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kakasveta [241]
2 years ago
11

Iodine-131 is a beta emitter used as a tracer in radio immunoassays in biological systems. It follows first order kinetics. The

half-life if iodine-131 is 8.04 days. If you start with 8.0 grams of iodine-131, how many grams would remain at 39 days
Chemistry
1 answer:
allsm [11]2 years ago
3 0

<u>Answer:</u> The amount of Iodine-131 remain after 39 days is 0.278 grams

<u>Explanation:</u>

The equation used to calculate rate constant from given half life for first order kinetics:

t_{1/2}=\frac{0.693}{k}

where,

t_{1/2} = half life of the reaction = 8.04 days

Putting values in above equation, we get:

k=\frac{0.693}{8.04days}=0.0862days^{-1}

Rate law expression for first order kinetics is given by the equation:

k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}

where,

k = rate constant = 0.0862days^{-1}

t = time taken for decay process = 39 days

[A_o] = initial amount of the sample = 8.0 grams

[A] = amount left after decay process = ?

Putting values in above equation, we get:

0.0862=\frac{2.303}{39}\log\frac{8.0}{[A]}

[A]=0.278g

Hence, the amount of Iodine-131 remain after 39 days is 0.278 grams

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A sample of water is heated from 60.0 °C to 75.0°C by the addition of 140 j of
kupik [55]

Mass of the water : 2.23 g

<h3>Furter explanation</h3>

Heat

Q = m.c.Δt

m= mass, g

c = heat capacity, for water : 4.18 J/g° C.

ΔT = temperature

Q= 140 J

Δt = 75 - 60 = 15

mass of the water :

\tt m=\dfrac{Q}{c.\Delta T}=\dfrac{140}{4.18\times 15}=2.23~g

5 0
2 years ago
Calculate the mass of ethyl alcohol required to prepare 540 grams of C4H6, if the reaction follows the scheme:
kkurt [141]

Answer:

Explanation:

2C₂H₅OH    =   C₄H₆  +  2H₂O  +  H₂

2 mole               1 mole

molecular weight of ethyl alcohol

mol weight of C₂H₅OH = 46 gm            

mol weight of C₄H₆  54 gm

540 gm of C₄H₆ = 10 mole

10 mole of C₄H₆ will require 20 mol of ethyl alcohol .

20 mole of ethyl alcohol = 20  x 46

= 920 gm

ethyl alcohol required = 920 gm .

3 0
3 years ago
Write an informal definition of half-life.
Pavel [41]

the time required for the activity of a substance taken into the body to lose one half its initial effectiveness. Informal. a brief period during which something flourishes before dying out.

hope this helps ^^

6 0
2 years ago
Given the following chemical equation, if 50.1 grams of silicon dioxide is heated with excess carbon and 32.3 grams of silicon c
aivan3 [116]

Answer:

97%.

Explanation:

We'll begin by writing the balanced equation for the reaction. This is given below:

SiO2 (s) + 3C (s) —> SiC(s) + 2CO(g)

Next, we shall determine the mass of SO2 that reacted and the mass of SiC produced from the balanced equation. This is illustrated below:

Molar mass of SiO2 = 28 + (16x2) = 60 g/mol

Mass of SO2 from the balanced equation = 1 x 60 = 60 g

Molar mass of SiC = 28 + 12 = 40 g/mol

Mass of SiC from the balanced equation = 1 x 40 = 40 g.

From the balanced equation above,

60 g of SiO2 reacted to produce 40 g of SiC.

Next, we shall determine the theoretical yield of SiC. This can be obtained as follow:

From the balanced equation above,

60 g of SiO2 reacted to produce 40 g of SiC.

Therefore, 50.1 g of SiO2 will react to produce = (50.1 x 40)/60 = 33.4 g of SiC.

Therefore, the theoretical yield of SiC is 33.4 g

Finally, we shall determine the percentage yield of SiC as follow:

Actual yield of SiC = 32.3 g

Theoretical yield of SiC = 33.4 g

Percentage yield =?

Percentage yield = Actual yield /Theoretical yield x 100

Percentage yield = 32.3/33.4 x 100

Percentage yield = 96.7 ≈ 97%

Therefore, the percentage yield of the reaction is 97%.

3 0
3 years ago
WILL GIVE BRAINLIEST ANSWER
OleMash [197]
The correct Answer based on my calculations is C
7 0
3 years ago
Read 2 more answers
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