Is na2o a element or compound

Even though so much energy is required to form a metal cation with a 2+ charge, the alkaline earth metals form halides with gene

nasty-shy [4]

The ∆Hrxn of the reaction is -394.5kJ/mol.

<h3>What is alkaline earth metal? </h3>

The alkaline earth metals are those elements which correspond to group 2 of the modern periodic table.

All elements of this group forms a cation of +2 charge.

The other elements of this group are:

Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium.

<h3>What is Halogen? </h3>

The Halogen elements are present in group 17 of the modern periodic table.

All elements of this groups forms anions of -1 charge.

The elements of this group are:

Fluorine, Chlorine, bromine, iodine, and astatine.

∆Hrxn = ∆H(bond broken) - ∆H(bond formed)

We have following data of bond energy in kJ/mol:

Mg—Mg = 738

Cl—Cl = -349

Mg—Cl = 783.5

Since, one mole of Mg react with one mole of Cl atom to form one mole of MgCl

∆Hrxn = 738-349-783.5

∆Hrxn = -394.5kJ/mol.

Thus, we concluded that the ∆Hrxn of the reaction is -394.5kJ/mol.

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3 0

2 years ago

What is the pH of a 0.640 M solution of C₅H₅NHBr (Kb of C₅H₅N is 1.7 × 10⁻⁹)?

Elden [556K]

The pH of a 0.64 M solution of pyridine (C₅H₅N) is 9.52.

A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline.

The equation for the protonation of the base pyridine is the following:

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻ (1)

Kb = 1.7 × 10⁻⁹ (Given)

To calculate the pH of the solution we need to use the following equation:

pH + pOH = 14

=14 - [-log[OH⁻]]

= 14 + log[OH⁻]

Now, we need to find the concentration of the OH⁻ ions. Since pyridine is a weak base, at the equilibrium we have (eq 1):

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻

0.64 - x x x

After entering the values of [C₅H₅N] = 0.64-x, [C₅H₅NH⁺] = x, and [OH⁻] = x, into equation (2) we can find the concentration of OH⁻:

1.7 × 10⁻⁹ =[C₅H₅NH⁺] [OH⁻] / [C₅H₅N]

= x . x / 0.64-x

1.7 × 10⁻⁹ (0.64-x) - x² = 0

Solving the above quadratic equation for x, we have :

x₁ = -3.32 x 10⁻⁵
x₂ = 3.32 x 10⁻⁵

Now, We can calculate the pH, after taking the positive value, x₂, (concentrations cannot be negative) and entering into above equation :

<em />

<em>pH = </em>14 + log[OH⁻]

= 14 + log (3.32 x 10⁻⁵)

= 9.52

Therefore, the pH of the solution of pyridine is 9.52.

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3 0

2 years ago

A monatomic ideal gas at a pressure of 1.00 atm expands adiabatically from an initial volume of 1.50 m3 to a final volume of 4.0

tamaranim1 [39]

The correct answer is 1atm.

<h3>What is Kinetic theory of gases?</h3>

A lot of the fundamental ideas of thermodynamics were established with the help of the kinetic theory of gases, a straightforward yet historically significant classical model of the thermodynamic behaviour of gases. According to the model, a gas is made up of numerous identical submicroscopic particles (atoms or molecules) that are all moving rapidly and randomly. It is considered that they are substantially smaller in size than the particle spacing on average. Random elastic collisions between the particles and with the container's walls occur between the particles. The simplest form of the model only takes into account the interactions within the ideal gas.

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7 0

2 years ago

What chemical reactions occur in a Nelson's cell?

Cerrena [4.2K]

Explanation:

The graphite anodes are suspended into the brine. During electrolysis, Cl ions are oxidized at the anode and chlorine gas goes out of the cell, while sodium ions are reduced at the mercury cathode forming sodium amalgam. ... Hydrogen gas is obtained as a by–product at the cathode.

8 0

1 year ago

What is the mass of 1.25 L of ammonia gas at STP

Alex73 [517]

Answer:

mass 1.25 Liters NH₃(gas) = 0.949 grams (3 sig-figs)

Explanation:

At STP (Standard Temperature-Pressure conditions => 0°C(=273K) and 1atm pressure, 1 mole <u>any</u> gas will occupy 22.4 Liters.

So, given 1.25 Liters ammonia gas at STP, convert to moles then multiply by formula wt. (17g/mole gives mass of NH₃.

moles NH₃(gas) = 1.25L NH₃(gas)/22.4L NH₄(gas)· NH₃(gas)mole⁻¹ = 0.0558 mole NH₃(gas).

Converting to grams NH₃(gas) = 0.0558 mole NH₃(gas) x 17 g·mol⁻¹ = 0.949 grams NH₃(gas).

7 0

3 years ago