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tekilochka [14]
2 years ago
9

How many moles are 4.20 * 10 ^ 25 atoms of Ca?

Chemistry
1 answer:
aleksandr82 [10.1K]2 years ago
4 0

Answer:

~69.744 moles of Ca

Explanation:

Using Avogadro's constant , we know that:

1 mole = 6.022 x 10^23 atoms

S0, the number of moles in 4.20 x 10^25 atoms of Ca:

=(4.20 x 10^25 x 1 )/(6.022 x 10^23)

~69.744 moles of Ca

Q2:How many atoms are in 0.35 moles of oxygen?

1 mole = 6.022 x 10^23 atoms

S0, the number of atoms in 0.35 moles of  oxygen:

=[0.35 x (6.022 x 10^23)]

=2.1077 x 10^23 atoms of Oxygen

Hope it helps:)

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Explanation:

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Salt is often added to water to raise the boiling point to heat food more quickly. if you add 30.0g of salt to 3.75kg of water,
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Assuming an ebullioscopic constant of 0.512 °C/m for the water, If you add 30.0g of salt to 3.75kg of water, the boiling-point elevation will be 0.140 °C and the boiling-point of the solution will be 100.14 °C.

<h3>What is the boiling-point elevation?</h3>

Boiling-point elevation describes the phenomenon that the boiling point of a liquid will be higher when another compound is added, meaning that a solution has a higher boiling point than a pure solvent.

  • Step 1: Calculate the molality of the solution.

We will use the definition of molality.

b = mass solute / molar mass solute × kg solvent

b = 30.0 g / (58.44 g/mol) × 3.75 kg = 0.137 m

  • Step 2: Calculate the boiling-point elevation.

We will use the following expression.

ΔT = Kb × m × i

ΔT = 0.512 °C/m × 0.137 m × 2 = 0.140 °C

where

  • ΔT is the boiling-point elevation
  • Kb is the ebullioscopic constant.
  • b is the molality.
  • i is the Van't Hoff factor (i = 2 for NaCl).

The normal boiling-point for water is 100 °C. The boiling-point of the solution will be:

100 °C + 0.140 °C = 100.14 °C

Assuming an ebullioscopic constant of 0.512 °C/m for the water, If you add 30.0g of salt to 3.75kg of water, the boiling-point elevation will be 0.140 °C and the boiling-point of the solution will be 100.14 °C.

Learn more about boiling-point elevation here: brainly.com/question/4206205

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solubility of salt at 10 degree Celsius is 20 how does it what does it means what happens if the temperature of saturated solution is increased

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