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3 years ago

Determine the number of moles in 5.25x1024 formula units if lead (IV) oxide.

Chemistry

1 answer:

a_sh-v [17]3 years ago

6 0

Answer:

8.72 mol PbO₂

General Formulas and Concepts:

Chemistry - Atomic Structure

Using Dimensional Analysis
Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Explanation:

Step 1: Define

5.25 × 10²⁴ formula units PbO₂

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

$5.25 \cdot 10^{24} \ formula \ units \ PbO_2(\frac{1 \ mol \ PbO_2}{6.022 \cdot 10^{23} \ formula \ units \ PbO_2} )$ = 8.71803 mol PbO₂

Step 4: Check

We are given 3 sig figs. Follow sig fig rules and round.

8.71803 mol PbO₂ ≈ 8.72 mol PbO₂

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3 years ago

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Answer:

The metal has a molar mass of 65.37 g/mol

Explanation:

Step 1: Data given

Mass of the metal = 0.708 grams

Volume of hydrogen = 275 mL = 0.275 L

Atmospheric pressure = 1.0079 bar = 0.9947 atm

Temperature = 25°C

Vapor pressure of water at 25 °C = 0.03167 bar = 0.03126 atm

Step 2: The balanced equation

M(s) + H2SO4(aq) ⟶ MSO4 (aq) + H2(g)

Step 3: Calculate pH2

Atmospheric pressure = vapor pressure of water + pressure of H2

0.9947 atm = 0.03126 atm + pressure of H2

Pressure of H2 = 0.9947 - 0.03126

Pressure of H2 = 0.96344 atm

Step 4: Calculate moles of H2

p*V=n*R*T

⇒ with p = The pressure of H2 = 0.96344 atm

⇒ with V = the volume of H2 = 0.275 L

⇒ with n = the number of moles H2 = TO BE DETERMINED

⇒ with R = the gas constant = 0.08206 L*atm/K*mol

⇒ with T = the temperature = 25°C = 298 Kelvin

n = (p*V)/(R*T)

n = (0.96344 * 0.275)/(0.08206*298)

n = 0.01083 moles

Step 5: Calculate moles of M

For 1 mole of H2 produced, we need 1 mole M

For 0.0108 moles of H2 we need 0.01083 moles of M

Step 6: Calculate molar mass of M

Molar mass M = Mass M / moles M

Molar mass M = 0.708 grams / 0.01083 moles

Molar mass M = 65.37 g/mol

The metal has a molar mass of 65.37 g/mol

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4 years ago