Question

Calculate the Molecular Masses of: $\sf{H_2O}$,$\sf{0_2}$,$\sf{Cl_2}$,$\sf{CO_2}$,$\sf{CH_4}$,$\sf{C_2H_6}$,$\sf{C_2H_4}$,$\sf{NH_3}$ and $\sf{CH_3OH}$.​

Answer 1

ANSWER

• The total sum of the masses of the atoms or elements present in the molecule is termed as molecular mass.

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I) Molecular mass of H20 = Atomic mass of H + 2 × Atomic mass of O

= 1+ 2× 16

molecular mass of H20 = 48u

II) Molecular mass of O2= 2 x Atomic mass of O

= 2 x 16

Molecular mass of O2= 32 u

III) Molecular mass of Cl2= 2 x Atomic mass of Cl

= 2 x 35.5

Molecular mass of Cl2 = 71 u

IV) Molecular mass of CO2= Atomic mass of C + 2 x Atomic mass of O

= 12 + 2 x 16

Molecular mass of CO2 = 44 u

v) Molecular mass of CH4= Atomic mass of C + 4 x Atomic mass of H

= 12 + 4 x 1

Molecular mass of CH4 = 16 u

vi) Molecular mass of C2H6= 2 x Atomic mass of C + 6 x Atomic mass of H

= 2 x 12 + 6 x 1

Molecular mass of C2H6 = 30 u

vii) Molecular mass of C2H4= 2 x Atomic mass of C + 4 x Atomic mass of H

= 2 x 12 + 4 x 1

Molecular mass of C2H4 = 28 u

viii) Molecular mass of NH3= Atomic mass of N + 3 x Atomic mass of H

= 14 + 3 x 1

Molecular mass of NH3 = 17 u

ix) Molecular mass of CH3OH= Atomic mass of C + 4 x Atomic mass of H + 1 x Atomic mass of

= 12 + 4 x 1 + 16

Molecular mass of CH3OH = 32 u

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Answer 2

Answer:

$\mathrm{{(i) \: To \: Calculate \: the \: Molecular \: Masses \: of: \: H_2O }} \\ \\ \mathrm{Molecular \: Masses \: of \: \: H_2O } \ \\ \tiny\sf \pink{(atomic \: mass \: of \: hydrogen \: = 1 u\: and \: \: oxgyen \: = 16u )} \\ \mathrm{Molecular \: Mass \: of \: \: H_2O:\: \: 2(1) + 16 } \\ \mathrm{Molecular \: Mass \: of \: H_2O: \: \: 2+ 16u } \\ \boxed{ \mathrm{Molecular \: Mass \: of \: \: H_2O \: : \: \: \: 18u }}$

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$\purple{\mathrm{{(ii) \: To \: Calculate \: the \: Molecular \: Masses \: of: \: O_2}}} \\ \\ \purple{\mathrm{Molecular \: Masses \: of \: \: O_2 }} \ \\ \tiny\sf(atomic \: mass \: of \: \: \: oxgyen \: = 16u ) \\ \purple{\mathrm{Molecular \: Mass \: of \: \: O_2:\: \: 2 (16) }} \\ \purple{ \mathrm{Molecular \: Mass \: of \: O_2: \: \: 32u }} \\ \purple{ \boxed{ \mathrm{Molecular \: Mass \: of \: \: O_2 \: : \: \: \: 32u }}}$

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$\pink{\mathrm{{(iii) \: To \: Calculate \: the \: Molecular \: Masses \: of: \: Cl_2 }} }\\ \\ \pink{\mathrm{Molecular \: Masses \: of \: \:Cl_2 } }\ \\ \tiny\sf {(atomic \: mass \: of \: chlorine \: = 35.5u )} \\ \pink{ \mathrm{Molecular \: Mass \: of \: \: Cl_2:\: \: 2(35.5)}} \\ \pink{ \mathrm{Molecular \: Mass \: of \:Cl_2: \: \: 71u } } \\ \pink{ \boxed{ \mathrm{Molecular \: Mass \: of \: \: Cl_2\: : \: \: \: 71u }}}$

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$\blue{\mathrm{{(iv) \: To \: Calculate \: the \: Molecular \: Masses \: of: \: CO_2 }} }\\ \\ \blue{\mathrm{Molecular \: Masses \: of \: \:CO_2 } }\ \\ \tiny\sf {(atomic \: mass \: of \: carbon\: = 12u \: and \: oxyen \: = 16u)} \\ \blue{ \mathrm{Molecular \: Mass \: of \: \:CO_2 :\: \: 12 + 2(16)}} \\ \blue{ \mathrm{Molecular \: Mass \: of \:CO_2: \: \: 12 + 32 } } \\ \blue{ \boxed{ \mathrm{Molecular \: Mass \: of \: \: CO_2\: : \: \: \: 44u }}}$

