as chemistry 1 marker help x

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joke123132
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#1
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#1
which statement is correct about reactions involving halide ions?

a) sodium chloride forms chlorine when added to conc h2so4
b) sodium chloride forms chlorine when added to bromine
c)sodium bromide forms bromine when added to conc h2s04
d) sodium bromide forms bromine when added to iodine

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2) 5g of an oxide of molybdenum contains 4g of molybdenum

what is the empirical formula of this oxide?

a) MoO2
b) Mo405
C)Mo203
d)Mo3O2

a reply would be very appreciated! xx
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dxnixl
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#2
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#2
For Q1 - Remember that Chloride and Bromide ions can only be displaced by a more reactive element (so Fluorine and Chlorine/Fluorine respectively). This means that only one of a or c are correct. Not really sure on which one? 🤔

For Q2- If 5g of an oxide of Mo has 4g of Mo, it must have 1g of O.

So now work out empirical formula by calculating the molar ratio from this information (i’ve shown you how to work out the moles too):
4g Mo : 1g O
mol Mo : mol Mr
4g / Mr(Mo) : 1g / Mr(O)
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Pyruvic Acid
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#3
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#3
(Original post by joke123132)
which statement is correct about reactions involving halide ions?

a) sodium chloride forms chlorine when added to conc h2so4
b) sodium chloride forms chlorine when added to bromine
c)sodium bromide forms bromine when added to conc h2s04
d) sodium bromide forms bromine when added to iodine

------------------------------------------------------------------------------------------------------

2) 5g of an oxide of molybdenum contains 4g of molybdenum

what is the empirical formula of this oxide?

a) MoO2
b) Mo405
C)Mo203
d)Mo3O2

a reply would be very appreciated! xx
1. We know that B and D are incorrect - less reactive halogens do not displace more reactive halogens. We know that HCl is produced in A, not Cl2. This means that C is the correct answer.

2. We find that of the 5g of the oxide, 4g is made up of the Mo and 1g is made up of the O.
n = m/Mr; moles of O in 1g = 1/16
n = m/Mr; moles of Mo in 4g = 4/96 = 1/24

this means that the ratio of Mo to O = 1/24: 1/16
If we divide both numbers by the smallest number (i.e. divide by 1/24), we get 1:1.5
If we multiply both numbers by 2, we get a slightly cleaner ratio of 2:3
This means that C is the correct answer

Edit: I hopethat's right! Feel free to correct me if I'm wrong!
Last edited by Pyruvic Acid; 1 year ago
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joke123132
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#4
Report Thread starter 1 year ago
#4
(Original post by KaziMahathir)
1. We know that B and D are incorrect - less reactive halogens do not displace more reactive halogens. We know that HCl is produced in A, not Cl2. This means that C is the correct answer.

2. We find that of the 5g of the oxide, 4g is made up of the Mo and 1g is made up of the O.
n = m/Mr; moles of O in 1g = 1/16
n = m/Mr; moles of Mo in 4g = 4/96 = 1/24

this means that the ratio of Mo to O = 1/24: 1/16
If we divide both numbers by the smallest number (i.e. divide by 1/24), we get 1:1.5
If we multiply both numbers by 2, we get a slightly cleaner ratio of 2:3
This means that C is the correct answer

Edit: I hope that's right! Feel free to correct me if I'm wrong!
tysmmm
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