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    (Original post by Nikitha13)
    First you need to balance the equation. So it would become
    2NaHCO3 -------> Na2CO3 + H2O + CO2
    You can just ignore the H2O and CO2 as they are only asking for the percentage yield of the NA2CO3

    You need to get the RFM of the reactant and the useful product.

    RFM of 2NaHCO3= 168

    RFM of Na2CO2= 106

    So 168g of 2NaHCO3 produces 106g of 2NaHCO3

    So 16.8 g makes 10.6g (divide by ten)

    So theoretical yield is 10.6g

    Percentage yield= (9.2/10.6)*100
    Answer= 86.8%
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    (Original post by samb1234)
    If you have Na2co3 and h2o there must have been 2 nahco3 in the first place, make sense?
    Yeah because it had a 2 before the NaHCO3>>> 2NaHCO3
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    (Original post by vickie89uk)
    Yep I've got that
    Ah ok, I wasn't sure if you had the 2 in your equation sorry, now you need to work out what the theoretical yield of your product is. What useful information can you gain from the balanced equation and how can you then use this to work out the theoretical yield?
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    (Original post by samb1234)
    Ah ok, I wasn't sure if you had the 2 in your equation sorry, now you need to work out what the theoretical yield of your product is. What useful information can you gain from the balanced equation and how can you then use this to work out the theoretical yield?
    Adding the mass numbers together Na2CO3 +H2O +CO2

    Again I'm not sure entirely.
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    (Original post by vickie89uk)
    Adding the mass numbers together Na2CO3 +H2O +CO2

    Again I'm not sure entirely.
    so in a theoretical world for every 2 moles of nahco3 we have reacting, we will produce 1 mole of naco3. Therefore if we can work out how many moles of nahco3 we had we can work out how many moles of na2co3 should be made
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    (Original post by Nikitha13)
    You can just ignore the H2O and CO2 as they are only asking for the percentage yield of the NA2CO3

    You need to get the RFM of the reactant and the useful product.

    RFM of 2NaHCO3= 168

    RFM of Na2CO2= 106
    Thank you what's FRM I'm have Ar Mr mass formula atomic mass etc
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    (Original post by samb1234)
    so in a theoretical world for every 2 moles of nahco3 we have reacting, we will produce 1 mole of naco3. Therefore if we can work out how many moles of nahco3 we had we can work out how many moles of naco3 should be made
    Ok so how do you even know that you get 1 mole for 2... Does that come with experience?!

    216g
    I don't know how I work that out either. My teacher doesn't recover a lesson if we miss one you have to teach yourself so I understand I probably seem really thick
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    (Original post by vickie89uk)
    Thank you what's FRM I'm have Ar Mr mass formula atomic mass etc
    RFM is the relative formula mass or the Mr (molecular mass) so u have to add the atomic mass of the elements

    RFM of 2NaHCO3= 168
    RFM of Na2CO2= 106
    So 168g of 2NaHCO3 produces 106g of 2NaHCO3
    So 16.8 g makes 10.6g (divide by ten)
    So theoretical yield is 10.6g
    Percentage yield= (9.2/10.6)*100Answer= 86.8%
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    (Original post by vickie89uk)
    Ok so how do you even know that you get 1 mole for 2... Does that come with experience?!

    216g
    I don't know how I work that out either. My teacher doesn't recover a lesson if we miss one you have to teach yourself so I understand I probably seem really thick
    the balanced symbol equation shows you with the big numbers in front
    2NaHCO3 → Na2CO3 + H2O + CO2

    there's a 2 in front of NaHCO3 but nothing (ie. a 1) in front of Na2CO3
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    (Original post by vickie89uk)
    Ok so how do you even know that you get 1 mole for 2... Does that come with experience?!

    216g
    I don't know how I work that out either. My teacher doesn't recover a lesson if we miss one you have to teach yourself so I understand I probably seem really thick
    Ok, I'll go into more detail and hopefully clear it up. The reason i know it's 2 is from the balanced chemical equation, so you will notice that the equation is 2NaHCO3 -> 1Na2HCO3 +h2o + co2 . This tells me that 2 moles of nahco3 react and become 1 mole of na2hco3, and some other stuff that isn't relevant to the question. Now I need to work out how many moles of NaHCO3 I have. The definition of a mole is that it's the amount of particles that there are in exactly 12g of carbon 12. What this essentially means is that 1 mole of an element would have the same mass in g as it's relative mass that appears on the periodic table. I then need to work out the RFM (relative formula mass) which is basically the total mass of the compound so I would add up the individual mass of the sodium, hydrogen etc. Therefore if one mole of my compound had a mass of say x, and I have Y grams of the compound, than the number of moles I have will be Y/x . Can you do it from there?
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    (Original post by Nikitha13)
    RFM is the relative formula mass or the Mr (molecular mass) so u have to add the atomic mass of the elements

