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25 Cards in this Set
- Front
- Back
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Gases deviate most from ideal behaviour at _____ pressure and ______ temperature. a. high; low b. low; high |
a |
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What is an ideal gas? |
A concept invented by scientists to approximate (model) the behaviour of real gases. |
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What are the two assumptions made when defining an ideal gas? |
1. The molecules themselves have no volume. 2. No forces exist between the molecules (except when the collide) |
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Under what conditions do real gases such as Hydrogen behave like ideal gases? |
Under normal conditions; around 100 kPa [approximately 1 atmosphere] pressure and 0ºC. |
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At a certain temperature an pressure, the _______ is proportional to the ________ of the gas. |
volume of a gas; number of moles. |
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What is Avogadro's law? |
Equal volumes of ideal gases measured at the same temperature and pressure contain the same number of molecules. Example: 100 cm3 of H2 contains the same number of molecules at 25ºC and 100 kPa as 100cm3 of NH3. (If we assume that they both behave as ideal gases. |
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What is STP and what is its value? |
Standard Temperature and Pressure. 273 K, 100 kPa (1 bar) |
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What is the molar volume of an ideal gas at STP? |
22.7 dm3mol-1 or 2,27 x 10^-2 m3mol-1 |
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What is molar volume? |
The volume occupied by one mole of a gas under certain conditions. Example: Under the same set of conditions, the volume occupied by one mole of NH3 is the same volume occupied by 1 mole of CO2 and one mole of H2 and this volume is 22.7 dm3 at STP. |
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What is the relationship between the number of moles in a gas and its volume? |
volume / molar volume |
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A change of 1ºC is the same as a change of ___ and 0ºC is equivalent to ____. |
1 K; 273 K |
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To convert ºC to K: ______ 273. To convert K to ºC: ______ 273. a. multiply; divide b.divide; multiply c. subtract; add d. add; subtract |
d |
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What is the formula for solving moles questions involving volumes of gases? |
m1 / (n1•M1) = V2 / (n2•Mv) m1= Mass of first substance (in g) n1= Coefficient of first substance M1= Molar mass of first substance V2 = Volume (in dm3) of second substance if it is a gas n2 = Coefficient of second substance Mv = Molar volume of a gas = 22.7 dm3 at STP |
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What is the alternative formula for solving moles questions involving volumes of gases is a volume is given and a volume is required? |
V1 / n1 = V2 / n2 V1= Volume of the first substance if it is a gas n1= Coefficient of first substance V2 = Volume of second substance n2 = Coefficient of second substance [V2 must have the same units as V1] |
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What is Boyle's law? |
At a constant temperature, the volume of a fixed mass of an ideal gas is inversely proportional to its pressure. |
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If the pressure of a gas is doubled at a constant temperature, then the volume will _________, and vice versa. a. double b. be halved c. stay the same. |
b |
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How is the relationship between pressure and volume illustrated? |
P ∝ 1/V P = k/V [k is a constant] or PV = k |
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The product of the pressure and volume of an ideal gas at a particular temperature is a constant and ________ as the pressure and volume change. a. does not change b. changes |
a |
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If the temperature is in Kelvin, what is the relationship between the volume and the temperature? |
The volume of a fixed mass of an ideal gas at constant pressure is directly proportional to its Kelvin temperature: V ∝ T ***This relationship does not work for temperatures in ºC. |
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If the Kelvin temperature is doubled and the pressure remains the same, then the volume will _________, and vice versa. a. double b. be halved c. stay the same. |
a ***The pressure will also double |
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Why can't an ideal gas ever liquify? |
Because there are no forces between the molecules. |
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What is the relationship between the pressure and the temperature? |
For a fixed mass of an ideal gas at constant volume, the pressure is directly proportional to its absolute temperature: P ∝ T |
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What is the overall gas law equation? |
(P1•V1) / T1 = (P2•V2) / T2 ***The temperature must be in Kelvin |
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What is the ideal gas equation? |
PV = nRT R = Gas constant n = Number of moles |
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What are the SI units for the gas equation? |
R = 8.31 JK-1 mol-1 Pressure: Nm-2 or Pa Volume: M3 Temperature: K |
