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Nadya [2.5K]
3 years ago
15

What mass is in 5 moles of helium?

Chemistry
1 answer:
ArbitrLikvidat [17]3 years ago
3 0

Answer:

Mass = 20 g

Explanation:

Given data:

Number of moles of He = 5 mol

Mass of He = ?

Solution:

Formula:

Number of moles = mass/ molar mass

Molar mass = 4 g/mol

by putting values,

5 mol = Mass / 4 g/mol

Mass = 5 mol × 4 g/mol

Mass = 20 g

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can someone explain how this is wrong? I don’t think it is wrong but my chem teacher deducted points. so why?
ruslelena [56]

Answer: measure the mass (48.425g) of KCl

Explanation:

To prepare the solution 0.65M KCl we must measure the mass of KCl that would be dissolved in 1L of the solution. This can be achieved by:

Molar Mass of KCl = 39 + 35.5 = 74.5g/mol

Number of mole (n) = 0.65

Mass conc of KCl = n x molar Mass

Mass conc of KCl = 0.65 x 74.5 = 48.425g

Therefore, to make 0.65M KCl, we must measure 48.425g

7 0
3 years ago
Calculate the area of a 3.0 inch by 5.0 inch index card in square millimeters (mm). (You can look up the formula for the area of
meriva

Answer:

The area of the given rectangular index card = <u>9677.4 mm²</u>    

Explanation:

Area is defined as the space occupied by a two dimensional shape or object. The SI unit of area is square metre (m²).

<u>The area of a rectangle</u> (A) =  length (l) × width (w)

Given dimensions of the rectangle: Length (l) = 5.0 inch, Width (w) = 3.0 inch

Since, 1 inch = 25.4 millimetres (mm)

Therefore, l = 5 × 25.4 = 127 mm, and w = 3 × 25.4 = 76.2 mm

Therefore, <u>the area of the given rectangular index card</u> = A= l × w = 127 mm × 76.2 mm = <u>9677.4 mm²</u>

5 0
3 years ago
What happens when energy is released during atomic fission
Vesnalui [34]
Nuclear energy is called the energy obtained by the transformation of atomic nuclei, so small and heavy clusters of particles inside the atom. Nuclear energy can be produced in two ways, by cleavage or synthesis of nuclei. Heavy nuclei of radioactive elements such as uranium or plutonium, can be split into two nuclei. By splitting are released from the nucleus of neutrons that collide with other nuclei causing them to split and subsequent emission of neutrons. This is called a chain reaction. The condition calls self-sustaining nuclear reaction is slowing down neutrons. For this purpose, a special substance, called moderator. The neutrons collide with the molecules of the moderator precipitate heating speed while the moderator. The resulting heat heats the water so that a couple who drives a turbine generating electricity. Another way of producing nuclear energy is nuclear fusion, in which nuclei combine to light elements. So far, fusion, however, failed to carry out so that it can be applied to the economy as a source of energy.
4 0
3 years ago
The image shows two spheres hung from a thin rope. The spheres do not affect each other.
jekas [21]

Answer:

both spheres have a positive charge

8 0
3 years ago
Which is the correct formula for phosphorus pentachloride? PCl4 because a subscript of 4 indicates four Cl atoms PCl5 because a
Arlecino [84]

Answer: The correct formula for phosphorous pentachloride is PCl_5 because a subscript 5 indicates five chlorine (Cl) atoms.

Explanation: For the given molecule, phosphorous pentachloride, there are 2 atoms present which are phosphorous and chlorine atoms.

Number of phosphorous atoms = 1

Number of chlorine atoms = 5

So, the correct formula for phosphorous pentachloride will be PCl_5 because the subscript 5 represents the 5 chlorine atoms.

7 0
3 years ago
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