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snow_tiger [21]
3 years ago
10

Iodine-131 is administered orally in the form of NaI(aq) as a treatment for thyroid cancer. The half-life of iodine-131 is 8.04

days. If you begin with 34.7 mg of this isotope, what mass remains after 8.52 days have passed
Chemistry
1 answer:
evablogger [386]3 years ago
8 0

Answer:

16.6 mg

Explanation:

Step 1: Calculate the rate constant (k) for Iodine-131 decay

We know the half-life is t1/2 = 8.04 day. We can calculate the rate constant using the following expression.

k = ln2 / t1/2 = ln2 / 8.04 day = 0.0862 day⁻¹

Step 2: Calculate the mass of iodine after 8.52 days

Iodine-131 decays following first-order kinetics. Given the initial mass (I₀ = 34.7 mg) and the time elapsed (t = 8.52 day), we can calculate the mass of iodine-131 using the following expression.

ln I = ln I₀ - k × t

ln I = ln 34.7 - 0.0862 day⁻¹ × 8.52 day

I = 16.6 mg

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The bomb calorimeter in Exercise 102 is filled with 987g water. The initial temperature of the calorimeter contents is 23.32. A
Sholpan [36]

Answer:

25.907°C

Explanation:

In Exercise 102, heat capacity of bomb calorimeter is 6.660 kJ/°C

The heat of combustion of benzoic acid is equivalent to the total heat energy released to the bomb calorimeter and water in the calorimeter.

Thus:

-q_{combust} = q_{water} + q_{calori}

q_{combust} = heat of combustion of benzoic acid

q_{water} = heat energy released to water

q_{calori} = heat energy released to the calorimeter

Therefore,

-m_{combust}*H_{combust} = [m_{water}*c_{water} + C_{calori}]*(T_{f} - T_{i})

1.056*26.42 = [0.987*4.18 + 6.66](T_{f} - 23.32)

27.8995 = [4.12566+6.660](T_{f} - 23.32)

(T_{f} - 23.32) = 27.8995/10.7857 = 2.587

T_{f} = 23.32 + 2.587 = 25.907°C

4 0
3 years ago
What is the number of atoms in 3.75 mol fe
Kruka [31]
1mol=6.022x10^23 atoms
3.75mol= 6.022x3.75x10^23 atoms
             =2.2583x10^24 atoms
8 0
3 years ago
The energy of a pendulum is recorded at different positions in the table below. Use the data in the table to determine the amoun
natta225 [31]

Answer:

36.55 J

Explanation:

PE = Potential energy

KE = Kinetic energy

TE = Total energy

The following data were obtained from the question:

Position >> PE >>>>> KE >>>>>> TE

1 >>>>>>>> 72.26 >> 27.74 >>>> 100

2 >>>>>>>> 63.45 >> x >>>>>>>> 100

3 >>>>>>>> 58.09 >> 41.91 >>>>> 100

The kinetic energy of the pendulum at position 2 can be obtained as follow:

From the table above, at position 2,

Potential energy (PE) = 63.45 J

Kinetic energy (KE) = unknown = x

Total energy (TE) = 100 J

TE = PE + KE

100 = 63.45 + x

Collect like terms

100 – 63.45 = x

x = 36.55 J

Thus, the kinetic energy of the pendulum at position 2 is 36.55 J.

7 0
2 years ago
Which process requires water to gain heat energy from the environment
elixir [45]

Answer:

Evaporation

Explanation:

Evaporation is the certain process that requires water to gain heat energy from the environment.

4 0
3 years ago
The noble gases are the least
cricket20 [7]

Answer:

reactive nonmetals since they have a full valence shell (that's why they're stable).

4 0
3 years ago
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