A radioactive metal atom decays (goes to another kind of atom) by emitting an alpha particle (He2+ ion). The alpha particles are collected as helium gas. A sample of helium with a volume of 10.25 mL was obtained at 771 mmHg and 23°C. How many atoms decayed during the period of the experiment?
This is a question off of my Chemistry WebAssign homework. I have tried everything and I still can't figure this question out. If you could tell me how to work the problem out I would really appreciate it. Thank you in advance.
This is a question off of my Chemistry WebAssign homework. I have tried everything and I still can't figure this question out. If you could tell me how to work the problem out I would really appreciate it. Thank you in advance.
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I read this as one He per decay
so if we get the number of He atoms, then we have the number of decayed atoms
so
P V = n R T
I'll use 62.4 L*mm/(mol*K) for R
P = 771 mm
V = 0.01025 L
T = 273+23 = 296 K
771(0.01025) = n (62.4) (296)
n = 4.279E-4 mol
and
4.279E-4 mol * 6.022E23 atom/mol = 2.577E20 decayed atoms
so if we get the number of He atoms, then we have the number of decayed atoms
so
P V = n R T
I'll use 62.4 L*mm/(mol*K) for R
P = 771 mm
V = 0.01025 L
T = 273+23 = 296 K
771(0.01025) = n (62.4) (296)
n = 4.279E-4 mol
and
4.279E-4 mol * 6.022E23 atom/mol = 2.577E20 decayed atoms