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Naddik [55]
4 years ago
14

What is an indicator?

Chemistry
1 answer:
Anna [14]4 years ago
7 0

a thing, especially a trend or fact, that indicates the state or level of something.

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Ideal gas (n 2.388 moles) is heated at constant volume from T1 299.5 K to final temperature T2 369.5 K. Calculate the work and h
bija089 [108]

Answer : The work, heat during the process and the change of entropy of the gas are, 0 J, 3333.003 J and -10 J respectively.

Explanation :

(a) At constant volume condition the entropy change of the gas is:

\Delta S=-n\times C_v\ln \frac{T_2}{T_1}

We know that,

The relation between the C_p\text{ and }C_v for an ideal gas are :

C_p-C_v=R

As we are given :

C_p=28.253J/K.mole

28.253J/K.mole-C_v=8.314J/K.mole

C_v=19.939J/K.mole

Now we have to calculate the entropy change of the gas.

\Delta S=-n\times C_v\ln \frac{T_2}{T_1}

\Delta S=-2.388\times 19.939J/K.mole\ln \frac{369.5K}{299.5K}=-10J

(b) As we know that, the work done for isochoric (constant volume) is equal to zero. (w=-pdV)

(C) Heat during the process will be,

q=n\times C_v\times (T_2-T_1)=2.388mole\times 19.939J/K.mole\times (369.5-299.5)K= 3333.003J

Therefore, the work, heat during the process and the change of entropy of the gas are, 0 J, 3333.003 J and -10 J respectively.

7 0
3 years ago
Why is the atomic radius of iodine greater than the atomic radius of fluorine?
Artist 52 [7]

Answer:

Iodine has more electron levels (rings) than fluorine.

Explanation:

On the periodic table,  fluorine is on period 2 so it has 2 outer rings, iodine is on period 5 so it has 5 outer rings. The more rings the higher radius.

7 0
3 years ago
Which of the following is true regarding acids and bases?
fredd [130]

Both acids and bases cause indicator dyes to change colors.

3 0
4 years ago
A certain weak acid, HA, has a Ka value of 6.7 X 10^-7.
yuradex [85]

Answer:

  • <u>Part A: 0.26% </u>

  • <u>Part B: 0.82%</u>

Explanation:

<em>Percent ionization</em> is the percent of the original acid that has ionized:

  • %, ionization = (molar concentration of hydrogen ions at equilibrium / molar concentration of original acid) × 100

<u><em>Part A:</em></u>

<u>1) Data:</u>

  • Ka: 6.7 × 10 ⁻⁷
  • [HA] = 0.10 M
  • %, ionization = ?

<u>2) Equilibrium equation:</u>

  • HA ⇄ H⁺ + A⁻

<u>3) ICE (initial, change, equilbirium) table </u>

                           Concentrations

                         HA            H⁺       A⁻

Initial                 0.10           0        0

Change             - x            + x     + x

Equilibrium     0.10 - x         x         x

  • Equation:      Ka          =         [H⁺] [A⁻] / [HA] =

                        6.7 × 10 ⁻⁷   =          x² / (0.10 - x)

<u>4) Solve the equation:</u>

Since Ka << 1, you can assume x << 0.10 and 0.10 - x ≈ 0.10

  • 6.7 × 10 ⁻⁷ ≈  x² / 0.10 ⇒ x² ≈ 6.7 × 10⁻⁸ ⇒ x ≈ 2.588 × 10⁻⁴

  • [H⁺] ≈ 2.588 × 10⁻⁴ M

  • % ionization ≈ (2.588 × 10⁻⁴ M / 0.1 M) × 100 ≈ 0.2588 % ≈ 0.26% (two significant figures)

<u><em>Part B:</em></u>

<u>1) Data:</u>

  • Ka: 6.7 × 10 ⁻⁷
  • [HA] = 0.010 M
  • %, ionization = ?

<u>2) Equilibrium equation:</u>

  • HA ⇄ H⁺ + A⁻

<u>3) ICE table:</u>

                            Concentrations

                           HA              H⁺       A⁻

Initial                 0.010            0         0

Change               - x              + x     + x

Equilibrium     0.010 - x           x         x

  • Equation:      Ka          =         [H⁺] [A⁻] / [HA] =

                        6.7 × 10 ⁻⁷   =          x² / (0.010 - x)

<u>4) Solve the equation</u>:

Since Ka << 1, you can assume x << 0.010 and 0.010 - x ≈ 0.010

  • 6.7 × 10 ⁻⁷ ≈  x² / 0.010 ⇒ x² ≈ 6.7 × 10⁻⁹ ⇒ x ≈ 8.185 × 10⁻5

  • [H⁺] ≈ 8.185 × 10⁻⁵ M

  • % ionization ≈ (8.185 × 10⁻⁵ M / 0.010 M) × 100 ≈ 0.8185 % ≈ 0.82% (two significant figures)
4 0
4 years ago
Which of the following would be a clue that a rock is metamorphic?
sladkih [1.3K]
This answer would be B
3 0
3 years ago
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