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3 years ago

Which property of a substance can be determined using a pH indicator?

Chemistry

2 answers:

satela [25.4K]3 years ago

7 0

Answer:A. Acidity

Explanation:

A pH value is determined from the negative logarithm of this concentration and is used to indicate the acidic,basic or neutral character of the substance you are testing

Amanda [17]3 years ago

6 0

Answer:b

Exbplanation:

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Argon gas has a boiling point of -197 °C. Which of the following diagrams best represents the

Paha777 [63]

Answer:

(a)

Explanation:

Hello,

In this case, the temperature required to boil argon, it means, transform it from liquid to gas is -197 °C. In such a way, since the temperature inside the steel sphere is -190 °C, which is greater than the boiling point, we realize argon is gaseous, therefore, the molecules will be spread inside the sphere as they will be moving based on the kinetic theory of gases.

For that reason, answer is scheme (a).

Best regards.

6 0

3 years ago

Determine the pH of the resulting solution if 25 mL of 0.400 M strychnine (C21H22N2O2) is added to 50 mL of 0.200 M HCl? Assume

DIA [1.3K]

Answer:

pH = 4.56

Explanation:

The strychnine reacts with HCl as follows:

C₂₁H₂₂N₂O₂ + HCl ⇄ C₂₁H₂₂N₂O₂H⁺ + Cl⁻

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For strychnine buffer:

pOH = 5.74 + log [C₂₁H₂₂N₂O₂H⁺] / [C₂₁H₂₂N₂O₂]

Initial moles of C₂₁H₂₂N₂O₂ are:

0.025L * (0.400 mol / L) = 0.01 moles C₂₁H₂₂N₂O₂

And of HCl are:

0.05L * (0.200 mol / L) = 0.01 moles HCl

That means after the reaction, you will have just 0.01 moles of C₂₁H₂₂N₂O₂H⁺ in 50mL + 25mL = 0.075L. And molarity is:

[C₂₁H₂₂N₂O₂H⁺] = 0.01 mol / 0.075L = 0.1333M

This conjugate acid, is in equilibrium with water as follows:

C₂₁H₂₂N₂O₂H⁺(aq) + H₂O(l) ⇄ C₂₁H₂₂N₂O₂ + H₃O⁺

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<em>Where Ka = Kw / Kb = 1x10⁻¹⁴ / 1.8x10⁻⁶ = 5.556x10⁻⁹</em>

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Ka is defined as:

Ka = 5.556x10⁻⁹ = [C₂₁H₂₂N₂O₂] [H₃O⁺] / [C₂₁H₂₂N₂O₂H⁺]

In equilibrium, concentrations are:

C₂₁H₂₂N₂O₂ = X

H₃O⁺ = X

C₂₁H₂₂N₂O₂H⁺ = 0.1333M - X

Replacing in Ka expression:

5.556x10⁻⁹ = [X] [X] / [0.1333M - X]

7.39x10⁻¹⁰ - 5.556x10⁻⁹X = X²

7.39x10⁻¹⁰ - 5.556x10⁻⁹X - X² = 0

Solving for X:

X = - 2.72x10⁻⁵M → False solution. There is no negative concentrations

X = 2.72x10⁻⁵M → Right solution.

As H₃O⁺ = X

H₃O⁺ = 2.72x10⁻⁵M

And pH = -log H₃O⁺

4 0

3 years ago

Find the number of moles of in 571,0 g of tetraphosphorous octoxide.

mars1129 [50]

Answer:

Think sorry if i did it wrong The molar mass that is the mass of 6.022 X 1023 atoms of helium is 4g. Hence 1 mole of He = 4 g of He = 6.022 X 1023atoms of He. 1 g of He = (6.022 X 1023) / 4 atoms of He. 52 g of He = (6.022 X 1023X 52 ) / 4 atoms of He.

For Helium,

Number of atoms=Number of moles ×6.022×1023

No of Moles = 6.022×10

2312.044×10

23 = 2.

Now, atomic mass of He=4

Weight = 2×4 = 8 g

The molar mass that is the mass of 6.022 X 1023 atoms of helium is 4g. Hence 1 mole of He = 4 g of He = 6.022 X 1023atoms of He. 1 g of He = (6.022 X 1023) / 4 atoms of He. 52 g of He = (6.022 X 1023X 52 ) / 4 atoms of He.

As we know, gram atoms = gram mole

here, no of moles = 23/46 =2 so no of gram atoms are 2.

Explanation:

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3 years ago

Which statement correctly describes protons and neutrons? *

Andrei [34K]

Answer:

They have the same mass but different electrical charges.

Explanation:

Protons have a positive charge while neutrons have a neutral charge. Although they have different charges, they have the same amount of mass.

6 0

2 years ago

Read 2 more answers

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Allisa [31]

Answer:

12.5

1.95x10^-10

1.5

0.5

in that order

Explanation:

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3 years ago