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3 years ago

Does anyone know this? help please

Chemistry

1 answer:

Sav [38]3 years ago

7 0

Explanation:

The substance that is in excess that doesn't get used up as a reactant is called limiting reactant.

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(a) Calculate the energy released by the alpha decay of 222 86Rn.

Alinara [238K]

Answer:

a). The energy released by the alpha decay of 222 Rn is to 218 Po :

= 5.596 MeV

b).The energy of the alpha particle is 5.5 MeV

c) The recoil energy of Po = 0.096 MeV

Explanation:

The equation for the alpha decay of Rn to Polonium is:

$_{86}^{222}\textrm{Rn}\rightarrow$ $_{2}^{4}\textrm{He}+_{84}^{218}\textrm{Po}$

The energy of the decay process can be calculated using:

$\Delta E=\Delta mc^{2}$

$\Delta m$ = Change in the mass

Mass of Po = 218.008965 u

Mass of He = 4.002603 u

Mass of Rn = 222.017576 u

$\Delta m$ = mass of Po + mass of He - mass of Rn

= 4.002603 + 218.008965-222.017576

= - 0.006008

$\Delta E=m(931.5MeV)$

$\Delta E=-0.006008\times 931.5MeV$

= -5.596 MeV

The negative sign means energy is released during the process.

b) The energy of the alpha particle is :

$\frac{Po\ mass }{Rn\ mass}\times E$

$\frac{218.0089}{222.0175}\times \Delta E$

$\frac{218.0089}{222.0175}\times 5.596$

= 5.494 MeV

= 5.5 MeV

c).

Recoil energy: When the parent nucleus is at rest before the decay then , there must be the some recoil of daughter nucleus to conserve the momentum.This is termed as recoil energy.

The energy of the recoil polonium atom :

The formula for recoil energy is :

The total energy - the kinetic energy

= 5.596 - 5.5

= 0.096 MeV

7 0

3 years ago

2. Why do ions form?

noname [10]

Answer:

When atoms lose or gain electrons, they become positively or negatively charged ions. In an ionic compound, the ions are arranged in a three-dimensional structure called a crystal. ... When an atoms gains or loses electrons, it gains a charge, thus becoming an ion.

Explanation:

7 0

3 years ago

Read 2 more answers

Marshall determines that a gas has a gage pressure of 276 kPa what's the absolute pressure of this gas

Wittaler [7]

To determine the absolute pressure of this gas, all you need to do is to add the value of atmospheric pressure and the value of gage pressure.

Atmospheric pressure is equivalent to 100 kPa.
Gage pressure is 276 kPa.

Then, we add both values.

N = 100 kPa + 276 kPa
N = 376 kPa

The absolute pressure of this gas is 376 kPa.

Hope this helps :)

3 0

4 years ago

Read 2 more answers

A reaction is second order respect to the reactant A. If the reaction is 85% complete in 12 minutes, how long would it take for

AnnZ [28]

Answer:

e. 22s

Explanation:

Initial Concentration = 100

Final concentration = 15 ( Since the reaction is 85% complete)

Time = 12 minutes = 720 seconds

The integrated rate law for second order reactions is given as;

1 / [A] = (1 / [A]o) + kt

Making k subject of interest, we have;

kt = (1 / [A] ) - (1 / [A]o )

k = (1 / [A] ) - (1 / [A]o ) / t

k = [(1/ 15) - (1 / 100) ] / 720

k = (0.0667 - 0.01 ) / 720

k = 0.0567 / 720

k = 7.875e^-5

How long would it take for the reaction to be 15% complete?

Final concentration = 85 (Since the reaction would be 15% complete)

The integrated rate law for second order reactions is given as;

1 / [A] = (1 / [A]o) + kt

Making t subject of interest, we have;

kt = (1 / [A] ) - (1 / [A]o )

t = (1 / [A] ) - (1 / [A]o ) / k

t = [(1 / 85 ) - (1 / 100) ] / 7.875e^-5

t = (0.0117 - 0.01 ) / 7.875e^-5

t = 0.001765 / 7.875e^-5

t = 22.41 seconds

Corect option = E.

3 0

3 years ago

Hello!! I need help please! Please explain how I can identify a percipitate in a reaction! I need help with chemistry ha

antiseptic1488 [7]

Generally speaking a precipitate is something that will form as a result of the reaction. It generally is a solid material.

Sodium and nitrates are soluble so Calcium Phosphate would precipitate out....

5 0

3 years ago