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laiz [17]
2 years ago
9

Mass of 2×10^21 number of atoms of an element is 0.4g. What is the mass of 0.5 mole of the element?

Chemistry
1 answer:
alexandr402 [8]2 years ago
5 0

Answer:

66.7 g

Explanation:

Number of atoms = 2×10²¹

Mass of 2×10²¹ atoms = 0.4 g

Mass of 0.5 moles of that element = ?

Solution:

1 mole contain 6.022×10²³ atoms

2×10²¹ atoms × 1 mol / 6.022×10²³ atoms

0.33×10⁻² mol

0.003 mol

 0.003 mole have mass of 0.4 g

0.5 mol have mass 0.5/0.003×0.4 g = 66.7 g

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andrezito [222]
I think the answer is 82.5
5 0
3 years ago
A compound is found to be 30.45% n and 69.55 % o by mass. if 1.63 g of this compound occupy 389 ml at 0.00°c and 775 mm hg, what
Charra [1.4K]
1) mass composition

N: 30.45%
O: 69.55%
   -----------
   100.00%

2) molar composition

Divide each element by its atomic mass

N: 30.45 / 14.00 = 2.175 mol

O: 69.55 / 16.00 = 4.346875

4) Find the smallest molar proportion

Divide both by the smaller number

N: 2.175 / 2.175 = 1

O: 4.346875 / 2.175 = 1.999 = 2

5) Empirical formula: NO2

6) mass of the empirical formula

14.00 + 2 * 16.00 = 46.00 g

7) Find the number of moles of the gas using the equation pV = nRT

=> n = pV / RT = (775/760) atm * 0.389 l / (0.0821 atm*l /K*mol * 273.15K)

=> n = 0.01769 moles

8) Find molar mass

molar mass = mass in grams / number of moles = 1.63 g / 0.01769 mol = 92.14 g / mol

9) Find how many times the mass of the empirical formula is contained in the molar mass

92.14 / 46.00 = 2.00

10) Multiply the subscripts of the empirical formula by the number found in the previous step

=> N2O4

Answer: N2O4
3 0
3 years ago
How do you find the molecular formula for a compound
HACTEHA [7]
<span>Start with the number of grams of each element, given in the problem.Convert the mass of each element to moles using the molar mass from the periodic table.Divide each mole value by the smallest number of moles calculated.<span>Round to the nearest whole number.</span></span>
5 0
3 years ago
What inference can be drawn from the graph?
defon

Answer:

i think its C

Explanation:

7 0
2 years ago
Convert 675 nanograms to milligrams.
STALIN [3.7K]

675 nanograms is equivalent to 6.75 × 10-⁴ milligrams.

<h3>How to convert nanograms to milligrams?</h3>

Nanograms is a unit of mass equal to 0.000000001 grams and has a symbol of ng.

On the other hand, milligrams is another unit of mass equal to 0.001grams and has a symbol of mg.

Nanograms and milligrams are both units of mass and can be inter-convertible as follows:

1 nanogram = 1 × 10-⁶ milligram

According to this question, 675 nanograms is equivalent to 675 × 10-⁶ milligrams.

Therefore, 675 nanograms is equivalent to 6.75 × 10-⁴ milligrams.

Learn more about milligrams at: brainly.com/question/20320382

#SPJ1

7 0
2 years ago
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