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2 years ago

7 on the pH scale represents what?

Chemistry

1 answer:

Nitella [24]2 years ago

3 0

Answer:

seven on the ph scale is the neutral point

Explanation:

The range goes from 0 - 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base. pH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water.

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In addition to the two types of motion found in liquids, gases have <br> What kind of motion

makvit [3.9K]

Answer:

In liquids, particles are quite close together and move with random motion throughout the container. Particles move rapidly in all directions but collide with each other more frequently than in gases due to shorter distances between particles.

3 0

3 years ago

Hydrochloric acid and sodium hydroxide are mixed together to form salt and water. During the reaction, the temperature of the so

sammy [17]

The best answer among the choices is option D. New substances are being formed will best explain that this process is a chemical change. Although, it cannot be seen directly we knew that an acid and base will undergo neutralization reaction forming a salt and water. The heat given off by the reaction can be a parameter however it does not only happens for reactions. It can also happen when dissolving substances.

6 0

3 years ago

A titration of 25.0 mL of a solution of the weak base aniline, C6H5NH2, requires 25.67 mL of 0.175 M HCl to reach the equivalenc

Lorico [155]

Answer:

a. 0.180M of C₆H₅NH₂

b. 0.0887M C₆H₅NH₃⁺

c. pH = 2.83

Explanation:

a. Based in the chemical equation:

C₆H₅NH₂(aq) + HCl(aq) → C₆H₅NH₃⁺(aq) + Cl⁻(aq)

<em>1 mole of aniline reacts per mole of HCl</em>

Moles required to reach equivalence point are:

Moles HCl = 0.02567L ₓ (0.175mol / L) = 4.492x10⁻³ moles HCl = moles C₆H₅NH₂

As the original solution had a volume of 25.0mL = 0.0250L:

4.492x10⁻³ moles C₆H₅NH₂ / 0.0250L = 0.180M of C₆H₅NH₂

b. At equivalence point, moles of C₆H₅NH₃⁺ are equal to initial moles of C₆H₅NH₂, that is 4.492x10⁻³ moles

But now, volume is 25.0mL + 25.67mL = 50.67mL = 0.05067L. Thus, molar concentration of C₆H₅NH₃⁺ is:

[C₆H₅NH₃⁺] = 4.492x10⁻³ moles / 0.05067L = 0.0887M C₆H₅NH₃⁺

c. At equivalence point you have just 0.0887M C₆H₅NH₃⁺ in solution. C₆H₅NH₃⁺ has as equilibrium in water:

C₆H₅NH₃⁺(aq) + H₂O(l) → C₆H₅NH₂ + H₃O⁺

Where Ka = Kw / Kb = 1x10⁻¹⁴ / 4.0x10⁻¹⁰ =

When the system reaches equilibrium, molar concentrations are:

[C₆H₅NH₃⁺] = 0.0887M - X

[C₆H₅NH₂] = X

[H₃O⁺] = X

Replacing in Ka formula:

2.5x10⁻⁵ = [X] [X] / [0.0887M - X]

2.2175x10⁻⁶ - 2.5x10⁻⁵X = X²

0 = X² + 2.5x10⁻⁵X - 2.2175x10⁻⁶

Solving for X:

X = -0.0015 → False solution. There is no negative concentrations.

X = 0.001477 → Right solution.

As [H₃O⁺] = X, [H₃O⁺] = 0.001477

Knowing pH = -log [H₃O⁺]

pH = -log 0.001477

7 0

3 years ago

A sample of gas has a mass of 0.560 g . Its volume is 125 mL at a temperature of 85 ∘C and a pressure of 757 mmHg .

-BARSIC- [3]

Answer:

132g/mole

Explanation:

using the formula PV=nRT should be used to solve for the number of moles (n). R is a constant which is 62.3637 L mmHG/mole K.

Inorder for your units to match you will have to convert 125ml to .125L and the temperature of 85C to K . you do that by adding 273 to the 85C and get 358K. Once you solve for n then you use that number and divide by the number of grams from the question (.560g) since molar mass is grams/moles.

4 0

3 years ago

My barometer is reading 1253 torr. What is the pressure in mmHg?

kobusy [5.1K]

Answer:

The pressure in mmHg is 1253 (option C)

Explanation:

Two quantities are directly proportional if when multiplying or dividing one of them by a number, the other is multiplied or divided by that number. In other words, the magnitudes are directly proportional when one magnitude increases and so does the other in the same proportion; or when one magnitude decreases and so does the other in the same proportion.

The rule of three or is a way of solving proportionality problems between three known values and an unknown value, which can be applied to directly proportional quantities as follows:

a ⇒ b

c ⇒ x

So $x=\frac{c*b}{a}$

where a, b and c are data and x is the unknown value to be calculated.

In this case, knowing that 1 Torr = 1 mmHg, the rule of three can be applied as follows: if 1 torr is equal to 1 mmHg, 1253 torr is equal to how many mmHg?

$pressure=\frac{1253 torr*1 mmHg}{1 torr}$

pressure= 1253 mmHg

<u><em>The pressure in mmHg is 1253 (option C)</em></u>

6 0

3 years ago