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posledela
3 years ago
13

How many electrons are in 0.990 oz of a pure gold coin?

Chemistry
1 answer:
sleet_krkn [62]3 years ago
7 0

Atomic number of gold, Au = 79 means there are 79 electrons in per atom of gold.

Atomic mass of gold = 196.967 gm

0.990 oz of gold is given.

Now, converting oz to gm

1 oz = 28.3495 gm

So, 0.990 oz = 0.990\times 28.3495 gm = 28.066 gm

Now, for determining the number of moles, the formula for number of moles is:

number of moles = \frac{given mass}{Molar mass}

Substituting the values:

number of moles = \frac{28.066}{196.967} = 0.1425 mole

1 mole of Au = 6.022\times 10^{23} atoms of Au

So, for 0.1425 mole of Au = 6.022\times 10^{23}\times 0.1425 atoms of Au = 0.8581 \times 10^{23} atoms of Au

Since 1 atom of gold has 79 electrons so,

Number of electrons = 0.8581 \times 10^{23}\times 79 = 67.7899\times 10^{23} electrons

So, number of electrons in 0.990 oz of pure gold coin is 67.7899\times 10^{23}.

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Answer: In the chemical formula for water, the subscript for hydrogen is 2. Notice that the 2 is smaller and written slightly below the H and O. It is called a subscript because it is written ("script") "below" ("sub") the preceding letter.

Explanation:

4 0
3 years ago
What is the molarity of a solution that contains 122g of MgSO4 n 3.5L of solution?​
Semmy [17]

Answer:

0.29mol/L or 0.29moldm⁻³

Explanation:

Given parameters:

Mass of MgSO₄ = 122g

Volume of solution = 3.5L

Molarity is simply the concentration of substances in a solution.

Molarity = number of moles/ Volume

>>>>To calculate the Molarity of MgSO₄ we find the number of moles using the mass of MgSO₄ given.

Number of moles = mass/ molar mass

Molar mass of MgSO₄:

Atomic masses: Mg = 24g

S = 32g

O = 16g

Molar mass of MgSO₄ = [24 + 32 + (16x4)]g/mol

= (24 + 32 + 64)g/mol

= 120g/mol

Number of moles = 122/120 = 1.02mol

>>>> From the given number of moles we can evaluate the Molarity using this equation:

Molarity = number of moles/ Volume

Molarity of MgSO₄ = 1.02mol/3.5L

= 0.29mol/L

IL = 1dm³

The Molarity of MgSO₄ = 0.29moldm⁻³

8 0
3 years ago
Approximately how many particles are in 2 moles?
schepotkina [342]

Answer:

1.2\times10^2^4 particles in 2 moles.

Explanation:

The number of particles that are contained in one mole, the international unit of amount of substance: by definition, exactly 6.022×10²³, and it is dimensionless. It is named after the scientist Amedeo Avogadro.

It is also known as Avogadro's constant.

∴ Number of particles in one mole = 6.022\times10^2^3

∴ Number of particles in 2 mole = 2 times Number of particles in one mole

∴ Number of particles in 2 mole=2\times6.022\times10^2^3=12.044\times10^2^3\approx1.2\times10^2^4

Hence there are 1.2\times10^2^4 particles in 2 moles.

4 0
2 years ago
Read 2 more answers
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dlinn [17]

Answer:

Explanation:

The absorbed sunlight drives photosynthesis, fuels evaporation, melts snow and ice, and warms the Earth system. Solar power drives Earth's climate. Energy from the Sun heats the surface, warms the atmosphere, and powers the ocean currents.

7 0
2 years ago
Electron A falls from energy level X to energy level Y and releases blue light. Electron B falls from energy level Y to energy l
MrMuchimi

Answer: Transition from X to Y will have greater energy difference.

Explanation: For studying the energy difference, we require Planck's equation.

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where, h = Planck's Constant

c = Speed of light

E = Energy

\lambda = Wavelength of particle

From the equation, it is visible that the energy and wavelength follow inverse relation which means that with low wavelength value, energy will be the highest and vice-versa.

As electron A falls from X-energy level to Y-energy level, it releases blue light which has low wavelength value (around 470 nm) which means that it has high energy.

Similarly, Electron B releases red light when it falls from Y-energy level to Z-energy level, which has high wavelength value (around 700 nm), giving it a low energy value.

Energy Difference between X-energy level and Y-energy level will be more.


5 0
3 years ago
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