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2 years ago

13

A chemist needs 15.0 grams of ethanol for a reaction. If the density of ethanol is 0.789 g/ml, how many milliliters of alcohol s

hould be used?

1 answer:

harina [27]2 years ago

3 0

Mass=15g
Density=0.789g/ml

$\\ \bull\tt\dashrightarrow Density=\dfrac{Mass}{Volume}$

$\\ \bull\tt\dashrightarrow Volume=\dfrac{Mass}{Density}$

$\\ \bull\tt\dashrightarrow Volume=\dfrac{15}{0.789}$

$\\ \bull\tt\dashrightarrow Volume=19.01mL$

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Two forces, F? 1 and F? 2, act at a point, as shown in the picture. (Figure 1) F? 1 has a magnitude of 9.20 N and is directed at

Stolb23 [73]

Answer:

a. Fx = -8.089 N b. Fy = 3.525 N c. 8.824 N d. 336.45°

Explanation:

Since F₁ = 9.2 N and acts at 57° above the negative axis in the second quadrant, its x-component is -F₁cos57° and its y- component is F₁sin57°

Since F₁ = 5.2 N and acts at 53.7° below the negative axis in the third quadrant, its x-component is -F₂cos53.7° and its y- component is -F₂sin53.7°

Part A

What is the x component Fx of the resultant force?

The x component of the resultant force Fx = -F₁cos57° + -F₂cos53.7° = -9.2cos57° + (-5.2cos53.7°) = (-5.011 - 3.078) N = -8.089 N

Part B

What is the y component Fy of the resultant force?

The y component Fy of the resultant force = F₁sin57° + -(F₂sin53.7°) = 9.2sin57° - 5.2sin53.7° = (7.716 - 4.191) N = 3.525 N

Part C

What is the magnitude F of the resultant force?

The magnitude F of the resultant force = √(Fx² + Fy²)

F = √(-8.089² N + 3.525² N) = √65.432 + 12.426 = √77.858 = 8.824 N

Part D

What is the angle ? that the resultant force forms with the negative x axis?

The angle the resultant force makes with the negative x axis is given by

θ = tan⁻¹(Fy/Fx) = tan⁻¹(3.525/-8.089) = tan⁻¹-0.4358 = -23.55°.

To measure it from the negative x axis, we add 360. So, our angle = 360 -23.55 = 336.45°

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2 years ago

Find the electron and hole mobilities, and the resistivity of intrinsic silicon at 300K. Is intrinsic silicon a semiconductor

tino4ka555 [31]

Answer:

Resistivity = 231.481 K Ohm

Yes, Intrinsic Silicon is the semiconductor.

Explanation:

Solution:

At 300K:

Let suppose mobility of electron in intrinsic semiconductor = $M_{e}$

Mobility of electron in intrinsic semiconductor is:

$M_{e}$ = 1300 $cm^{2}$ /volt.sec

Let suppose mobility of hole in intrinsic semiconductor = $M_{h}$

$M_{h}$ = 500 $cm^{2}$ /volt.sec

We know that, intrinsic silicon semiconductor has equal number of holes and electrons. So,

At 300 K

Intrinsic Carrier Concentration = 1.5 x $10^{10}$ / $cm^{3}$ = C

And,

Conductivity of intrinsic Silicon is:

σ = C x ( $M_{h}$ + $M_{e}$ ) e

e = 1.6 x $10^{-19}$ C

So, plugging in the values, we get:

σ = C x ( $M_{h}$ + $M_{e}$ ) e

σ = 1.5 x $10^{10}$ x (500 + 1300) x 1.6 x $10^{-19}$

σ = 4.32 x $10^{-6}$

So, now we can find the resistivity.

Resistivity = 1/σ

Resistivity = 1/ 4.32 x $10^{-6}$

Resistivity = 231.481 K Ohm

Yes, Intrinsic Silicon is the semiconductor.

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snow_tiger [21]

Answer:

Explanation:

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Even with all of these state changes, it is important to remember that the substance stays the same—it is still water, which consists of two hydrogen atoms and one oxygen atom. Changing states of matter are only physical changes; the chemical properties of the matter stays the same regardless of its physical state!

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polet [3.4K]

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When a hot and cold object are placed in contact, the hot one loses energy. Does this violate energy conservation? Why or why no

blsea [12.9K]

Answer:

This does not violate the conservation of energy.

Explanation:

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