecular mass of NH3 = 17g

2) CH3COOH

• molecular mass of CH3COOH = average atomic mass of C + 3×(average atomic mass of H) + average atomic mass of C + 2×(average atomic mass of O) + average atomic mass of H
• molecular mass of CH3COOH = 12 + 3×(1) + 12 + 2×(16) + 1
• molecular mass of CH3COOH = 12+3+12+32+1
• molecular mass of CH3COOH = 60g

3) C2H5OH

• molecular mass of C2H5OH = 2×(average atomic mass of C) + 5×(average atomic mass of H) + average atomic mass of O + average atomic mass of H
• molecular mass of C2H5OH = 2×(12) + 5×(1) + 16 + 1
• molecular mass of C2H5OH = 24+5+16+1
• molecular mass of C2H5OH = 46g

ANSWER :

1) NH3 = 17g

2) CH3COOH = 60g

3) C2H5OH = 46g