maybe one of them is MCl and the other is MCl2
a mol of Cl is about 35.5 grams
so when we added a Cl to the molecule, the mass went up by (16.5 - 12.7) =3.8 grams which is 3.8/35.5 = 0.107 mols of Cl
so we must have had 0.107 mols of M in the MCl
3.8 grams of the original MCl was Cl so
12.7 - 3.8 = 8.9 grams of M is 0.107 mols of M
so molar mass of M is 8.9 g / 0.107 mols = 83.2 grams/mol
Looks like Pb, lead :)
PbCl and PbCl2 ????
A metal M forms 2 different chloride. if 12.7g of chloride A and 16.5g of chloride B show that the figures agree with the law of multiple proportion and write their formular
3 answers
I have a hunch that there is more given in the problem statement than you gave us. It could be MCl2 and MCl4 or whatever However that is the general idea.
I intended to let this go but since Damon made a stab at it I will be brave. Frankly, I don't know how to handle this because I can get any answer I want. Let's do an example where we know what M is.
100 g C combines with 133 g oxygen to form 233 g of an oxide.(It's CO)
100 g C combines with 266 g oxygen to form 366 g of a different oxide.(CO2)
The Law of Multiple Proportions says that for a fixed mass of an element (100 g C) then the ratio of the oxygen to form the two compounds will be in the ratio of small whole numbers (and they are because 266/133 = 2:1.
BUT suppose we don't know the identity of M AND we don't know the mass of M. All we know is MClx = 12.7 g and MCly = 16.5 g. We can assume M = a mass of say 5 g, then 12.7-5 = 7.7 for mass Cl in A and 16.5-5 = 11.5 g Cl in B. 11.5/7.7 = 1.5. Yea!! That's a ratio of 2:3 and yes small whole numbers. BUT, what if we pick another constant number for M, say 10 g?
Then 12.7-10 = 2.7 and 16.5 - 10 = 6.5 and 6.5/2.7 = 2.4 which, with some stretching to allow for "experimental error" the ratio is 2:5. Suppose we pick 1 for M, then 12.7 - 1 =11.7 and 16.5-1 = 15.5 and the ratio is 1:1.32 for a ratio of 3:4. All of these give small whole numbers but they aren't consistent. Therefore,
I think we might say it obeys the Law of M P but I don't think I could write an equation for it.
100 g C combines with 133 g oxygen to form 233 g of an oxide.(It's CO)
100 g C combines with 266 g oxygen to form 366 g of a different oxide.(CO2)
The Law of Multiple Proportions says that for a fixed mass of an element (100 g C) then the ratio of the oxygen to form the two compounds will be in the ratio of small whole numbers (and they are because 266/133 = 2:1.
BUT suppose we don't know the identity of M AND we don't know the mass of M. All we know is MClx = 12.7 g and MCly = 16.5 g. We can assume M = a mass of say 5 g, then 12.7-5 = 7.7 for mass Cl in A and 16.5-5 = 11.5 g Cl in B. 11.5/7.7 = 1.5. Yea!! That's a ratio of 2:3 and yes small whole numbers. BUT, what if we pick another constant number for M, say 10 g?
Then 12.7-10 = 2.7 and 16.5 - 10 = 6.5 and 6.5/2.7 = 2.4 which, with some stretching to allow for "experimental error" the ratio is 2:5. Suppose we pick 1 for M, then 12.7 - 1 =11.7 and 16.5-1 = 15.5 and the ratio is 1:1.32 for a ratio of 3:4. All of these give small whole numbers but they aren't consistent. Therefore,
I think we might say it obeys the Law of M P but I don't think I could write an equation for it.
0 answers