1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
iren [92.7K]
3 years ago
14

What mass of sodium benzoate should be added to 150.0 ml of a 0.15 m benzoic acid solution in order to obtain a buffer with a ph

of 4.25? (assume no volume change.)?
Chemistry
1 answer:
Monica [59]3 years ago
3 0
When we know the Pka value = 4.19 

so, we are going to use H-H equation:

PH = Pka + ㏒[benzoate/benzoic acid]

when we have PH = 4.25 

and Pka = 4.19 

so by substitution:

4.25 = 4.19 + ㏒[benzaoate/ benzoic acid]

∴ [benzaoate/benzoic acid] = 1.148 M

when the [benzoic acid ] = 0.15 m 

∴ [benzaoate] = 1.148M * 0.15m 

                        = 0.1722 M

∴ moles of sodium benzoate = molarity * volume L

                                                 = 0.1722 M * 0.15 L 

                                                 = 0.02583 moles

∴ the mass = moles * molar mass

                   = 0.02583 moles* 144 g/mol

                   = 3.72 g


You might be interested in
Please help!!<br> I don’t understand
laiz [17]
<h3>Answer:</h3>

150 g Si

<h3>General Formulas and Concepts:</h3>

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

  1. Brackets
  2. Parenthesis
  3. Exponents
  4. Multiplication
  5. Division
  6. Addition
  7. Subtraction
  • Left to Right<u> </u>

<u>Chemistry</u>

<u>Atomic Structure</u>

  • Reading a Periodic Table
  • Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

<u>Stoichiometry</u>

  • Use Dimensional Analysis
<h3>Explanation:</h3>

<u>Step 1: Define</u>

[Given] 3.2 × 10²⁴ atoms Si

[Solve] grams Si

<u>Step 2: Identify Conversions</u>

Avogadro's Number

[PT] Molar Mass of Si - 28.09 g/mol

<u>Step 3: Convert</u>

  1. [DA] Set up:                                                                                                       \displaystyle 3.2 \cdot 10^{24} \ atoms \ Si(\frac{1 \ mol \ Si}{6.022 \cdot 10^{23} \ atoms \ Si})(\frac{28.09 \ g \ Si}{1 \ mol \ Si})
  2. [DA] Multiply/Divide [Cancel out units]:                                                            \displaystyle 149.266 \ g \ Si

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. Instructed to round to 2 sig figs.</em>

149.266 g Si ≈ 150 g Si

4 0
3 years ago
PLEASE ANSWER
vodka [1.7K]

Answer:

  • <u><em>B. Negative association</em></u>

<u><em></em></u>

Explanation:

<em>Negative association</em> is when the independent and dependent variables move in opposite directions: if the dependent variable increases, the independent variable decreases, and if the dependent variable decreases, the independent variable increases.

As you see in the diagram, as you move to the right on the horizontal axis, meaning that the independent variable is increasing, the points lie lower, meaning that the independent variable decreases.

Therefore, if you draw a line of best fit, it will have a negative slope. A negative slope indicates <em>negative association.</em>

The graph certainly shows association as there is a clear trend; else the points would be randomly dispersded.

7 0
3 years ago
Alpine Marmots are a type of rodent that have the ability to decrease their body activity to conserve food. These marmots most l
tia_tia [17]

Hello!

The answer is C. Hibernate during the cold winter months.

Why?

Alpine marmots are known for having a long hibernation duration which starts in October (winther) and ends in April (summer) (about 7 months). During this long period, they are able to reduce their bear beats from 200 per minute to just 30 or 38 beats, and their breaths from 60 breaths/minute to 1-3 breaths/minute, guaranteeing an extreme energy saving process.

Have a nice day!

5 0
3 years ago
1.What is another term for the 24 hour clock?
s344n2d4d5 [400]

Answer:

military time

Explanation:

military time

5 0
3 years ago
The reaction of hydrogen and iodine to produce hydrogen iodide has a Kc of 54.3 at 703 K. Given the initial concentrations of H2
pentagon [3]

Answer:

[HI] = 0.7126 M

Explanation:

Step 1: Data given

Kc = 54.3

Temperature = 703 K

Initial concentration of H2 and I2 = 0.453 M

Step 2: the balanced equation

H2 + I2 ⇆ 2HI

Step 3: The initial concentration

[H2] = 0.453 M

[I2] = 0.453 M

[HI] = 0 M

Step 4: The concentration at equilibrium

[H2] = 0.453 - X

[I2] = 0.453 - X

[HI] = 2X

Step 5: Calculate Kc

Kc = [Hi]² / [H2][I2]

54.3 = 4x² / (0.453 - X(0.453-X)

X = 0.3563

[H2] = 0.453 - 0.3563 = 0.0967 M

[I2] = 0.453 - 0.3563 = 0.0967 M

[HI] = 2X = 2*0.3563 = 0.7126 M

3 0
3 years ago
Other questions:
  • Which diatomic molecule is formed when the two atoms share six electrons
    5·2 answers
  • What is true that if at the same temperature 2 objects have equal masses, but different densities
    9·1 answer
  • After reading “The Crisis, No. 1,” what do you think Paine means by the line, "These are the times that try men’s souls"? Cite e
    8·2 answers
  • Soil is a renewable resource if properly maintained. Which of the following helps to maintain healthy soil?
    10·2 answers
  • Water, h2o, is a molecule made of oxygen and hydrogen. the bonds that hold water molecules together are due to shared electrons,
    5·2 answers
  • How many mL. of 0.200 M Pb(NOs)2 solution are needed to obtain 0.875 grams of Pb(NO:)2?
    11·1 answer
  • Balance the equation <br><br> __Ni(CIO)3 → _NiCl2+ _02
    9·1 answer
  • What particles make up an atom?
    15·1 answer
  • Which of the following is a balanced equation?<br><br>Select one:<br>a. A<br>b. B<br>c. C<br>d. D​
    7·2 answers
  • If an object goes through a chemical reaction but does not change in mass that object has
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!