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2 years ago

How much 1.5 m sodium hydroxide is necessary to exactly neutralize 20.0 ml of 2.5 m phosphoric acid?

1 answer:

8 0

Answer is: 100 mL of sodium hydroxide.
Chemical reaction: 3NaOH + H₃PO₄ → Na₃PO₄ + 3H₂O.
V(H₃PO₄) = 20.0 mL ÷ 1000 mL/L = 0.02 L.
n(H₃PO₄) = V(H₃PO₄) · c(H₃PO₄).
n(H₃PO₄) = 0.02 L · 2.5 mol/L.
n(H₃PO₄) = 0.05 mol.
From chemical reaction: n(H₃PO₄) : n(NaOH) = 1 : 3.
n(NaOH) = 0.15 mol.
V(NaOH) = n(NaOH) ÷ c(NaOH).
V(NaOH) = 0.15 mol ÷ 1.5 mol/L.
V(NaOH) = 0.1 L · 1000 mL/L = 100 mL.

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An octet is formed via ionic bonding when one or more valence electrons are transferred from one atom to another.

An octet is formed via covalent bonding when valence electrons are shared between atoms.

An octet is always formed via ionic bonding

Explanation: The essence of bonding is stability. An octet or duplet state is formed when one or more valence electrons are shared. when the electrons are shared, the type of bond formed is a covalent bond. An octet is formed via ionic bonding when one or more valence electrons are transferred from one atom to another.

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2 years ago

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Zinc metal is added to hydrochloric acid to generate hydrogen gas and is collected over a liquid whose vapor pressure is the sam

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Question:

Zinc metal is added to hydrochloric acid to generate hydrogen gas and is collected over a liquid whose vapor pressure is the same as pure water at 20.0 degrees C (18 torr). The volume of the mixture is 1.7 L and its total pressure is 0.987 atm. Determine the number of moles of hydrogen gas present in the sample.

A. 0.272 mol

B. 0.04 mol

C. 0.997 mol

D. 0.139 mol

E. 0.0681 mol

Answer:

The correct option is;

E. 0.0681 mol

Explanation:

The equation for the reaction is

Zn + HCl = H₂ + ZnCl₂

Vapor pressure of the liquid = 18 torr = 2399.803 Pa

Total pressure of gas mixture H₂ + liquid vapor = 0.987 atm

= 100007.775 Pa

Therefore, by Avogadro's law, pressure of the hydrogen gas is given by the following equation

Pressure of H₂ = 100007.775 Pa - 2399.803 Pa = 97607.972 Pa

Volume of H₂ = 1.7 L = 0.0017 m³

Temperature = 20 °C = 293.15 K

Therefore,

$n = \frac{PV}{RT} = \frac{100007.775 \times 0.0017 }{8.3145 \times 293.15} = 0.068078 \ moles$

Therefore, the number of moles of hydrogen gas present in the sample is n ≈ 0.0681 moles.

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2 years ago

SEP Use Models Why does the number of electrons in each principal energy shell increase as the number of the shell increases?

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Answer:

See explanation

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The number of electrons in each principal energy shell increases as the number of shells increases because more electronic orbitals become available to accommodate the electrons.

For instance, the n= 2 level only accommodates eight electrons in the s and p orbitals whereas the n=3 level accommodates 18 electrons in s, p and d orbitals respectively.

Each principal level accommodates 2n^2 electrons where n= the principal energy shell.

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1 year ago

Calculate the wavelength of the photon emitted when an electron makes a transition from n=6 to n=3. You can make use of the foll

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Answer: The wavelength of light is $1.094\times 10^{-6}m$

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Putting the values in above equation, we get:

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2 years ago

An aluminum ion has a charge of +3, and an oxide has a charge of -2. What would be the product of a reaction between these two e

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