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Molodets [167]
3 years ago
11

Which substance is used to remove rust from metal?

Physics
2 answers:
Vlad [161]3 years ago
7 0

Answer : The correct option is, (B) Hydrochloric acid(HCl)

Explanation :

Rust is an iron oxide, which is formed by the reaction of iron with oxygen in the presence of water.

As we know that the rust is an iron oxide (base) which is removed by an acid.

As per given options, the acid used to remove the rust from the metal is hydrochloric acid and not sulfuric acid because sulfuric acid is an oxidizing agent which oxidizes the metal more.

While the other options, ammonia and sodium hydroxide are a base.

Hence, hydrochloric acid is used to remove rust from metal.

Andreyy893 years ago
3 0
Hydrochloric acid would be the correct answer 

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An ocean thermal energy conversion system is being proposed for electric power generation. Such a system is based on the standar
defon

Answer:

Explanation:

Dear Student, this question is incomplete, and to attempt this question, we have attached the complete copy of the question in the image below. Please, Kindly refer to it when going through the solution to the question.

To objective is to find the:

(i) required heat exchanger area.

(ii) flow rate to be maintained in the evaporator.

Given that:

water temperature = 300 K

At a reasonable depth, the water is cold and its temperature = 280 K

The power output W = 2 MW

Efficiency \zeta = 3%

where;

\zeta = \dfrac{W_{out}}{Q_{supplied }}

Q_{supplied } = \dfrac{2}{0.03} \ MW

Q_{supplied } = 66.66 \ MW

However, from the evaporator, the heat transfer Q can be determined by using the formula:

Q = UA(L MTD)

where;

LMTD = \dfrac{\Delta T_1 - \Delta T_2}{In (\dfrac{\Delta T_1}{\Delta T_2} )}

Also;

\Delta T_1 = T_{h_{in}}- T_{c_{out}} \\ \\ \Delta T_1 = 300 -290 \\ \\ \Delta T_1 = 10 \ K

\Delta T_2 = T_{h_{in}}- T_{c_{out}} \\ \\ \Delta T_2 = 292 -290 \\ \\ \Delta T_2 = 2\ K

LMTD = \dfrac{10 -2}{In (\dfrac{10}{2} )}

LMTD = \dfrac{8}{In (5)}

LMTD = 4.97

Thus, the required heat exchanger area A is calculated by using the formula:

Q_H = UA (LMTD)

where;

U = overall heat coefficient given as 1200 W/m².K

66.667 \times 10^6 = 1200 \times A \times 4.97 \\ \\  A= \dfrac{66.667 \times 10^6}{1200 \times 4.97} \\ \\  \mathbf{A = 11178.236 \ m^2}

The mass flow rate:

Q_{H} = mC_p(T_{in} -T_{out} )  \\ \\  66.667 \times 10^6= m \times 4.18 (300 -292) \\ \\ m = \dfrac{  66.667 \times 10^6}{4.18 \times 8} \\ \\  \mathbf{m = 1993630.383 \ kg/s}

3 0
3 years ago
What is the velocity (m/s) after 5 seconds of fall
gregori [183]
5 second fall starting at 0 m/s
ball strikes ground at a speed = 49 meters per second.
3 0
3 years ago
If a farsighted person has a near point that is 0.600 mm from the eye, what is the focal length f2f2f_2 of the contact lenses th
Readme [11.4K]

Answer:

0.22mm

Explanation:

A far sighted person is a person suffering from long sightedness i.e such individual can only see far distant object clearly but not near distant object. The defect is corrected using convex lens.

Since convex lens is used, the focal (f) length of the lens is positive and the image distance (v) is also positive.

Using the lens formula,

1/f = 1/u + 1/v

Where u is the object distance = 0.35mm

v = 0.6mm

1/f = 1/0.35+1/0.6

1/f = 2.86 + 1.67

1/f = 4.53

f = 1/4.53

f = 0.22mm

The focal length of the contact lenses will be 0.22mm

5 0
3 years ago
Why do nonmetals have a negative oxidation number
galina1969 [7]
Oxygen has<span> a higher electro negativity that then Sulfur, so Sulfur </span>will<span> " lose" electrons to Oxygen and that </span>is<span> the electrons </span>will be<span> pulled closer to the Oxygen causing, for oxygen to </span>have a negative<span> charge and the Sulfur to </span>have<span> a positive charge</span>
8 0
3 years ago
What is the formula of the compound between calcium and sulfur that has the percent composition 55.6?
Yanka [14]

CaS is the empirical formula of the compound between calcium and sulphur that has the percent composition 55.6.

When percentages are given, we take a total mass of 100 grams.

Therefore the mass of each element is equal to the percentage given.

Mass of Ca = 55.6 g (given) of

S Mass = 44.4 g (100 - 55.6 = 44.4)

Step 1: Convert the given mass to moles.

moles Ca = given mass Ca / molar mass Ca

moles = 55.6 / 40 = 1.39 moles

mol S = specific mass S / molar mass S

mol = 44.4 / 32 = 1.39 mol

Step 2: Divide the molar ratio of each molar value by the smallest number of moles calculated.

For Ca = 1.39 / 1.39 = 1

For S = 1.39 / 1.39 = 1

The ratio of Ca : S = 1:1

Hence the empirical formula of the given compound will be CaS.

Learn more about empirical formula here : brainly.com/question/1496676

#SPJ4

8 0
1 year ago
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