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Nutka1998 [239]
3 years ago
10

A mammoth skeleton has a carbon-14 decay rate of 0.49 disintegrations per minute per gram of carbon (0.49 dis/min⋅gC ). You may

want to reference (Pages 950 - 955) section 20.6 while completing this problem. Part A When did the mammoth live? (Assume that living organisms have a carbon-14 decay rate of 15.3 dis/min⋅gC and that carbon-14 has a half-life of 5715 yr.)
Chemistry
1 answer:
jenyasd209 [6]3 years ago
7 0

Answer:

t = 28379.5 years

Explanation:

<u>To find when did the mammoth live, we need to use the exponential decay equation</u>:          

\frac{N_{t}}{N_{0}}= \frac{1}{2}^ \frac{t}{t_{1/2}}  

<em />

<em>where, </em><em>N(t)/N(0): ratio decay rate, t: time to find, t(1/2): half-life</em><em> </em>

   

\frac{0.49}{15.3} = \frac{1}{2}^ \frac{t}{5715}  

Log(0.032) = \frac{t}{5715} \cdot Log(0.5)

t= \frac {5715 \cdot Log(0.032)}{Log(0.5)}  

t= 28379.5 years

Have a nice day!                

     

     

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5 0
3 years ago
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Jack has a rock.the rock has a mass of 14g and a volume of 2cm^3.what is the density of the rock?
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4 0
4 years ago
Consider the reaction: A (aq) ⇌ B (aq) at 253 K where the initial concentration of A = 1.00 M and the initial concentration of B
Ugo [173]

Answer:

The maximum amount of work that can be done by this system is -2.71 kJ/mol

Explanation:

Maximum amount of work denoted change in gibbs free energy (\Delta G) during the reaction.

Equilibrium concentration of B = 0.357 M

So equilibrium concentration of A = (1-0.357) M = 0.643 M

So equilibrium constant at 253 K, K_{eq}= \frac{[B]}{[A]}

[A] and [B] represent equilibrium concentrations

K_{eq}=\frac{0.357}{0.643}=0.555

When concentration of A = 0.867 M then B = (1-0.867) M = 0.133 M

So reaction quotient at this situation, Q=\frac{0.133}{0.867}=0.153

We know,  \Delta G=RTln(\frac{Q}{K_{eq}})

where R is gas constant and T is temperature in kelvin

Here R is 8.314 J/(mol.K), T is 253 K, Q is 0.153 and K_{eq} is 0.555

So, \Delta G=8.314\times 253\times ln(\frac{0.153}{0.555})mol/K

                           = -2710 J/mol

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4 0
3 years ago
I know how to solve it with D=M/V and M1V1 however the answer isn’t correct. Help me please
lara31 [8.8K]

Answer:

23.28 g of O2.

Explanation:

We'll begin by calculating the mass of hexane. This can obtain as follow:

Volume of hexane = 10 mL

Density of hexane = 0.66 g/mL

Mass of hexane =?

Density = mass /volume

0.66 = mass of hexane /10

Cross multiply

Mass of hexane = 0.66 x 10

Mass of hexane = 6.6 g

Next, we shall write the balanced equation for the reaction. This is given below:

2C6H14 + 19O2 —> 12CO2 + 14H2O

Next, we shall determine the masses of C6H14 and O2 that reacted from the balanced equation. This can be obtained as follow:

Molar mass of C6H14 = (12.01x6) + (1.008 x 14)

= 72.06 + 14.112

= 86.172 g/mol

Mass of C6H14 from the balanced equation = 2 x 86.172 = 172.344 g

Molar mass of O2 = 16x2 = 32 g/mol

Mass of O2 from the balanced equation = 19 x 32 = 608 g

From the balanced equation above,

172.344 g of C6H14 reacted with 608 g of O2.

Finally, we shall determine the mass of O2 needed to react with 10 mL (i.e 6.6 g) of hexane, C6H14. This can be obtained as follow:

From the balanced equation above,

172.344 g of C6H14 reacted with 608 g of O2.

Therefore, 6.6 g of C6H14 will react with = (6.6 x 608)/172.344 = 23.28 g of O2.

Therefore, 23.28 g of O2 is needed for the reaction.

8 0
3 years ago
A radioactive isotope of potassium (k) has a half-life of 20 minutes. if a 43 gram sample of this isotope is allowed to decay fo
Ksenya-84 [330]

Hello!

The half-life is the time of half-disintegration, it is the time in which half of the atoms of an isotope disintegrate.

We have the following data:

mo (initial mass) = 43 g

m (final mass after time T) = ? (in g)

x (number of periods elapsed) = ?

P (Half-life) = 20 minutes

T (Elapsed time for sample reduction) = 80 minutes

Let's find the number of periods elapsed (x), let us see:

T = x*P

80 = x*20

80 = 20\:x

20\:x = 80

x = \dfrac{80}{20}

\boxed{x = 4}

Now, let's find the final mass (m) of this isotope after the elapsed time, let's see:

m =  \dfrac{m_o}{2^x}

m =  \dfrac{43}{2^{4}}

m = \dfrac{43}{16}

\boxed{\boxed{m = 2.6875\:g}}\end{array}}\qquad\checkmark

I Hope this helps, greetings ... DexteR! =)

8 0
4 years ago
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