Elemental gases

Elemental gases

Make sure to have notes for next year!

Gases

• one of the four fundamental states of matter

• A pure gas may be made up of individual atoms , elemental molecules or compound molecules

• A gas mixture, such as air, contains a variety of pure gases.

• the vast separation of the individual gas particles.

• The interaction of gas particles considered negligible

Elemental gases

• The only chemical elements that are stable diatomic homonuclear molecules at 25°C and standrard pressure are H₂, N₂, O₂, and two halogens: F₂ and Cl₂.

• When grouped together with the monatomic noble gases – He, Ne, Ar, Kr, Xe and Rn

• – these gases are called "elemental gases".

Prior Knowledge - Inorganic Chemistry

• structure, polarity, secondary bonding, lattice system

• solubility in i) water & ii) other relevant solvents

• acid-base character

• redox behaviour

• manufacture

• "chemistry"

Prior Knowledge - Inorganic Chemistry/ Physical Chemistry

• ideal gases - real gases (models)

• Avogadro Law and molar volumes (0°C/ 20°C/ 25°C and standard pressure)

• empirical gas laws

• state equation of ideal gases: pV=nRT

• velocity equation and diffusion: Graham's Law

Gas mixtures

•  $M_1<\overline{M}<M_2$  

•  $\overline{M}=x_1\cdot M_1+x_2\cdot M_2$  ahol  $x_1+x_2=1$  

• Számoláshoz használt alakban!

•  $\overline{M}=x_1\cdot M_1+\left(1-x_1\right)\cdot M_2$  

•  $\overline{M}=x_1\cdot M_1+x_2\cdot M_2+...+x_n\cdot M_n$  

•  $\overline{M}=\sum_{i=1}^nx_i\cdot M_i$  feltéve  $\sum_{i=1}^nx_i=1$  

Density of gases

• relative density: d=M₁/M₂

• absolute density for "notable states" : ρ=M/V_m

• absolute density from pV=nRT

• V_m(25°C, standard p)=24,5 dm³/mol

• V_m(20°C, standard p)=24,0 dm³/mol

• V_m(0°C, standard p)=22,41 dm³/mol

Multiple Select

Which of the gases have significant solubility in water?

• chlorine

• hydrogen

• neon

• oxygen

• xenon

Multiple Choice

How many elemental gases are coloured?

• 0

• 1

• 2

• 3

• 4

Open Ended

Name a colourless gas "linked to colours" !

Fill in the Blanks

Multiple Choice

Give the mass of 6L hydrogen gas at 20°C and standrard pressure.

• 0.24 g

• 0.25 g

• 0.49 g

• 0.50 g

• 0.60 g

Homework

Identification of gases