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3 years ago

An area where material from deep within Earth's mantle rises to the crust and melts to form magma is called a

Chemistry

1 answer:

AnnyKZ [126]3 years ago

6 0

Answer:

centro of the eqrhtjrurjfjrnfbfn

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In the early 1960s, radioactive strontium-90 was released during atmospheric testing of nuclear weapons and got into the bones o

Advocard [28]

Answer:

52.54 %

Explanation:

Half life = 29 years

$t_{1/2}=\frac {ln\ 2}{k}$

Where, k is rate constant

So,

$k=\frac {ln\ 2}{t_{1/2}}$

$k=\frac {ln\ 2}{29.0}\ {years}^{-1}$

The rate constant, k = 0.023902 hour⁻¹

From 1964 to 1991:

Time = 27 years

Using integrated rate law for first order kinetics as:

$[A_t]=[A_0]e^{-kt}$

Where,

$[A_t]$ is the concentration at time t

$[A_0]$ is the initial concentration

So,

$\frac {[A_t]}{[A_0]}=e^{-0.023902\times 27}$

$\frac {[A_t]}{[A_0]}=0.5245$

The strontium-90 remains in the bone = 52.54 %

5 0

3 years ago

Under what conditions is the change in internal energy, δe rxn , equal to the heat evolved in a chemical reaction?

Stells [14]

the first law says that the change in internal energy of a system is given by:

δE = δq + δw

where δE is the i change in internal energy, 

δq is the amount of thermal energy added to the system from the surroundings 

δw is the l work done *on* the system *by* the surroundings. 

For a system only undergoing expansion work,
δw = -pδV, so: 

δE = δq - p δV 
when δV = 0, then δe=δq

4 0

2 years ago

Marcela dissolves 80.0 g of ammonium nitrate in 50.0 mL of water at room temperature and notes that the temperature of the solut

seraphim [82]

Answer: The correct answer is A

Explanation:

On addition of the ammonium nitrate to 50 ml of water the temperature decreases which means that reaction between the ammonium nitrate and water is an endothermic reaction.The value of $\Delta H$ is positive for an endothermic reactions.

$\Delta H>0$

Entropy is a degree of randomness of the system.

On addition of the ammonium nitrate to water ammonium nitrate break down into ions which means that entropy is increased.

$\Delta S>0$

$\Delta G=\Delta H-T\Delta S$ (Gibb's free energy)

Since, ammonium nitrate is getting dissolved in water which means that this reaction is spontaneous and $\Delta G$ of spontaneous reaction is negative that is: