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sdas [7]
3 years ago
8

Subsurface mining disturbs more land than surface mining true or false

Chemistry
1 answer:
Allisa [31]3 years ago
5 0

Answer:

False

Explanation:

Surface mining disturbs more land compared to subsurface mines.

During surface mining, huge mounds of earth is removed inorder to access mineral deposits. The deeper lying the deposit, the more the earth is removed and disturbed.

In subsurface mines, tunnels and a system of shaft are used to access the ore body. Data about the geometry and positioning of the ore helps to plan how to effectively access it.

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If an ice cube weighing 25.0 g with an initial
riadik2000 [5.3K]

Answer:

11

∘

C

Explanation:

As far as solving this problem goes, it is very important that you do not forget to account for the phase change underwent by the solid water at

0

∘

C

to liquid at

0

∘

C

.

The heat needed to melt the solid at its melting point will come from the warmer water sample. This means that you have

q

1

+

q

2

=

−

q

3

(

1

)

, where

q

1

- the heat absorbed by the solid at

0

∘

C

q

2

- the heat absorbed by the liquid at

0

∘

C

q

3

- the heat lost by the warmer water sample

The two equations that you will use are

q

=

m

⋅

c

⋅

Δ

T

, where

q

- heat absorbed/lost

m

- the mass of the sample

c

- the specific heat of water, equal to

4.18

J

g

∘

C

Δ

T

- the change in temperature, defined as final temperature minus initial temperature

and

q

=

n

⋅

Δ

H

fus

, where

q

- heat absorbed

n

- the number of moles of water

Δ

H

fus

- the molar heat of fusion of water, equal to

6.01 kJ/mol

Use water's molar mass to find how many moles of water you have in the

100.0-g

sample

100.0

g

⋅

1 mole H

2

O

18.015

g

=

5.551 moles H

2

O

So, how much heat is needed to allow the sample to go from solid at

0

∘

C

to liquid at

0

∘

C

?

q

1

=

5.551

moles

⋅

6.01

kJ

mole

=

33.36 kJ

This means that equation

(

1

)

becomes

33.36 kJ

+

q

2

=

−

q

3

The minus sign for

q

3

is used because heat lost carries a negative sign.

So, if

T

f

is the final temperature of the water, you can say that

33.36 kJ

+

m

sample

⋅

c

⋅

Δ

T

sample

=

−

m

water

⋅

c

⋅

Δ

T

water

More specifically, you have

33.36 kJ

+

100.0

g

⋅

4.18

J

g

∘

C

⋅

(

T

f

−

0

)

∘

C

=

−

650

g

⋅

4.18

J

g

∘

C

⋅

(

T

f

−

25

)

∘

C

33.36 kJ

+

418 J

⋅

(

T

f

−

0

)

=

−

2717 J

⋅

(

T

f

−

25

)

Convert the joules to kilojoules to get

33.36

kJ

+

0.418

kJ

⋅

T

f

=

−

2.717

kJ

⋅

(

T

f

−

25

)

This is equivalent to

0.418

⋅

T

f

+

2.717

⋅

T

f

=

67.925

−

33.36

T

f

=

34.565

0.418

+

2.717

=

11.026

∘

C

Rounded to two sig figs, the number of sig figs you have for the mass of warmer water, the answer will be

T

f

=

11

∘

C

Explanation:

3 0
3 years ago
What is the pH of a solution that has a [OH-] of 5.08x10^-5 M
sattari [20]

Answer:

The pH of a solution that has a [OH-] of 5.08x10^-5 M is 5

Explanation:

just took the test

onedg2020

3 0
2 years ago
A hydroelectric dam produces renewable energy for the local area. Which best explains why more hydroelectric dams are not built?
romanna [79]

Answer:

The dam disrupts the river wildlife and ecosystem.

Explanation:

Though it is believed that using the dam as a power generation or hydroelectric power supply generates no greenhouse gases, it, however, has many disadvantages which make it deemed not suitable or sustainable for use in the contemporary time.

Majorly, the top reason why more hydroelectric dams are not built is that "the dam disrupts the river wildlife and ecosystem."

Also, it affects the water quality and other use of water for humans such as recreational use.

There is also a possible chance of dams producing methane; a greenhouse gas through the organic materials in the water that is rotting.

7 0
3 years ago
How many moles of carbon and hydrogen are needed to produce 10 mol of ethylene
alekssr [168]
I think 1.00 mol sorry if I’m wrong
7 0
3 years ago
How many grams of fluorine are needed to react with 8.5g of phosphorus?
love history [14]

Step 1: write the equation:

                                          P₄(s) + 6F₂(g) → 4PF₃(g) 


Step 2: Molar mass of P₄ = 30.97 g/mol × 4 = 123.88 g/mol


Step 3: Number of moles of phosphorus

                                                    n = m/M 

                                                    n = 8.5 g/123.88g/mol

                                                    n = 0.07 moles


Step 4: 0.07 × 12 = 0.84 moles of fluorine.

Fluorine is diatomic gas so we multiplied the number of moles by 12.


Step 5: To find the mass of fluorine we multiply the number of moles with the molar mass.

                            Mass of fluorine = 0.84 ×  228 

                                                        = 191.52 grams.

4 0
3 years ago
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