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3 years ago

What do you need to adjust to balance a chemical equation

Chemistry

2 answers:

Nataliya [291]3 years ago

8 0

You always adjust numbers and it will be before the element
so you Neva add or change a subscript

Charra [1.4K]3 years ago

8 0

Subscript
Is what you will need in order to adjust the balance of the chemical equation

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A certain radioactive isotope decays at a rate of 0.2% annually. Determine the half-life of this isotope, to the nearest year

pychu [463]

Answer:

The half-life of the radioactive isotope is 346 years.

Explanation:

The decay rate of the isotope is modelled after the following first-order linear ordinary differential equation:

$\frac{dm}{dt} = -\frac{m}{\tau}$

Where:

$m$ - Current isotope mass, measured in kilograms.

$t$ - Time, measured in years.

$\tau$ - Time constant, measured in years.

The solution of this differential equation is:

$m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }$

Where $m_{o}$ is the initial mass of the isotope. It is known that radioactive isotope decays at a yearly rate of 0.2 % annually, then, the following relationship is obtained:

$\%e = \frac{m(t)-m(t+1)}{m(t)}\times 100\,\% = 0.2\,\%$

$1 - \frac{m(t+1)}{m(t)} = 0.002$

$1 - \frac{m_{o}\cdot e^{-\frac{t+1}{\tau} }}{m_{o}\cdot e^{-\frac{t}{\tau} }}=0.002$

$1 - e^{-\frac{1}{\tau} } = 0.002$

$e^{-\frac{1}{\tau} } = 0.998$

$-\frac{1}{\tau} = \ln 0.998$

The time constant associated to the decay is:

$\tau = -\frac{1}{\ln 0.998}$

$\tau \approx 499.500\,years$

Finally, the half-life of the isotope as a function of time constant is given by the expression described below:

$t_{1/2} = \tau \cdot \ln 2$

If $\tau \approx 499.500\,years$ , the half-life of the isotope is:

$t_{1/2} = (499.500\,years)\cdot \ln 2$

$t_{1/2}\approx 346.227\,years$

The half-life of the radioactive isotope is 346 years.

6 0

2 years ago

Silver can be electroplated at the cathode of an electrolysis cell by the half-reaction. Ag+(aq)+e−→Ag(s) Part A Silver can be e

dmitriy555 [2]

Answer: Mass of silver deposited at the cathode is 37.1g

Explanation: According to Faraday Law of Electrolysis, the mass of substance deposited at the electrode (cathode or anode) is directly proportional to quantity of electricity passed through the electrolyte

Faraday has found that to liberate one gm eq. of substance from an electrolyte, 96500C of electricity is required.

$Ag^+$ +e− ==> Ag(s)

Given that

Current (I) = 8.5A

Time (t) = 65 *60 = 3900s

Quantity of electricity passed = 8.5*3900 =33150C

Molar mass of Ag= 108g

96500C will liberate 108g

33150C will liberate Xg

Xg= (108*33150)/96500

=37.1g

Therefore the mass of Ag deposited at the cathode is 37.1g.

3 0

2 years ago

Calculate the energy of an electron in the n = 2 level of a hydrogen atom.

ANEK [815]

Answer: The energy of an electron in the n = 2 level of a hydrogen atom is 3.40 eV.

Explanation:

Given: n = 2

The relation between energy and $n^{th}$ orbit of an atom is as follows.

$E = - \frac{13.6}{n^{2}} eV$

Substitute the values into above formula as follows.

$E = - \frac{13.6}{n^{2}} eV\\= - \frac{13.6}{(2)^{2}}\\= - 3.40 eV$

The negative sign indicates that energy is being released.

Thus, we can conclude that the energy of an electron in the n = 2 level of a hydrogen atom is 3.40 eV.

5 0

2 years ago

What kind of chemical reaction does the chemical equation sodium + chlorine → sodium chloride represent? combustion decompositio

horsena [70]

The answer is D, synthesis.

4 0

2 years ago

How many atoms are in 2.85x10^3 g of gallium

OLga [1]

Answer:

2850 grams I hope this help

8 0

2 years ago