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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
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

... and your ideas are?
Reply 2
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emi711000
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Original post by charco
... and your ideas are?

No idea
Reply 3
Avatar for Ðeggs
Ðeggs
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(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.
(edited 3 years ago)
Reply 4
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emi711000
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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?
Reply 5
Avatar for Ðeggs
Ðeggs
22
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.
(edited 3 years ago)
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)
Reply 7
Avatar for As.1997
As.1997
16
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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