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2 years ago

29. Some physical changes involve chemical reactions. TRUE FALSE

Chemistry

1 answer:

Verizon [17]2 years ago

5 0

True. Some physical changes involve chemical reactions. Ice melting is an example of a chemical change in matter

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Your task is to create a buffered solution. You are provided with 0.10 M solutions of formic acid and sodium formate. Formic aci

Anton [14]

Answer:

15.2mL of the 0.10M sodium formate solution and 4.8mL of the 0.10M formic acid solution.

Explanation:

To find the pH of a buffer based on the concentration of the acid and conjugate base we must use Henderson-Hasselbalch equation:

pH = pKa + log [A⁻] / [HA]

<em>Where [A⁻] could be taken as moles of the sodium formate and [HA] moles of the formic acid</em>

<em />

4.25 = 3.75 + log [A⁻] / [HA]

0.5 = log [A⁻] / [HA]

3.162 = [A⁻] / [HA] <em>(1)</em>

As both solutions are 0.10M and you want to create 20mL of the buffer, the moles are:

0.10M * 20x10⁻³L =

2x10⁻³moles = [A⁻] + [HA] <em>(2)</em>

Replacing (2) in (1):

3.162 = 2x10⁻³moles - [HA] / [HA]

3.162 [HA] = 2x10⁻³moles - [HA]

4.162[HA] = 2x10⁻³moles

[HA] = 4.805x10⁻⁴ moles

[A⁻] = 2x10⁻³moles - 4.805x10⁻⁴ moles = 1.5195x10⁻³moles

That means, to create the buffer you must add:

[A⁻] = 1.5195x10⁻³moles * (1L / 0.10mol) = 0.0152L =

<h3>15.2mL of the 0.10M sodium formate solution</h3>

[HA] = 4.805x10⁻⁴ moles * (1L / 0.10mol) = 0.0048L =

<h3>4.8mL of the 0.10M formic acid solution</h3>

4 0

3 years ago

An object is seen to either speed up, slow down, or change direction. these behaviors are caused by what ?

denpristay [2]

I believe the correct answer from the choices listed above is option D. An object is seen to either speed up, slow down, or change direction due to <span>unbalanced forces. When a system is subjected to unbalanced forces, the object would tend to move or change in motion. Hope this answers the question.</span>

7 0

3 years ago

Read 2 more answers

FIRST TO ANSWER CORRECTLY GETS BRAINELSIT! pls asap :)

zmey [24]

The protons! Is it the answer

4 0

3 years ago

Read 2 more answers

CH3COOH mc015-1.jpg CH3COO– (aq) + H+(aq) What will happen to the chemical equilibrium of the solution if CH3COONa is added?

andrey2020 [161]

The equilibrium will shift to the left or the backward reaction since addition of <span>CH3COONa will add more CH3COO- ions to the solution. The formation of reactants are promoted.</span>

7 0

3 years ago

When a 2.00 g sample of KCl is dissolved in water in a calorimeter that has a total heat capacity of 1.28 kJ ⋅ K − 1 , the tempe

Alchen [17]

Answer : The molar heat of solution of KCl is, 17.19 kJ/mol

Explanation :

First we have to calculate the heat of solution.

$q=c\times (\Delta T)$