# Chemistry help

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#1
A sample of chromium contains four isotopes and has a relative atomic mass of 52.09
s the mass number and the percentage abundance of three of these isotopes.
Mass number 52 53 54
Abundance (%) 82.8, 10.9, 2.7
Determine the percentage abundance of the fourth isotope. Show by calculation that the mass number of this isotope is 50
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1 year ago
#2
(Original post by emi711000)
A sample of chromium contains four isotopes and has a relative atomic mass of 52.09
s the mass number and the percentage abundance of three of these isotopes.
Mass number 52 53 54
Abundance (%) 82.8, 10.9, 2.7
Determine the percentage abundance of the fourth isotope. Show by calculation that the mass number of this isotope is 50
0
#3
(Original post by charco)
No idea
0
1 year ago
#4
(0.828 x 52) (53 x 0.109) (0.027 x 54) (X x 50) = 52.09

Work out what x is by 1-0.828-0.109-0.027, then show that this decimal can be converted into a percentage.
Last edited by Ðeggs; 1 year ago
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#5
(Original post by Deggs_14)
(0.828 x 52) (53 x 0.109) (0.027 x 54) (X x 50) = 52.09

Work out what x is by 1-0.828-0.109-0.027, then show that this decimal can be converted into a percentage.
Where did you get the 1-0 from?
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1 year ago
#6
(Original post by emi711000)
Where did you get the 1-0 from?
You’re given percentage values as the abundance. Use (82.8 / 100) instead of 0.828 if you like, same thing. The abundance of the isotope of the Mr of 50 is all the percentage abundances subtracted by 100 %. Then prove that the mass number of the final isotope is 50 by calculation as I showed you above.
Last edited by Ðeggs; 1 year ago
0
1 year ago
#7
(Original post by emi711000)
A sample of chromium contains four isotopes and has a relative atomic mass of 52.09
s the mass number and the percentage abundance of three of these isotopes.
Mass number 52 53 54
Abundance (%) 82.8, 10.9, 2.7
Determine the percentage abundance of the fourth isotope. Show by calculation that the mass number of this isotope is 50
Relative atomic mass is the weighted average of all of the isotopes in a element.

If the abundance is 82.8% this means that in every 100 atoms 82.8 of them have a mass of 52 units.

So the RAM is the sum of masses of 100 typical atoms divided by 100.

In your question you have 4 isotopes each with difference masses and each has a different abundance.

You know the % abundance of the missing isotope and you know the final answer (the RAM)
0
1 year ago
#8
(Original post by emi711000)
A sample of chromium contains four isotopes and has a relative atomic mass of 52.09
s the mass number and the percentage abundance of three of these isotopes.
Mass number 52 53 54
Abundance (%) 82.8, 10.9, 2.7
Determine the percentage abundance of the fourth isotope. Show by calculation that the mass number of this isotope is 50
If you find the above confusing to understand. The best thing would be to look up the equation and put the values in. Then solve for x.
(I’m assuming your basic algebra is good)
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