6.2 Gases Avogadro’s Theory and Molar Volume

Law of Combining Volumes (Joseph Gay –Lussac ) When measured at the same temperature and pressure, volumes of gases react in simple whole number ratios. 2H 2 O(l)  2H 2 (g) + O 2 (g) (This reaction always produced twice as much hydrogen as oxygen)

Avogadro’s Theory Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.

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Fill in the table below ___C8H18(l) +___O2(g)  ___CO2(g )+ ___H2O(g) 2 mol 25 mol mol____mol 2 mol mol ____mol ___ L 25 L _____ L 18 L 8 L____L 64 L____L 5L____ L 250 mL_____mL ____mL

Fill in the table below ___C8H18(l) +____O2(g)  ___CO2(g )+ ___H2O(g) 2 mol 25 mol mol____mol 2 mol mol ____mol ___ L 25 L _____ L 18 L 8 L____L 64 L____L 5L____ L 250 mL_____mL ___ mL____mL

Fill in the table below ___C8H18(l) +__ O2(g)  ___CO2(g )+ ___H2O(g) 2 mol 25 mol mol____mol 2 mol mol ____mol ___ L 25 L _____ L 18 L 8 L____L 64 L____L 5L____ L 250 mL_____mL ____mL

Fill in the table below ___ C8H18(l) + ___O2(g)  ___CO2(g )+ __H2O(g) 2 mol 25 mol mol____mol 2 mol mol ____mol ___ L 25 L _____ L 18 L 8 L____L 64 L____L 5L____ L 250 mL_____mL ____mL

Fill in the table below 2 C8H18(l) + 25 O2(g)  18 H2O(g) + 16 CO2(g ) 2 mol 25 mol 18 mol 16 mol 4 mol 50 mol 36 mol 32mol 2 vol 25 vol 18 vol 16 vol 2 L 25 L 18 L 16 L 4L 50L 36 L 32 L 0.5L 6.25 L 4.5 L 4 L

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Molar Volume -The volume of one mole of any gas at a specific temperature and l/mol Remember STP is zero celsius and 101.3kPa And SATP(ambient) is 25 celsius and 100kPa

Calculations with molar volume n= v volume and n=m V molar volume M So v = m V M

Try this: Example 1: What volume is occupied by mol of nitrogen gas at STP?(ANS: 0.54 L) Example 2: How many moles of nitrogen dioxide are there in 75 L of the gas at SATP?(ANS: 3.02 mol)

Try this: Example 1: What volume is occupied by mol of nitrogen gas at STP?(ANS: 0.54 L) Example 2: How many moles of nitrogen dioxide are there in 75 L of the gas at SATP?(ANS: 3.02 mol)

Try this: Example 1: What volume is occupied by mol of nitrogen gas at STP?(ANS: 0.54 L) Example 2: How many moles of nitrogen dioxide are there in 75 L of the gas at SATP?(ANS: 3.02 mol)

#1 Answer n= v mol = __v___ V 22.4 L/mol 0.54 L = v

#2 Answer n= v n= 75 L V 24.8 L/mol n= 3.02 mol

volume mass mol particles concentration

Example #3 What volume of balloons does 7.00 g of helium gas fill at SATP? v=? m= 7.00 g M= 4.00 g/mol V= 24.8 L/mol (Ans 43.4 L)

Practise Questions: P L x 10 5 L x 10 5 L x 10 5 g 15a124 kL 15b250L 15c325L, 163L Remember to use ratios