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UNIT 2: REVIEW TIER 3. Apply Avogradro’s law to calculate reacting volumes of gases Apply the concept of molar volume at standard temperature and pressure in calculations Relate graphs to changes in temperature, pressure and volume according to the ideal gas equation.
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UNIT 2: REVIEWTIER 3 • Apply Avogradro’s law to calculate reacting volumes of gases • Apply the concept of molar volume at standard temperature and pressure in calculations • Relate graphs to changes in temperature, pressure and volume according to the ideal gas equation
According to Avogadro’s hypothesis, equal volumes of different gases contain equal numbers of particles at the same temperature and pressure
ACCORDING TO AVOGRADRO’S HYPOTHESIS THE VOLUME OF CARBON MONOXIDE WOULD BE TWICE THE VOLUME OF OXYGEN GAS IN THE REACTION BELOW. THIS REACTION WOULD THEORETICALLY PRODUCE THE SAME VOLUME OF CARBON DIOXIDE AS THE CARBON MONOXIDE REACTED 2CO(g) + O2(g) 2CO2(g) THE COEFFICIENTS CAN BE USED AS RATIOS TO DETERMINE VOLUME THE SAME WAY THEY ARE USED TO DETERMINE MOLES.
IF 10 dm3 of CO is reacted how many dm3 of O2 is reacted 2CO(g) + O2(g) 2CO2(g) Set up the ratio: 10dm3 CO = xdm3 O2 2 1 X = 5 dm3
Apply the concept of molar volume at standard temperature and pressure in calculations STANDARD TEMPERATURE & STANDARD PRESSURE IS REFERRED TO AS STP STANDARD TEMPERATURE IS 0oC OR 273K STANDARD PRESSURE IS 1 atm = 760 mmHg = 760 torr = 101.325 kPa = 101,325 Pa ONE MOLE OF ANY GAS AT STP OCCUPIES 22.4 LITERS OR 22.4 dm3 or 22.4 dm-3
PROBLEM: If you had 2.5 moles of nitrogen in the equation below, how much(dm3) ammonia could you theoretically produce at STP? N2 +3 H22 NH3 2.5moles N2 = x x= 5moles NH3 1 2 5 moles NH3 x 22.4 dm3= 112dm3 1 mol HOW MUCH (dm3 )HYDROGEN WOULD BE NEEDED TO REACT ALL THE NITROGEN? 2.5moles N2 = x x= 7.5moles H2 1 3 7.5 X 22.4 = ANSWER: 168 dm3
THE PRESSURE OF A GAS IS INVERSELY PROPORTIONAL TO THE VOLUME. AS THE VOLUME DECRESES THE PRESSURE INCREASES V1P1 = V2 P2 A GRAPH OF P AGAINST 1/V PRODUCES A STRAIGHT LINE THROUGH THE ORIGIN
THE PRESSURE IS PROPORTIONAL TO THE ABSOLUTE TEMPERATURE. THE PRESSURE OF THE GAS IS ZERO AT ABSOLUTE ZERO WHEN THE PARTICLES ARE NOT MOVING (-273oC) P1 = P2 T1 T2 T must be in Kelvin K = oC + 273
VOLUME IS PROPORTIONAL TO THE ABSOLUTE TEMPERATURE V1= V2 T1 T2 T must be in Kelvin K = oC + 273