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### Topic: Few Chem Questions!  (Read 24142 times)

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#### nothincomin

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##### Few Chem Questions!
« on: May 20, 2010, 02:42:48 PM »

1) How many electrons would it take to the equal the mass of a proton?

2) A helium nucleus has two protons and two neutrons. How many electrons would it take to equal the mass of a helium nucleus?

#### sjb

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##### Re: Few Chem Questions!
« Reply #1 on: May 20, 2010, 04:00:56 PM »

1) How many electrons would it take to the equal the mass of a proton?

2) A helium nucleus has two protons and two neutrons. How many electrons would it take to equal the mass of a helium nucleus?

What is the mass of an electron? Of a proton? Of a neutron? What about binding energy?

#### nothincomin

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##### Re: Few Chem Questions!
« Reply #2 on: May 20, 2010, 10:35:05 PM »
Mass of Proton- 1.67262 X 10^-27
Mass of Electron 0.00091 X 10^-27

Mass of Proton/Mass of Electron
1.67262 X 10^-27/ 0.00091 X 10^-27= 1838.04 g
So therefore it would take 1838.04g of electrons to equal the mass of a proton. Let me know if I'm wrong.

#### AWK

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##### Re: Few Chem Questions!
« Reply #3 on: May 21, 2010, 01:18:31 AM »
Quote
So therefore it would take 1838.04g of electrons to equal the mass of a proton. Let me know if I'm wrong.
OK

Quote
1838.04 g
Should be without mass unit (g)
AWK

#### nothincomin

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##### Re: Few Chem Questions!
« Reply #4 on: May 21, 2010, 09:53:17 PM »

1) How many electrons would it take to the equal the mass of a proton?

2) A helium nucleus has two protons and two neutrons. How many electrons would it take to equal the mass of a helium nucleus?

For the 2nd question do I multiply 4 (protons + neutrons) X mass of electrons (0.00091 X 10^-27)?

#### Borek

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##### Re: Few Chem Questions!
« Reply #5 on: May 22, 2010, 04:57:50 AM »
For the 2nd question do I multiply 4 (protons + neutrons) X mass of electrons

Why multiply? What will be units of your answer if you multiply mass X mass?

If I will ask you how many apples weight the same as you would you multiply your weight with apple weight?
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#### nothincomin

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##### Re: Few Chem Questions!
« Reply #6 on: May 22, 2010, 12:25:05 PM »
So instead I would take mass of the helium nucleus/mass of an electron?

(2(1.67262 X 10^-27)) + (2(1.67493^10^-27))/ (0.00091 X10^-27)= 7357.25 electrons to equal the mass of the helium nucleus.
« Last Edit: May 22, 2010, 12:59:49 PM by nothincomin »

#### Borek

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##### Re: Few Chem Questions!
« Reply #7 on: May 22, 2010, 12:47:21 PM »
Close, and in general good approach, unfortunately final result is incorrect. Mass of helium nucleus is smaller than the sum of the masses of protons and neutrons, google "mass deficit".
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#### nothincomin

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##### Re: Few Chem Questions!
« Reply #8 on: May 22, 2010, 01:09:37 PM »
Were you referring to the the mass of a neutron? It was a typo, fixed it now.

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