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3 years ago

What mass of natural gas (ch4) must you burn to emit 272 kj of heat?

1 answer:

7 0

CH4 + 2 O2 ---> CO2 + 2 H2O Q = 891,6 kJ / mol CH4

1 mol CH4 = 16 g

16 g ---- 891,6 kJ
x g ----- 272 kJ

x = 272 kJ × 16 g / 891,6 kJ = 4,88 g

You must burn 4,88 g of CH4.

:-) ;-)

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Calculate E ° for the half‑reaction, AgCl ( s ) + e − − ⇀ ↽ − Ag ( s ) + Cl − ( aq ) given that the solubility product constant

antoniya [11.8K]

Answer: The value of $E^{o}$ for the half-cell reaction is 0.222 V.

Explanation:

Equation for solubility equilibrium is as follows.

$AgCl(s) \rightleftharpoons Ag^{+}(aq) + Cl^{-}(aq)$

Its solubility product will be as follows.

$K_{sp} = [Ag^{+}][Cl^{-}]$

Cell reaction for this equation is as follows.

$Ag(s)| AgCl(s)|Cl^{-}(0.1 M)|| Ag^{+}(1.0 M)| Ag(s)$

Reduction half-reaction: $Ag^{+} + 1e^{-} \rightarrow Ag(s)$ , $E^{o}_{Ag^{+}/Ag} = 0.799 V$

Oxidation half-reaction: $Ag(s) + Cl^{-}(aq) \rightarrow AgCl(s) + 1e^{-}$ , $E^{o}_{AgCl/Ag}$ = ?

Cell reaction: $Ag^{+}(aq) + Cl^{-}(aq) \rightarrow AgCl(s)$

So, for this cell reaction the number of moles of electrons transferred are n = 1.

Solubility product, $K_{sp} = [Ag^{+}][Cl^{-}]$

= $1.77 \times 10^{-10}$

Therefore, according to the Nernst equation

$E_{cell} = E^{o}_{cell} - \frac{0.0592 V}{n} log \frac{[AgCl]}{[Ag^{+}][Cl^{-}]}$

At equilibrium, $E_{cell}$ = 0.00 V

Putting the given values into the above formula as follows.

$E_{cell} = E^{o}_{cell} - \frac{0.0592 V}{n} log \frac{[AgCl]}{[Ag^{+}][Cl^{-}]}$

$0.00 = E^{o}_{cell} - \frac{0.0592 V}{1} log \frac{1}{[Ag^{+}][Cl^{-}]}$

$E^{o}_{cell} = \frac{0.0592}{1} log \frac{1}{K_{sp}}$

= $0.0591 V \times log \frac{1}{1.77 \times 10^{-10}}$

= 0.577 V

Hence, we will calculate the standard cell potential as follows.

$E^{o}_{cell} = E^{o}_{cathode} - E^{o}_{anode}$

$0.577 V = E^{o}_{Ag^{+}/Ag} - E^{o}_{AgCl/Ag}$

$0.577 V = 0.799 V - E^{o}_{AgCl/Ag}$

$E^{o}_{AgCl/Ag}$ = 0.222 V

Thus, we can conclude that value of $E^{o}$ for the half-cell reaction is 0.222 V.

3 0

3 years ago

How many different substituents are required on a carbon atom for it to be chiral?

zheka24 [161]

Four different substituents are required on a carbon atom for it to be chiral.

<h3>What is Chiral Carbons ?</h3>

The carbon atom which is attached with four different types of group of atoms or atoms is called Chiral carbon. Chiral molecules are non superimposable on their mirror images. Chiral carbon is also called asymmetric carbon.

Example:

$Br - \underset{H} {\underset{|} {\overset{CH_3} {\overset{|}{C}}}} - Cl$

In the above example we can see that carbon atom has 4 different group attached with it that is Br, Cl, H, CH₃.

Thus from the above conclusion we can say that Four different substituents are required on a carbon atom for it to be chiral.

Learn more about the Chiral carbon here: brainly.com/question/1195366

#SPJ4

6 0

2 years ago

Calculate the ph of 0,24 m of kch3coo.?

Galina-37 [17]

Answer:

Correct option is A)

KaC

1.8×10

−6

=1.34×10

−3

pH=−log[H

]

=2.88

Explanation:

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6 0

3 years ago

Suppose that 6.2 mL of 2.1 M KOH(aq) is transferred to a 250 mL volumetric flask and diluted to the mark. It was found that 36.9

galina1969 [7]

Answer:

0.928 M

Explanation:

The concentration of acid can be determined by using the volume used and the concentration and volume used of base.

We will use the law of equivalence of moles.

M₁V₁=M₂V₂

M₁ = concentration of base used

V₁ = volume of base used

M₂ = concentration of acid used =? (to be determined)

V₂ = volume of acid used

The initial concentration of KOH used is diluted so let us find the final concentration of KOH after dilution

initial moles = final moles

initial concentration X initial volume = final concentration X final volume

6.2 X 2.1 = 250 X final concentration

final concentration = 0.052 M = M₁

V₁ = 36.9 mL

V₂ = 6.2 mL

Here with each mole of phosphoric acid three moles of KOH are used.

Therefore

3 M₁V₁ = M₂V₂

M₂ = $\frac{V_{2}}{3M_{1}V_{1}}=0.928M$

3 0

3 years ago

The__ model assigns to fixed orbits of defined energy. To move between orbits, electrons must emit or absorb _____ radiation

AURORKA [14]

Answer:

The Bohr model assigns to fixed orbits of defined energy. To move between orbits, electrons must emit or absorb electromagnetic radiation

Explanation:

In the Bohr model of the atom, the atom itself looks like a solar system.

In fact, at the center of the atom we have the nucleus, which contains protons and neutrons.

Around the nucleus, at a much higher distance, we have the electrons, negatively charged. The electrons move around the nucleus in fixed orbits, like the planets around the Sun.

According to Bohr's model, the electrons cannot live in the space between two orbits, but they must stay in one of these orbits. Each of these orbits is associated to a certain energy level: therefore, this means that the energies of the electrons in an atom are quantized, so they cannot take all possible values, but only some precise values.

Moreover, according to the law of conservation of energy:

- When an electron jumps from a lower energy level to a higher energy level, it must absorbs energy, and this energy is absorbed in the form of electromagnetic radiation (a photon) whose energy is equal to the difference in energy between the two levels

- SImilarly, when an electron jumps from a higher energy level to a lower energy level, it releases energy, in the form of electromagnetic radiation (a photon) whose energy is equal to the difference in energy between the two levels.

4 0

3 years ago