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2 years ago

Which of the following changes to a pipe would increase the conductance by a factor of 12?

1 answer:

6 0

C. Tripling the length and reducing the radius by a factor of 2 is the change to a pipe would increase the conductance by a factor of 12.

<u>Explanation:</u>

As we know that the resistance is directly proportional to the length of the pipe and it is inversely proportional to the cross sectional area of the pipe.

So it is represented as,

R∝ l /A [ area is radius square]

So k is the proportionality constant used.

R = kl/A

Conductance is the inverse of resistance, so it is given as,

C= 1/R.

R₁ = kl₁ / A₁

R₂ = kl₂/A₂

R₂/R₁ = 1/12 [∵ conductance is the inverse of resistance]

= l₂A₁ / l₁A₂

If we chose l₁/l₂= 3 and A₂/A₁= 4 So R₂/R₁= 1/3×4 = 1/12

So tripling the length and reducing the radius by a factor of 2 would increase the conductance by a factor of 12.

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In a chemical reaction, the element 13al will most preferably ________. in a chemical reaction, the element 13al will most prefe

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Let us calculate the structure of the electric shells of the Al atom. It has an atomic number of 13, so it has 13 electrons. The first 2 go to the first hell. The next 8 need to go to the second shell and the last 3 ones would go to the outermost shell. The outer shell, that is the most important one for chemical reactions, has thus 3 electrons. An atom always tries to have a completed outer shell (with either 2 or 8 atoms). It is easier for a cell to have a charge of +3 than a charge of -5 (smaller absolute value) and thus the Aluminum atom will try to get rid of the 3 electrons. In this process, it loses negative charge thus it will become positively charged. Hence, the correct answer is that it will prefer to lose 3 electrons and become positively charged.

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2 years ago

A first-order reaction (A → B) has a half-life of 25 minutes. If the initial concentration of A is 0.900 M, what is the concentr

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Answer:

0.6749 M is the concentration of B after 50 minutes.

Explanation:

A → B

Half life of the reaction = $t_{1/2}=25 minutes$

Rate constant of the reaction = k

For first order reaction, half life and half life are related by:

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{25 min}=0.02772 min^{-1}$

Initial concentration of A = $[A]_o=0.900 M$

Final concentration of A after 50 minutes = $[A]=?$

t = 50 minute

$[A]=[A]_o\times e^{-kt}$

$[A]=0.900 M\times e^{-0.02772 min^{-1}\times 50 minutes}$

[A] = 0.2251 M

The concentration of A after 50 minutes = 0.2251 M

The concentration of B after 50 minutes = 0.900 M - 0.2251 M = 0.6749 M

0.6749 M is the concentration of B after 50 minutes.

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2 years ago

What is the molar mass of a gas if a flask with a volume of 3. 16 l contains 9. 33 grams of the gas at 32. 0°c and 1. 00 atm?

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The molar mass of a gas if a flask with a volume of 3. 16 L contains 9. 33 grams of the gas at 32. 0°C and 1. 00 atm is 1.17g/mol

Calculation ,

In this question we have to fist find the number of moles of gas by using ideal gas equation and from the help of number of moles we can determine molar mass.

According to ideal gas equation which is also known as ideal law ,

PV = nRT ...( i )

where P is the pressure of the gas = 1 atm

V is the volume of the gas in the flask with volume = 3. 16 L

R is the universal gas constant = 0.082 atm L/K mol

T is the temperature = 32. 0°C = 32 + 273 = 305 K

n is the number of moles = ?

Putting the value of Pressure P , volume V , temperature T , number of moles n and universal gas constant R in the equation (i) we get ,

1 atm ×3. 16 L = n× 0.082 atm L/K mol ×305 K

n = 1 atm ×3. 16 L / 0.082 atm L/K mol × 305 K = 0.126 mole

number of mole of a gas = 0.126 mole = given mass/ molar mass

molar mass = number of moles × Given mass = 0.126 × 9. 33 = 1.17g/mol

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8 months ago

The moon makes light the same way that the sun does.True or False

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Answer: false

Explanation:

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2 years ago

a cube of iron (cp = 0.450 j/g•°c) with a mass of 55.8 g is heated from 25.0°c to 49.0°c. how much heat is required for this pro

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Q = ?

Cp = 0.450 j/g°C

Δt = 49.0ºC - 25ºC => 24ºC

m = 55.8 g

Q = m x Cp x Δt

Q = 55.8 x 0.450 x 24

Q = 602.64 J

hope this helps!

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2 years ago

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