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Sergio [31]
3 years ago
14

If a substance has a half life of 58 years and starts with 500 g radioactive, how much remains radioactive after 30 years?

Chemistry
1 answer:
Vilka [71]3 years ago
5 0

Answer:

A = 349 g.

Explanation:

Hello there!

In this case, since the radioactive decay kinetic model is based on the first-order kinetics whose integrated rate law is:

A=Ao*exp(-kt)

We can firstly calculate the rate constant given the half-life as shown below:

k=\frac{ln(2)}{t_{1/2}} =\frac{ln(2)}{58year}=0.012year^{-1}

Therefore, we can next plug in the rate constant, elapsed time and initial mass of the radioactive to obtain:

A=500g*exp(-0.012year^{-1} *30year)\\\\A=349g

Regards!

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3. How many moles are 1.707 x 10^24 atoms of carbon?
Paraphin [41]

Answer:

2.835 moles of carbon

Explanation:

By definition, there are 6.022x10^23 atoms (or compounds) in one mole.

Write and use this as a conversion factor:

(6.022x10^23 atoms)/mole

(1.707 x 10^24 atoms of carbon)/((6.022x10^23 atoms)/mole) = 2.835 moles carbon

8 0
2 years ago
Wet steam at 1100 kPa expands at constant enthalpy (as in a throttling process) to 101.33 kPa, where its temperature is 105°C. W
nikklg [1K]

Answer:

There are 3 steps of this problem.

Explanation:

Step 1.

Wet steam at 1100 kPa expands at constant enthalpy to 101.33 kPa, where its temperature is 105°C.

Step 2.

Enthalpy of saturated liquid Haq = 781.124 J/g

Enthalpy of saturated vapour Hvap = 2779.7 J/g

Enthalpy of steam at 101.33 kPa and 105°C is H2= 2686.1 J/g

Step 3.

In constant enthalpy process, H1=H2 which means inlet enthalpy is equal to outlet enthalpy

So, H1=H2

     H2= (1-x)Haq+XHvap.........1

    Putting the values in 1

    2686.1(J/g) = {(1-x)x 781.124(J/g)} + {X x 2779.7 (J/g)}

                        = 781.124 (J/g) - x781.124 (J/g) = x2779.7 (J/g)

1904.976 (J/g) = x1998.576 (J/g)

                     x = 1904.976 (J/g)/1998.576 (J/g)

                     x = 0.953

So, the quality of the wet steam is 0.953

                   

7 0
3 years ago
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topjm [15]

Answer:

1.94

Explanation:

moles = mass/Mr so you have 3.889 moles of aluminium, but because the ratio in the equation is 2:1 you need to halve it.

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3 years ago
What common item can detect the presence of radiation? A. Bleach B. A roll of photographic film C. LED watch D. Baking soda
Alenkinab [10]

Answer: B- a roll of photographic film

Explanation:

Founders education answer

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2 years ago
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