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

A gas bottle is filled up with 200 gramms of hydrogen. Give the mass of oxygen filling for an identical bottle! (number only)

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

Fill in the Blanks

The density of a gas at 0°C and standtard pressure is 0.178 g/dm³. Answer by the name or xxx if not possible!

Fill in the Blanks

The relative density of a gas (to hydrogen) is 14.5. Give its molar mass in SI unit! (Number only!)

Fill in the Blanks

The relative density of an elemental gas (to air) is 0.552. Answer by the name or xxx if not possible!

Homework

Identification of gases