EffKayy
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3 The human body contains around 0.025 g of iodine molecules, I2. Which of the
following shows the number of iodine atoms in 0.025 g of I2?
The Avogadro constant is 6.02 × 1023 mol–1.
A 0 025
---------
126 9 x. 6 02 1023
.
× . ×
B 0 025
---------
253 8 x. 6 02 1023
.
× . ×
C 253 8
-----------
0 025 x. 6 02 1023
.
× . ×
D 126 9
-------
0 025 x6 02 1023

The answer is A but im not sure why because i thought it was B. i thought it was B because if its Iodine, and its I2, surely you do 126.9 x 2? :| Help.
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charco
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(Original post by EffKayy)
3 The human body contains around 0.025 g of iodine molecules, I2. Which of the
following shows the number of iodine atoms in 0.025 g of I2?
The Avogadro constant is 6.02 × 1023 mol–1.
A 0 025
---------
126 9 x. 6 02 1023
.
× . ×
B 0 025
---------
253 8 x. 6 02 1023
.
× . ×
C 253 8
-----------
0 025 x. 6 02 1023
.
× . ×
D 126 9
-------
0 025 x6 02 1023

The answer is A but im not sure why because i thought it was B. i thought it was B because if its Iodine, and its I2, surely you do 126.9 x 2? :| Help.
yeah, but the question asks you for iodine ATOMS
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Maker
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I think you are getting mass and volume mixed up. The number of atoms in 126.9g of iodine is 6.02 x 1023.

The number of atoms in 0.025g is 0.025/126.9 x 6.02 x 1023

Molecular mass is only relevant when its a gas and you are using its volume to determine number of moles or molecular weight.
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azrah vakil
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(Original post by Maker)
I think you are getting mass and volume mixed up. The number of atoms in 126.9g of iodine is 6.02 x 1023.

The number of atoms in 0.025g is 0.025/126.9 x 6.02 x 1023

Molecular mass is only relevant when its a gas and you are using its volume to determine number of moles or molecular weight.
sorry but i didnt understand
can u explain this again!
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bleak_rage
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Hi!

If you think a bit, you'll realize that the mass of iodine molecules is the same as the mass of iodine atoms. Since they are asking for number of atoms you're answer should be A, i.e. moles of iodine atoms x Avogradro constant.

Hope it helped!
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username3110466
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Im sure he needed the help 7 years later.....
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bleak_rage
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(Original post by theoneandonlybob)
Im sure he needed the help 7 years later.....
LOL just realized this post was 7 years old...
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