The volume of 26.4 g carbon dioxide at r. t. p. is 14.6616 dm³.
The massof helium in the flask is0.0196 gram.

Explanation with steps

The problems can be solved with the ideal gas equation because it's low pressure at RTP (room temperature and pressure). This law is related to pressure, volume, temperature, and the molar amount of the gas. The ideal gas equation is given :

Where :

• P = pressure (atm).
• V = volume of the gas (L).
• n = the amount of gas (mole).
• R = the ideal gas constant
  R = 0.082 L atm / mole / K
• T = the temperature of the gas (K).

Number 24a

Given :

• m CO₂ = 26.4 g
• Ar C = 12 g/mol
  Ar O = 16 g/mol
• R.T.P or room temperature and pressure means :
  R = 0.082 L.atm/mole/K
  T = 25°C or 298 K
  P = 1 atm

Asked :

• The volume of CO₂ in dm³ = ?

Solution :

Step 1
Calculate Mr CO₂

• Mr CO₂ = Ar C + 2 x Ar O
  Mr CO₂ = 12 + 2 x 16
  Mr CO₂ = 44 g/mol

Step 2
Calculate mole of CO₂

• n CO₂ = m CO₂ : Mr CO₂
  n CO₂ = 26.4 g : 44 g/mol
  n CO₂ = 0.6 mole

Step 3
Calculate volume of CO₂

• P x V = n x R x T
  1 x V  = 0.6 x 0.082 x 298
  V       = 14.6616 L
  V       = 14.6616 dm³

Conclusion :

The volume of CO₂ is 14.6616 dm³.

Number 24b

Given :

• V He = 120 cm³
  V He = 0.12 dm³
  V He = 0.12 L
• Ar He = 4.0 g/mol
• R.T.P or room temperature and pressure means :
  R = 0.082 L.atm/mole/K
  T = 25°C or 298 K
  P = 1 atm

Asked :

• The mass of He in the flask = ?

Solution :

Step 1
Calculate mole of Helium gas

• P x V     = n x R x T
  1 x 0.12  = n x 0.082 x 298
  1 x 0.12  = n x 24.436
  n           = 0.12 : 24.436
  n           =  0.0049 moles.

Step 2
Calculate mass of Helium gas

Helium gas is He.

• m He = n He x Mr CO₂
  m He = 0.0049 moles x 4 g/mole
  m He = 0.0196 gram.

Conclusion :

The mass of helium gas is 0.0196 gram.

Learn more

• About other problems and solutions of the ideal gas law :
  yomemimo.com/tugas/4622903
  yomemimo.com/tugas/51464957
  yomemimo.com/tugas/51360973

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Details of solution

Class        : X
Subject    : Chemistry
Chapter   : Fundamental chemistry laws
Code        : 10.7.6