    RFM of 2NaHCO3= 168
    RFM of Na2CO2= 106
    So 168g of 2NaHCO3 produces 106g of 2NaHCO3
    So 16.8 g makes 10.6g (divide by ten)
    So theoretical yield is 10.6g
    Percentage yield= (9.2/10.6)*100Answer= 86.8%
    Ok how did you add to 168 I got 216.... Thank you that makes sense

    (Original post by surina16)
    the balanced symbol equation shows you with the big numbers in front
    2NaHCO3 → Na2CO3 + H2O + CO2

    there's a 2 in front of NaHCO3 but nothing (ie. a 1) in front of Na2CO3
    So would it now just be NaHCO3 > NaCO3 + H2O + CO2
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    (Original post by vickie89uk)
    So would it now just be NaHCO3 > NaCO3 + H2O + CO2
    No, the equation remains the same, don't remove anything from the equation you balanced earlier
    If you want, I can show you my working out to this question but I believe you're not meant to on threads?
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    DON'T OPEN UNLESS YOU ARE COMPLETELY STUCK:
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    2NaHCO3 → Na2CO3 + H2O + CO2
    mass = Mr * moles
    moles = mass/Mr
    Mr of NaHCO3 = 84
    16.8 / 84 = 0.2
    0.2 moles of NAHCO3
    ratio of moles in the equation is 2:1
    0.2:0.1
    Mr of Na2CO3 = 106
    0.1/106 = 0.1
    0.1 moles Na2CO3
    10.6 g should be produced
    9.2/10.6 * 100 = 86.79245283018868
    = 86.8%
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    (Original post by vickie89uk)
    Ok how did you add to 168 I got 216.... Thank you that makes sense


    So would it now just be NaHCO3 > NaCO3 + H2O + CO2
    2 * (23+1+12+(16*3)) Hope that helps😃 You might have put your brackets in the wrong place.

    Sodium carbonate is Na2CO3
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    (Original post by samb1234)
    Ok, I'll go into more detail and hopefully clear it up. The reason i know it's 2 is from the balanced chemical equation, so you will notice that the equation is 2NaHCO3 -> 1Na2HCO3 +h2o + co2 . This tells me that 2 moles of nahco3 react and become 1 mole of na2hco3, and some other stuff that isn't relevant to the question. Now I need to work out how many moles of NaHCO3 I have. The definition of a mole is that it's the amount of particles that there are in exactly 12g of carbon 12. What this essentially means is that 1 mole of an element would have the same mass in g as it's relative mass that appears on the periodic table. I then need to work out the RFM (relative formula mass) which is basically the total mass of the compound so I would add up the individual mass of the sodium, hydrogen etc. Therefore if one mole of my compound had a mass of say x, and I have Y grams of the compound, than the number of moles I have will be Y/x . Can you do it from there?
    Na=23H=1C=12O= 4884g

    I still don't get it
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    (Original post by vickie89uk)
    Na=23H=1C=12O= 4884g

    I still don't get it
    Correct, so 1 mole of nahco3 has a mass of 84g, and we have 16.8g. So how many moles of nahco3 do we have
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    (Original post by surina16)
    DON'T OPEN UNLESS YOU ARE COMPLETELY STUCK:
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    2NaHCO3 → Na2CO3 + H2O + CO2
    mass = Mr * moles
    moles = mass/Mr
    Mr of NaHCO3 = 8416.8 / 84 = 0.2
    0.2 moles of NAHCO3
    ratio of moles in the equation is 2:1
    0.2:0.1
    Mr of Na2CO3 = 106
    0.1/106 = 0.1
    0.1 moles Na2CO3
    10.6 g should be produced
    9.2/10.6 * 100 = 86.79245283018868
    = 86.8%
    Spoiler:
    Show
    In future, although it is correct to do what you did, you're better off working out the raw number of moles (so use the actual RFM rather than saying the RFM of 2 moles, which isn't actually the RFM) and then using ratios, as you might need the raw number of moles for other parts of the question
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    (Original post by samb1234)
    Correct, so 1 mole of nahco3 has a mass of 84g, and we have 16.8g. So how many moles of nahco3 do we have
    5 moles

    74/16.8
    How does this get me to 86.9%

    I know I can do it it's just having someone explain it it's so infuriating that I am finding it so difficult

    Physics is my better subject it's simple triangles
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    (Original post by samb1234)
    Spoiler:
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    In future, although it is correct to do what you did, you're better off working out the raw number of moles (so use the actual RFM rather than saying the RFM of 2 moles, which isn't actually the RFM) and then using ratios, as you might need the raw number of moles for other parts of the question
    Thanks but I'm confused now aha - is 84 not the RFM?
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    (Original post by vickie89uk)
    5 moles

    74/16.8
    How does this get me to 86.9%

    I know I can do it it's just having someone explain it it's so infuriating that I am finding it so difficult

    Physics is my better subject it's simple triangles
    Otherway round, it's 16.8/84, don't worry about it everyone finds some stuff difficult. so now you know how many moles of nahco3 there are, you know by ratio that there are half the number of moles of na2co3. Then you just need to convert that back into a mass you can use
 
 
 
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