Gases Flashcards

1
Q

Gas

A

A substance that has no well defined boundaries but DIFFUSES rapidly to fill any container it’s places in

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2
Q

How can temp be converted to a kelvin from Celsius?

A

By adding 273

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3
Q

What us the standard temp, I.e the freezing point of water?

A

273K

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4
Q

Boyle’s Law

A

At constant temp. the volume of a fixed mass of gas is inversely proportional to its pressure

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5
Q

Charles’ Law

A

At constant pressure, the volume of a fixed mass of gas is directly proportional to its temp, measured on the Kelvin scale

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6
Q

Gay-Lussac’s Law of Combining Volumes

A

In a reaction between gases, the volumes of the reacting gases and the volumes of any gaseous products are in the ratio of small whole numbers, provided the volumes are measured at the same temp and pressure

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7
Q

Avogadro’s Law

A

Equal volumes of gases contain equal numbers of molecules under the same conditions of temp and pressure

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8
Q

An ideal gas

A

A gas that perfectly obeys all the assumptions of the kinetic theory of gases under all conditions of temp and pressure

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9
Q

How do Real gases differ from Ideal gases?

A
  • Forces of attraction and repulsion do exist between the molecules
  • the volume of the molecules isn’t negligible
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10
Q

When subbing into the equation PV=nRT

What are the units of pressure, volume and temperature?

A
Pressure= pascals
Volume= cubic metres 
Temperature= Kelvins
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11
Q

What is the equation of state for an ideal gas?

A

pV=nRT

-this tells us how the 4 variables change (V,P,T,n) going from one set of conditions to another

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12
Q

What is the pressure of a gas?

A

The pressure is the force that a gas exerts on a unit area of its container, measured in pascal (Pa)

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13
Q

What is a volatile liquid?

A

A liquid that has a low boiling point, and evaporates easily

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14
Q

Diffusion

A

The spreading of gases, e.g. smoke spreading around a room

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15
Q

Define matter

A

A scientific term for substances/materials

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16
Q

What are the three states of matter?

A

Solids, liquids, gases

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17
Q

What differentiates a gas from a solid or liquid?

A

Gas particles have more freedom of movement and will fill any container it’s placed in, they don’t have a fixed volume

18
Q

What are the particles of solids, liquids and gases?

A

Atoms, molecules or ions

19
Q

What two factors does the volume of a sample of gas depend on?

A

Temp. and pressure

20
Q

What is temperature?

A

A measure of the degree of hotness of an object (e.g. Celcius scale & Kelvin scale)

21
Q

What are the two fixed points of the Celsius scale?

A

Freezing point of water: 0 degrees

Boiling point of water: 100 degrees

22
Q

What temperature scale is also known as the absolute scale?

A

Kelvin scale (absolute zero -273 degrees Celsius)

23
Q

What is the volume of a gas?

A

Vol. of a sample of gas is the same as the vol. of the container it’s held in

24
Q

Why do we normally measure volume in cubic centimetres or Litres instead of cubic metres?

A

Cubic metres are too large for lab work

25
Q

What is S.t.p.

A

To find the volume of a gas, the temp. and pressure must be known
Standard temp. 273K (0 degrees)
Standard pressure 100kPa

26
Q

In what ways can gases vary, when still obeying the same laws?

A

Some are flammable, coloured, or poisonous

27
Q

What are the 5 gas Laws?

A
  1. Boyle’s Law
  2. Charles’ Law
  3. The Combined Gas Law
  4. Gay-Lussac’s Law of Combining Volumes
  5. Avogadro’s Law
28
Q

What did Boyle discover when studying the properties of gases?

A

As the pressure increases, the volume decreased—> V inversely proportional to P

29
Q

Explain Boyle’s Law in relation to a container of gas

A

If the volume of the container is decreased, the molecules are moving in a smaller space and will collide with each other and the walls more often. Increased no. Of collisions= increase in pressure

30
Q

What relationship of gases did Charles study?

A

The relationship between the vol. and temp. of a fixed mass of gas at constant pressure

31
Q

What is the Combined Gas Law/General Gas Law useful for?

A

Converting the volume of a fixed mass of gas under one set of conditions of T & P to the volume of the gas under a different set of conditions

32
Q

What’s two things are important to remember when using The Combined Gas Law?

A
  1. Convert temp. To Kelvin scale (like Charles)

2. Units on either side of the equation must be consistent

33
Q

Who discovered hydrogen?

A

Henry Cavendish

34
Q

What did Gay-Lussac confirm when doing experiments in combining the volumes of gases?

A

When H reacts with O2, two volumes of H always react with one volume of O to form two volumes of steam

35
Q

Who provided an explanation for Gay-Lussac’s Law of Combining Volumes?

A

Avogadro, as Dalton accused GL of being wrong

36
Q

Why does 100cm3 of hydrogen react with 100cm3 of Chlorine?

A

There is the same number of molecules of H and Cl in each volume

=hydrogen chloride

37
Q

Why was Avogadro’s Theory not accepted for so long?

A

Dalton’s theory didn’t allow for the existence of molecules

38
Q

At s.t.p. One mole of any gas occupies a volume of…

A

22.4Litres

39
Q

What is Molar volume?

A

The volume occupied by one mole of any gas

40
Q

What is the molar volume at room temp. and pressure?

A

24.0Litres

41
Q

What are 2 assumptions of the Kinetic Theory?

A
  1. Gases are made up of particles that are in continuous rapid, random motion, colliding with each other and the container’s walls
  2. There are no attractive/repulsive forces between the molecules of a gas
42
Q

Name 2 limitations of The Kinetic Theory of Gases?

A
  1. All real gases do have tiny attractive/repulsive forces. Polar gas molecules have attractive intermolecular forces
  2. Its not fair to say that volumes of the molecules of a gas is always negligible compared to the space they occupy