Question

Calculate the mass of 0.5 mole of N2 (Nitrogen gas). ( atomic mass of N =14u) 3. Calculate the Molar mass of HCl. (atomic mass of H =1u; Cl = 35.5u) 4. Calculate the number of moles in 48g of helium (atomic mass of He= 4u ) 5. Calculate the Molar Mass of C2H6. (atomic mass of H =1u; and C=12u)

Answer 1

1) no. of mole of N2 = 0.5

atomic mass of N = 14 u

molar mass of N2 = 14×2 = 28 g mol^-1

given mass = morar mass × no . of moles

= 28 × 0.5 = 14 g

2) molar mass of HCl = (molar mass of H) + (molar mass of Cl )

= 1 + 35.5 = 36.5 g mol^-1

3) molar mass of He = 4  g mol^-1

given mass  = 48g

no. of moles = given mass / molar mass = 48 / 4 = 12 mol

4) molar mass of C2H6 = 2(molar mass of C)+ 6(molar mass of H)  

2 × 6 + 6 × 1

12 + 6 = 18 g mol^-1

Answer 2

To find:

• The mass of 0.5 mole of N2

• The Molar mass of HCl

• The number of moles in 48g of helium

• The Molar Mass of C2H6.

Calculation:

1st part:

1 mole of $N_{2}$ weighs (14×2) = 28 g.

=> 0.5 moles of $N_{2}$ weighs 14 g.

2nd part:

Molar mass of HCl

$\rm{= mass \: of \: H + mass \: of \: Cl}$

$\rm{ = 1 + 35.5}$

$\rm{ = 36.5 \: g {mol}^{ - 1} }$

3rd part:

Number of moles in 48 g Helium ;

$\sf{no. \: of \: moles = \dfrac{given \: mass}{molar \: mass} }$

$\sf{ = > no. \: of \: moles = \dfrac{48}{4} }$

$\sf{ = > no. \: of \: moles = 12 \: mol}$

4th part:

Molar mass of C2H6 ;

$\rm{ = 2 \times (mass \: of \: C) + 6 \times (mass \: of \: H)}$

$\rm{ = 2 \times (12) + 6 \times (1)}$

$\rm{ = 24 + 6}$

$\rm{ = 30 \: g {mol}^{ - 1} }$

Hope It Helps.