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3 years ago

11. A 4.175 gram sample of a certain hydrate of copper (II) sulfate, CuSO,• xH,O, is heated until all

Chemistry

1 answer:

Wewaii [24]3 years ago

3 0

The formula of the hydrate = CuSO₄• 3H₂O

<h3>Further explanation</h3>

Given

4.175 grams sample CuSO₄• xH₂O

3.120 grams anhydrous compound CuSO₄

Required

The formula

Solution

mass of H₂O driven off :

= 4.175 - 3.12

= 1.055 g

MW CuSO₄ = 159.5 g/mol

MW H₂O = 18 g/mol

mol ratio of CuSO₄ : H₂O :

= 3.12/159.5 : 1.055/18

= 0.01956 : 0.05861

= 1 : 3

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2 years ago

Please help me, I really don't want to fail but I don't know how to do this

Brrunno [24]

Answer:

<u>12 moles</u>

Explanation:

$NH_{3}(g) + O_{2}(g) \: → NO_{2} + H_{2}O(g)$

__↑______↑

8.00 mol | 14.00 mol

________________

$NH_{3}(g) + O_{2}(g) \: → NO_{2} + H_{2}O(g)$

You can turn this into a system of variables which are solvable.

To do this, create variables for the coefficients of each compound in the reaction respectively.

$a(NH_{3}(g)) + b(O_{2}(g)) → \\c(NO_{2}) + d(H_{2}O(g))$

Because to be balanced, the count of atoms in each element of the compound correspond to the coefficient of the variable in that compound so that the count of the left (reactant) side is set equal to the right (product) side.

a corresponds to the coefficient of the first compound, b corresponds to the coefficient of the second compound, c corresponds to the coefficient of the third compound, and d corresponds to the coefficient of the fourth compound.

(Reactant = Product)

Reactant: 1a [N] Product: 1c.

Reactant: 3a [H] Product: 2d.

Reactant: 2b [O] Product: 2c + 1d.

Thus the system is:

1a = 1c

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2 years ago

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

Approximately how often does the moon revolve around the earth?

dmitriy555 [2]

Answer: A

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2 years ago

HELP i need the answer to this science question:

S_A_V [24]

Answer:

1. Convection: c. Transfer of energy by movement of matter.

2. Radiation: e. Transfer of energy by waves, often through empty space.

3. Thermal Energy: a. The total energy an object has. The more stuff you have the higher this will be.

4. Conduction: d. Transfer of energy by contact between two things.

5. Heat: b. Any transfer of thermal energy

______________________

<h2>Explanation(s):</h2>

<u>Explanation of #1</u>:

Convection is one of the three ways thermal energy is transferred. Convection is usually defined as the transfer of heat by the circulation or movement of the heated parts of a liquid or gas. An example of convection on earth is convection currents. Convection currents are the movement of fluid as a result of differential heating or convection. In the case of the Earth, convection currents refer to the motion of molten rock in the mantle as radioactive decay heats up magma, causing it to rise and riving the global-scale flow of magma.

<u>Explanation for #2:</u>

Electromagnetic waves are waves produced the acceleration of an electric charge and propagated by the periodic variation of intensities of, usually, perpendicular electric and magnetic fields. This transfer of energy by waves is known as radiation. Or in other words, this kind of transfer is done through the propagation of electromagnetic waves, that carry energy, without need of a material medium, in empty space. Radiation is usually defined as the complete process in which energy is emitted by one body, transmitted through an intervening medium or space, and absorbed by another body.

<u>Explanation for #3</u>:

Thermal energy can be defined in 3 different ways. First, it can be defined as the internal energy of a system in thermodynamic equilibrium due to its temperature. Second, A form of energy; sensible energy; heat. Third and last, the energy released by an explosion. Thermal energy is produced through the movement of particles within a system or object, it can be referred to as kinetic energy. Kinetic energy is usually defined as the energy of a body or a system with respect to the motion of the body or of the particles in the system.

<u>Explanation of #4</u>:

Conduction is usually defined as the transfer of heat between two parts of a stationary system, caused by a temperature difference between the parts. Conduction is the transfer of heat through direct touch of molecules. Conduction is the transfer of thermal energy with no transfer of manner. It occurs when two materials touch. The heat movement in conduction is within and via the body itself. In contrast, heat transmission through thermal radiation frequently occurs between entities that are geographically separated. Heat can also be transferred by a mix of conduction and thermal radiation.

<u>Explanation of #5</u>:

As a noun, heat is usually defined as the state of a body perceived as having or generating a relatively high degree of warmth. There are 3 types of ways heat can be transferred which is via conduction, convection, or radiation. Heat produces thermal energy which is transmission through these 3 different processes. Thermal energy is the internal energy of a system in thermodynamic equilibrium due to it's temperature. Thermal energy is produced through heat and is transmission through the 3 processes in different ways (mentioned above obviously).

___________

<h3>additional comment:</h3>

Definitions:

Radiation is simply the energy that is emitted by a body that has energy. Even human beings radiate energy (infra red radiation).

Convection is the transfer of heat through fluid (liquid or gas). It probably relates to astronomy in that due to gravity, a star's core is much hotter than the rest of it. The heated plasma rises to the surface like boiling water, where the heat is absorbed by the surrounding plasma through convection , then it cools and sinks down to the core again.

In the atmosphere conduction is the transfer of heat by direct contact. The best example would be the heating of the atmosphere that is directly in contact with the Earth (first few feet).

On a particle level this is energy transferred by the particles colliding with and passing energy into adjacent particles.

5 0

1 year ago