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2 years ago

Calculate each of the following quantities:

1 answer:

5 0

The number of moles in 78.9 g of sodium perchlorate is 0.644 moles and 3.876 x 10²³ formula units are particles.

<h3>What are formula units?</h3>

Moles are converted to formula units by multiplying them by 6.02 x 1023, or Avogadro's number (Na). The moles and masses of tiny particles are estimated using this method.

Given that the mass of sodium perchlorate is 78.9 g

The molar mass of sodium perchlorate is 122.44 g/mol

Moles of sodium perchlorate will be

Moles (n) = mass ÷ molar mass

n = 78.9 g ÷ 122.44

n = 0.644 moles

If 1 mole = 6.02 x 10²³

Then, 0.644 moles = 3.876 x 10²³ particles

Thus, there are 0.644 moles of sodium perchlorate in 78.9 g.

Learn more about formula units, here:

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72.0 grams of water how many miles of sodium with react with it?

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Answer:

$\large \boxed{\text{8.00 mol}}$

Explanation:

We will need a balanced chemical equation with masses, moles, and molar masses.

1. Gather all the information in one place:

Mᵣ: 18.02

2Na + H₂O ⟶ 2NaOH + H₂

m/g: 72.0

2. Moles of H₂O

$\text{Moles of H$_{2}$O} = \text{72.0 g H$_{2}$O} \times \dfrac{\text{1 mol H$_{2}$O}}{\text{18.02 g H$_{2}$O}} = \text{3.996 mol H$_{2}$O}$

3. Moles of Na

The molar ratio is 2 mol Na/1 mol H₂O.

$\text{Moles of Na} = \text{3.996 mol H$_{2}$O} \times \dfrac{\text{2 mol Na}}{\text{1 mol H$_{2}$O}} = \textbf{8.00 mol Na}\\\\\text{The water will react with $\large \boxed{\textbf{ 8.00 mol}}$ of Na}$

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3 years ago

Given the following information:

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Answer:

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Explanation:

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2 years ago

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Raoult's law states that the vapor pressure of a solvent above a solution is equal to the vapor pressure of the pure solvent at the same temperature scaled by the mole fraction of the solvent present: Psolution=χsolventPosolvent.

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3 years ago

Which of the following molecules would you expect to have a dipole moment of zero? a,CH2 Ch3

Vadim26 [7]

Answer: The molecule $CH_{3}-CH_{3}$ is expected to have a dipole moment of zero.

Explanation:

The product of magnitude of the charge calculated in electrostatic units is called dipole moment.

Formula for dipole moment is as follows.

Dipole moment = Charge (in esu) $\times$ distance (in cm)

Non-polar molecules have zero dipole moment.

For example, $CH_{3}-CH_{3}$ is a non-polar molecule so its dipole moment is zero.

$H_{2}C=O$ is a polar molecule so it will have dipole moment.

$CH_{2}Cl_{2}$ is a polar molecule so it will have dipole moment.

$NH_{3}$ has nitrogen atom as more electronegative than hydrogen atom. So, net dipole moment will be in the direction of nitrogen atom.

Thus, we can conclude that the molecule $CH_{3}-CH_{3}$ is expected to have a dipole moment of zero.

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3 years ago

2NH4Cl(s)+Ba(OH)2⋅8H2O(s)→2NH3(aq)+BaCl2(aq)+10H2O(l) The ΔH for this reaction is 54.8 kJ . How much energy would be absorbed if

irakobra [83]

1) Chemical equation

<span>2NH4Cl(s)+Ba(OH)2⋅8H2O(s)→2NH3(aq)+BaCl2(aq)+10H2O(l)

2) Stoichiometric ratios

2 mol NH4Cl(s) : 54.8 KJ

3) Convert 24.7 g of NH4Cl into number of moles, using the molar mass

molar mass of NH4Cl = 14 g/mol + 4*1 g/mol + 35.5 g/mol = 53.5 g/mol

number of moles = mass in grams / molar mass

number of moles = 24.7 g / 53.5 g/mol = 0.462 moles

4) Use proportions:

2 moles NH4Cl / 54.8 kJ = 0.462 moles / x

=> x = 0.462 moles * 54.8 kJ / 2 moles = 12.7 kJ

Answer: 12.7 kJ
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3 years ago