Iodine-131 is a radioactive isotope. after 9.00 days, 46.0% of a sample of 131i remains. what is the half-life of 131i?

1 answer:

6 0

For this problem, we use the integrated rate law for first order radioactive decay which is expressed as follows:<span>

An = Aoe^-kt

where An is the amount left after time t, Ao is the initial amount and k is a constant.

We need to calculate first the value of k from the given ration An/Ao and the time it reached that ration. We do as follows:

An = Aoe^-kt
0.46= e^-k(9)
k = 0.0863 / day

At half life, the remaining substance would be equal to one-half of the original so that An/Ao would be equal to 1/2 or 0.50. We calculate the half-life as follows:</span>

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the question you are looking for is

A compound containing only sulfur and nitrogen is 69.6% S by mass; the molar mass is 184 g/mol. What are the empirical and molecular formulas of the compound?

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1 year ago

Why is the combined cycle power generation system so much more efficient that the straight steam cycle?

rewona [7]

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Because it uses the residual energy of the fluid used by the first engine.

Explanation:

A combined cycle power generation counts with two heat engines that work in tandem from the same source of heat. The engines turn the energy into mechanical energy.

The cycle is much more efficient than the other, almost 60% more.

I hope this answer helps you.

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3 years ago

Dalton assumed that all atoms of the same element were identical in all their properties. Explain why this assumption is not val

jeka57 [31]

This assumption is not valid because, there are some elements which exist in two or more forms; they have the same atomic number but differ in their mass number, which meas that they possess different number of neutrons. These type of element are called isotopes. Isotope have the same atomic number and similar physical and chemical properties but they have different number of neutrons and therefore possess different masses.

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3 years ago

A 20.00 ml sample of a solution of sr(oh)2 is titrated to the equivalence point with 40.03 ml of 0.1159 n hcl. what is the molar

goblinko [34]

The molarity of Sr(OH)2 solution is = 0.1159 M

calculation
write the equation for reaction
that is, Sr(OH)2 +2HCl→ SrCl2 + 2 H2O

then finds the mole of HCl used

moles = molarity x volume
=40.03 x0.1159 = 4.639 moles

by use of mole ratio between Sr(OH)2 to HCL which is 1 :2 the moles of Sr(OH)2 is therefore = 4.639 x1/2 = 2.312 moles

molarity of Sr(OH)2 is = moles / volume

=2.312 /20 =0.1159 M

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