Original post by _jess_here__
how do I approach this kinda question
Attachment not found
how do I approach this kinda question
"Attachement not found", try putting the qestion into text form so its possible / easy for people to see it as a starting point
.Original post by Mr Wednesday
"Attachement not found", try putting the qestion into text form so its possible / easy for people to see it as a starting point .
.ah sorry so the question was when 3.00g of an anhydrous nitrate of a group 2 metal is decomposed 1.53 g of gas is produced what is the nitrate compound ?
1.berilliyum nitrate
2. calcium nitrate
3. Magnesium nitrate
4. strontium nitrate
Original post by _jess_here__
ah sorry so the question was when 3.00g of an anhydrous nitrate of a group 2 metal is decomposed 1.53 g of gas is produced what is the nitrate compound ?
1.berilliyum nitrate
2. calcium nitrate
3. Magnesium nitrate
4. strontium nitrate
1.berilliyum nitrate
2. calcium nitrate
3. Magnesium nitrate
4. strontium nitrate
Ok, 1st part, write down structures for each of those compunds, e.g. Be (NO3)2 etc. 2nd part, work out atomic mass of the molecule - be creatively lazy here, only work out the mass of (NO3)2 once
. 3rd part, work out what fraction of a 3g mass of each compound is composed of nitrogen and oxygen.(edited 4 years ago)
Original post by Mr Wednesday
Ok, 1st part, write down structures for each of those compunds, e.g. Be (NO3)2 etc. 2nd part, work out atomic mass of the molecule - be creatively lazy here, only work out the mass of (NO3)2 once . 3rd part, work out what fraction of a 3g mass of each compound is composed of nitrogen.
. 3rd part, work out what fraction of a 3g mass of each compound is composed of nitrogen.But we don't know the RFM of M(NO3)2
Original post by _jess_here__
ah sorry so the question was when 3.00g of an anhydrous nitrate of a group 2 metal is decomposed 1.53 g of gas is produced what is the nitrate compound ?
1.berilliyum nitrate
2. calcium nitrate
3. Magnesium nitrate
4. strontium nitrate
1.berilliyum nitrate
2. calcium nitrate
3. Magnesium nitrate
4. strontium nitrate
which metal does it show in mark scheme?
Original post by lyer_in_hellfyre
But we don't know the RFM of M(NO3)2
You have a limited range of possibilities so start working from the top of the list down, and eliminate ones that are "impossible" until you find the unique one that fits.
Original post by Mr Wednesday
You have a limited range of possibilities so start working from the top of the list down, and eliminate ones that are "impossible" until you find the unique one that fits.
But how do we do that without knowing its moles? Do we take 1 because the stoichiometric equation says so?
Original post by Mr Wednesday
3rd part, work out what fraction of a 3g mass of each compound is composed of nitrogen.
Also i didnt get this... sorry and
for your time...what metal did you get? im getting as Sr
This is the method i used :
If 2.5 moles of total gases have 108g according to molar mass and balanced equation,
1.53g of total gases gives me...3.54E-2 moles of total gas formed.
If the ratio of metal oxide: total gases is 1 is to 2.5, after plugging the moles found frm above i get 1.41E-2 moles of metal oxide. I do know the mass of metal oxide (subtract mass of gases formed from 3g )
So now with moles and mass, i could find rfm of metal after subtracting molar mass of oxygen.
(edited 4 years ago)
Original post by lyer_in_hellfyre
which metal does it show in mark scheme?
A
Original post by lyer_in_hellfyre
which metal does it show in mark scheme?
berillium
Original post by _jess_here__
berillium
yikes how come :/
Original post by lyer_in_hellfyre
yikes how come :/
uhh idek tis sucks
The thermal decomposition of a group 2 nitrate would decompose according to:
M(NO3)2 (s) —-> MO (s) + 4NO2 (g) + O2 (g). This is the first thing you should write.
Then I would work out (1.53/3.00) x 100 = 51%. So 51% gas is produced by mass.
Then work out the atom economy of the general decomposition formula using each group 2 ion, and see which group 2 metal.
The Mr of Sr(NO3)2 is 211.6 and the Mr of 4NO2 + O2 = 216. So these Mr values will make the 49/51% Mr ratio we’re interested in.
Hence the answer is Strontium.
The most common way to answer the question is just simply trial and error, there are only several group 2 metals, so just substitute their different Mr values until you find the one that works.
M(NO3)2 (s) —-> MO (s) + 4NO2 (g) + O2 (g). This is the first thing you should write.
Then I would work out (1.53/3.00) x 100 = 51%. So 51% gas is produced by mass.
Then work out the atom economy of the general decomposition formula using each group 2 ion, and see which group 2 metal.
The Mr of Sr(NO3)2 is 211.6 and the Mr of 4NO2 + O2 = 216. So these Mr values will make the 49/51% Mr ratio we’re interested in.
Hence the answer is Strontium.
The most common way to answer the question is just simply trial and error, there are only several group 2 metals, so just substitute their different Mr values until you find the one that works.
(edited 4 years ago)
Original post by Deggs_14
The thermal decomposition of a group 2 nitrate would decompose according to:
M(NO3)2 (s) —-> MO (s) + 4NO2 (g) + O2 (g). This is the first thing you should write.
Then I would work out (1.53/3.00) x 100 = 51%. So 51% gas is produced by mass.
Then work out the atom economy of the general decomposition formula using each group 2 ion, and see which group 2 metal.
The Mr of Sr(NO3)2 is 211.6 and the Mr of 4NO2 + O2 = 216. So these Mr values will make the 49/51% Mr ratio we’re interested in.
Hence the answer is Strontium.
The most common way to answer the question is just simply trial and error, there are only several group 2 metals, so just substitute their different Mr values until you find the one that works.
M(NO3)2 (s) —-> MO (s) + 4NO2 (g) + O2 (g). This is the first thing you should write.
Then I would work out (1.53/3.00) x 100 = 51%. So 51% gas is produced by mass.
Then work out the atom economy of the general decomposition formula using each group 2 ion, and see which group 2 metal.
The Mr of Sr(NO3)2 is 211.6 and the Mr of 4NO2 + O2 = 216. So these Mr values will make the 49/51% Mr ratio we’re interested in.
Hence the answer is Strontium.
The most common way to answer the question is just simply trial and error, there are only several group 2 metals, so just substitute their different Mr values until you find the one that works.
for reconfirming and detailed explanation!Original post by _jess_here__
uhh idek tis sucks
The answer frm mark scheme is wrong :/
(edited 4 years ago)
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