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Serhud [2]
3 years ago
10

The Half-Life of Pa-234 is 6.75 hours. How much (what fraction) of a sample of this isotope remains after 20.25 hours?

Chemistry
1 answer:
Grace [21]3 years ago
6 0
So in one hour half the amount remains (that's what half life means). In two hours 1/4 (or half of half) would remain and in three hours 1/8 would remain.
So the answer is 1/8
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How many grams of potassium chloride are needed to make 100 ml of a solution containing 250 mosmol/l? (m.w. of potassium is 39 a
LUCKY_DIMON [66]
In dilute solutions, the unit osmolarity is being used. It usually has units milliosmols per liter of solution or mOsmol/L. An osmole defines the number of moles of the solute that would have an effect on the osmotic pressure of the solution. Osmolarity is calculated by the product of the molarity and the number of particles in the solution which is 2 for potassium chloride. We calculate as follows:
Osmolarity = molarity (# of particles)250 mosmol/L ( 1 osmol / 1000 osmol) = x moles / .100 L (2)
x moles = 0.0125 mol KCl
mass KCl = 0.0125 mol KCl ( 39 + 35.5 g/mol) = 0.93125 g KCl
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Lapatulllka [165]

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Hey weirdo what's up?

So you got a question huh?

Lemme answer

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