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3 years ago

3. describe natural sources of radiation. infer some of the dangers that radiation can impose.

Chemistry

1 answer:

maxonik [38]3 years ago

4 0

Answer:

All of us are exposed to radiation every day, from natural sources such as minerals in the ground, and man-made sources such as medical x-rays. According to the National Council on Radiation Protection and Measurements (NCRP), the average annual radiation dose per person in the U.S. is 6.2 millisieverts (620 millirem).

Explanation:

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How many atoms of N are in 0.82 g of NaNO3? ( molar conversion)

VMariaS [17]

The number of atoms N = 5.8 x 10²¹

<h3>Further explanation</h3>

A mole is a unit of many particles (atoms, molecules, ions) where 1 mole is the number of particles contained in a substance that is the same amount as many atoms in 12 gr C-12

1 mole = 6.02.10²³ particles

mass of N in 0.82 g of NaNO₃ (MW NaNO₃: 85 g/mol) :

$\tt mass~N=\dfrac{Ar~N}{MW~NaNO_3}\times mass~NaNO_3\\\\mass~N=\dfrac{14}{85}\times 0.82\\\\mass~N=0.135~g$

moles of N :

$\tt mol=\dfrac{mass}{Ar}\\\\mol=\dfrac{0.135}{14}=0.0096$

The number of atoms N :

$\tt N=n\times No\\\\N=0.0096\times 6.02\times 10^{23}\\\\N=5.8\times 10^{21}~atoms$

4 0

3 years ago

Suppose 650.mmol of electrons must be transported from one side of an electrochemical cell to another in 10.0 minutes. Calculate

Alina [70]

Answer:

The size of electric current must 104.5 Ampere.

Explanation:

Moles of electrons = 650 mmol = $650\times 0.001 mol$

mmol = 0.001 mol

1 mol = $N_A=6.022\times 10^{23}$ atoms/ions

Number of electrons = N

N = $650\times 0.001\times 6.022\times 10^{23}=3.9143\times 10^{23}$

Charge on an electron = $1.602\times 10^{-19} C$

Total charge on N electrons = Q

$Q=3.9143\times 10^{23}\times 1.602\times 10^{-19} C=62,707.086 C$

Duration of time = T = 10 min = 10 × 60 s

1 minute = 60 seconds

$Current(I)=\frac{Charge(Q)}{Time(T)}$

$I=\frac{62,707.086 C}{10\times 60 s}=104.5 A$

The size of electric current must 104.5 Ampere.

8 0

3 years ago

Blast furnaces extra pure iron from the Iron(IIl)oxide in iron ore in a two step sequence. In the first step, carbon and oxygen

OLga [1]

Answer:

5.9 kg

Explanation:

We must work backwards from the second step to work out the mass of oxygen.

1. Second step

Mᵣ: 55.84

Fe₂O₃ + 3CO ⟶ 2Fe + 3CO₂

m/kg: 7.0

(a) Moles of Fe

$\text{Moles of FeO} = \text{7000 g Fe} \times \dfrac{\text{1 mol Fe}}{\text{55.84 g Fe}} = \text{125 mol Fe}$

(b) Moles of CO

$\text{Moles of CO} = \text{125 mol Fe} \times \dfrac{\text{3 mol CO}}{\text{2 mol Fe}} = \text{188 mol CO}$

However, this is the theoretical yield.

The actual yield is 72. %.

We need more CO and Fe₂O₃ to get the theoretical yield of Fe.

(c) Percent yield

$\begin{array}{rcl}\text{Percent yield} &=& \dfrac{\text{ actual yield}}{\text{ theoretical yield}} \times 100 \, \%\\\\ 72. \, \% & = & \dfrac{\text{188 mol}}{\text{actual yield}} \times 100 \,\%\\\\0.72 &= &\dfrac{\text{188 mol}}{\text{actual yield}}\\\\\text{Actual yield} & = & \dfrac{\text{188 mol}}{0.72}\\& = & \textbf{261 mol}\\\\\end{array}$

We must use 261 mol of CO to get 7.0 kg of Fe.

2. First step

Mᵣ: 32.00

2C + O₂ ⟶ 2CO

n/mol: 261

(a) Moles of O₂

$\text{Moles of O}_{2} = \text{261 mol CO} \times \dfrac{\text{1 mol O}_{2}}{\text{2 mol CO}} = \text{131 mol O}_{2}$

(b) Mass of O₂

$\text{Mass of O}_{2}= \text{131 mol O }_{2} \times \dfrac{\text{32.00 g O}_{2}}{\text{1 mol O}_{2}} = \text{4180 g O}_{2}$

However, this is the theoretical yield.

The actual yield is 71. %.

We need more C and O₂ to get the theoretical yield of CO.

(c) Percent yield

$\begin{array}{rcl}71. \, \% & = & \dfrac{\text{188 mol}}{\text{actual yield}} \times 100 \,\%\\\\0.71 &= &\dfrac{\text{4180 g}}{\text{actual yield}}\\\\\text{Actual yield} & = & \dfrac{\text{4180 g}}{0.71}\\\\& = & \text{5900 g}\\& = & \textbf{5.9 kg}\\\end{array}$

We need 5.9 kg of O₂ to produce 7.0 kg of Fe.

6 0

4 years ago

What happens when two objects when they are brought closer together The mass of both objects decrease The mass of both objects i

Maurinko [17]

Answer:

The correct option is

The gravitational force between them increases

Explanation:

According to Newton's law of universal gravitation states that the force of attraction between two bodies is directly proportional to the product of the masses of the bodies and inversely proportional to the square of the distance of their centers from each other.

The formula for universal gravitation is given as follows;

$F_{1} = F_{2} =G \times \dfrac{m_{1} \times m_{2}}{r^{2}}$

Where;

F₁, and F₂ = The gravitational forces of attraction on each mass

G = The gravitational constant

m₁ = The mass of one body

m₂ = The mass of the body

r = The distance between the centers of the two bodies

Therefore, the gravitational force of attraction on each object is inversely proportional to the as the distance between the centers of the two bodies

When the distance between the centers of the two bodies decreases, the two objects are brought closer together, the gravitational force of attraction between them increases.

8 0

3 years ago

Please help me need help.

skelet666 [1.2K]

Electrons are able to "move" around the atom in set energy states in different orbitals, because the electrons "move" so fast around the nucleus where they are is just represented with an area of probability since their location and velocity cannot be measured with certainty. Protons and Neutrons are packed tightly in the nucleus held together by the strong nuclear force so they are not able to freely move.

4 0

4 years ago