the mass of 1 litre of oxygen =1.4g how many litres of oxygen is given up at the combustion of 21g of magnesiumwhich has an equivalent of 0,5 mols.
2007-12-14 08:05:53 · 2 answers · asked by jammal hines 1 in Science & Mathematics ➔ Chemistry
you should probably tell us the chemical formula ega.. MgX
2007-12-14 08:33:56 · answer #1 · answered by Anonymous · 0⤊ 0⤋
"Equivalent of 0.5 mols" simply means that 1 mol Mg reacts with 0.5 mol O2. This is what you would expect, since Mg is in Group II, so its oxide is MgO.
As always, when balancing amounts of different substances, you have to go by way of moles.
Convert 21 g Mg to moles. Multiply by 0.5 to get moles O2. Multiply that number by the formula mass of O2 to get g O2.
To finish up, use
g O2 x (1 L O2/1.4 g O2) = L O2
Notice that when you do these unit conversions, the units have to cancel out to give you what you want. If you try to do it by commonsense, there is a good chance of your multiplying when you should be dividing.
2007-12-15 08:05:58 · answer #2 · answered by Facts Matter 7 · 0⤊ 0⤋