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$\orange{\mathrm{{(v) \: To \: Calculate \: the \: Molecular \: Masses \: of: \: CH_4}} }\\ \\ \orange{\mathrm{Molecular \: Masses \: of \: \:CH_4 } }\ \\ \tiny\sf {(atomic \: mass \: of \: carbon\: = 12u \: and \: hydrogen\: = 1u)} \\ \orange{ \mathrm{Molecular \: Mass \: of \: \: CH_4:\: \: 12 + 4(1)}} \\ \orange{ \mathrm{Molecular \: Mass \: of \:CO_2: \: \: 12 + 4 } } \\ \orange{ \boxed{ \mathrm{Molecular \: Mass \: of \: \: CO_2\: : \: \: \: 16u }}}$

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$\red{\mathrm{{(vi) \: To \: Calculate \: the \: Molecular \: Masses \: of: \: C_2H_6 }} }\\ \\ \red{\mathrm{Molecular \: Masses \: of \: \ \: C_2H_6} }\ \\ \tiny\sf {(atomic \: mass \: of \: carbon\: = 12u \: and \: hydrogen\: = 1u)} \\ \red{ \mathrm{Molecular \: Mass \: of \: \: C_2H_6:\: \: 2(12) + 6(1)}} \\ \red{ \mathrm{Molecular \: Mass \: of \:CO_2: \: \: 24 + 6} } \\ \red{ \boxed{ \mathrm{Molecular \: Mass \: of \: \: CO_2\: : \: \: \: 30u }}}$

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$\color {darkblue}{\mathrm{{(vii) \: To \: Calculate \: the \: Molecular \: Masses \: of: C_2H_4\: }}}\\ \\ \color {darkblue}{{\mathrm{Molecular \: Masses \: of: C_2H_4\ \: } }}\ \\ \tiny\sf \pink{ {(atomic \: mass \: of \: carbon\: = 12u \: and \: hydrogen\: = 1u)}} \\ \color {darkblue}{{ \mathrm{Molecular \: Mass \: of \: \: C_2H_4:\: \: 2(12) + 4(1)}}} \\ \color {darkblue}{{ \mathrm{Molecular \: Mass \: of \:CO_2: \: \: 24 +4 } }} \\ \color {darkblue}{{ \boxed{ \mathrm{Molecular \: Mass \: of \: \: CO_2\: : \: \: \: 28u }}}}$

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$\color {teal}{\mathrm{{(vii) \: To \: Calculate \: the \: Molecular \: Masses \: of: NH_3\: }}}\\ \\ \color {teal}{{\mathrm{Molecular \: Masses \: of: NH_3\ \: } }}\ \\ \tiny\sf \pink{ {(atomic \: mass \: of \: nitrogen\: = 14u \: and \: hydrogen\: = 1u)}} \\ \color {teal}{{ \mathrm{Molecular \: Mass \: of \: \:NH_3:\: \: 14+ 3(1)}}} \\ \color {teal}{{ \mathrm{Molecular \: Mass \: of \:CO_2: \: \: 14 +3} }} \\ \color {teal}{{ \boxed{ \mathrm{Molecular \: Mass \: of \: \: CO_2\: : \: \: \: 17u }}}}$

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$\color {purple}{\mathrm{{(viii) \: To \: Calculate \: the \: Molecular \: Masses \: of: CH_3OH\: }}}\\ \\ \color {purple}{{\mathrm{Molecular \: Masses \: of: CH_3OH\ \: } }}\ \\ \tiny\sf \pink{ {(atomic \: mass \: of \: carbon\: = 12u \: oxygen = 16u\: and \: hydrogen\: = 1u)}} \\ \color {purple}{{ \mathrm{Molecular \: Mass \: of \: \:CH_3OH : \: \: 12+ 3(1) + 16 + 1}}} \\ \color {purple}{{ \mathrm{Molecular \: Mass \: of \:CO_2: \: \: 12 +3 + 17} }} \\ \color {purple}{{ \mathrm{Molecular \: Mass \: of \:CO_2: \: \: 12 +20} }}\\ \color {purple} {{ \boxed{ \mathrm{Molecular \: Mass \: of \: \: CO_2\: : \: \: \: 32u }}}}$

hope it helps you dear.. :)

have a good day :) ♡