Question

Bismuth-210 is beta emitter with a half-life of 5.0 days.

Part A

If a sample contains 1.3 g of Bi-210 (atomic mass = 209.984105 amu), how many beta emissions occur in 14.0 days? Express your answer using two significant figures. betadecays

Part B

If a person's body intercepts 5.5 % of those emissions, to what dose of radiation (in Ci) is the person exposed? Express your answer using two significant figures. Dose of radiation = Ci

Answer #1

**Moles of Bi = mass of Bi / atomic mass of Bi = 1.3
/209.984105 = 0.006191**

**Number of Bi atoms = 6.023 x 10^23 x moles = 6.023x10^23
x0.006191 = 3.7288 x 10^21**

**half life= 5 days**

**k = 0.693/ t1/2 = 0.693/5 =
0.13863 is decay constant**

**now t = 14 , we have formula t = ( 1/k) ln (
a/a-x)**

**where a= initial amount , a-x= final amount**

**14 = ( 0.13863) ln ( 3.7288 x 10^21 / a-x)**

**a-x = 0.5354 x10^21**

**Bi decayed = a-(-ax) = ( 3.7288-0.5354) x 10^21 = 3.2 x
10^21**

**Thus number of decays = 3.2 x 10^21**

**B) 5.5 % of emissions = ( 5.5/100) x 3.2 x 10^21 = 0.176
x 10^21**

**1 Ci = 3.7 x 10^10**

**hence dose in Ci = ( 0.176x10^21 /3.7x10^10) = 4.8 x
10^9**

Bi−210 is a beta emitter with a half-life of 5.0 days. Part A If
a sample contains 1.8 g of Bi−210 , how many beta emissions would
occur in 10 days?

A patient ingests 140 mg of 131I (iodine-131), a beta emitter
with a half-life of 8.0 days. Assuming that none of the 131I is
eliminated from the person's body in the first 4.0 hours of
treatment, what is the exposure (in Ci) during those 4.0 hours?
Express your answer using two significant figures.
exposure= _____ Ci

An 85 kg patient swallows a 30 μCi beta emitter with a half-life
of 5.0 days, and the radioactive nuclei are quickly distributed
throughout his body. The beta particles are emitted with an average
energy of 0.35 MeV, 90% of which is absorbed by the body.
What dose equivalent does the patient receive in the
first week?

The half-life of 235U, an alpha emitter, is 7.1×108 yr.
Part A
Calculate the number of alpha particles emitted by 3.4 mg of
this nuclide in 3 minutes.
Express your answer using two significant figures.

A particular saturated solution of PbI2 has [Pb2+]=5.0×10−3M and
[I−]=1.3×10−3M.
Part A
What is the value of Ksp for PbI2?
Express your answer using two significant figures.
Part B
What is [I−] in a saturated solution of PbI2 that has [Pb2+] =
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Express your answer using two significant figures.
Part C
What is [Pb2+] in a saturated solution that has [I−] =
2.4×10−4 M ?
Express your answer using two significant figures.

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