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
VMariaS [17]
3 years ago
6

Glycolic acid, which is a monoprotic acid and a constituent in sugar cane, has a pKa of 3.9. A 25.0 mL solution of glycolic acid

is titrated to the equivalence point with 35.8 mL of 0.020 M sodium hydroxide solution. What is the pH of the resulting solution at the equivalence point?
Chemistry
1 answer:
Phoenix [80]3 years ago
7 0

Answer:

pH = 8.0

Explanation:

First, we have to calculate the moles of NaOH.

35.8 \times 10^{-3}L.\frac{0.020mol}{L} =7.2\times 10^{-4}mol

Let's consider the balanced equation.

C₂H₄O₃ + NaOH ⇒ C₂H₃O₃Na + H₂O

The molar ratio C₂H₄O₃: NaOH: C₂H₃O₃Na is 1: 1: 1. So, when 7.2 × 10⁻⁴ moles of NaOH react completely with 7.2 × 10⁻⁴ moles of C₂H₄O₃ they form 7.2 × 10⁻⁴ moles of C₂H₃O₃Na.

The concentration of C₂H₃O₃Na is:

\frac{7.2\times 10^{-4}mol}{60.8 \times 10^{-3}L} =0.012M

C₂H₃O₃Na dissociates according to the following equation:

C₂H₃O₃Na(aq) ⇒ C₂H₃O₃⁻(aq) + Na⁺(aq)

C₂H₃O₃⁻ comes from a weak acid so it undergoes basic hydrolisis.

C₂H₃O₃⁻ + H₂O ⇄ C₂H₄O₃ + OH⁻

If we know that pKa for C₂H₄O₃ is 3.9, we can calculate pKb for C₂H₃O₃⁻ using the following expression:

pKa + pKb = 14

pKb = 14 -3.9 = 10.1

10.1 = -log Kb

Kb = 7.9 × 10⁻¹¹

We can calculate [OH⁻] using the following expression:

[OH⁻] = √(Kb.Cb)               <em>where Cb is the initial concentration of the base</em>

[OH⁻] = √(7.9 × 10⁻¹¹ × 0.012M) = 9.7 × 10⁻⁷ M

Now, we can calculate pOH and pH.

pOH = -log [OH⁻] = -log (9.7 × 10⁻⁷) = 6.0

pH + pOH = 14

pH = 14 - pOH = 14 - 6.0 = 8.0

You might be interested in
Five Biomedical Importance of Nucleotides
Brut [27]

Explanation:

BIOMEDICAL IMPORTANCE

In addition to serving as precursors of nucleic acids, purine and pyrimidine nucleotides participate in metabolic functions as diverse as energy metabolism, protein synthesis, regulation of enzyme activity, and signal transduction.

4 0
2 years ago
Explain how stagnant sulfureted water may greatly accelerate metallic corrosion. (See the Email Link in Moodle) | (7 marks)
slavikrds [6]

Answer:

sulfur promotes oxide-reduction reactions.

Explanation:

In stagnant water, some solutes tend to precipitate. When Sulfur precipitate and touch a metal, Sulfur is being reduced and the metal is oxidated. This depends of potential redox of each element.  

6 0
3 years ago
Name two solid liquid and gaseous element at the normal temperature and normal press<br>ure​
liubo4ka [24]

Answer:

Solid: calcium and potassium

Liquid: mercury and bromine

Gaseous: oxygen and fluorine

Explanation:

Matter exists in three different states namely: solid, gaseous and liquid. Elements that are found in nature are classified as matter. Since, these elements are grouped as matter, they can either be found as either solids, liquids or gases at normal temperature and pressure.

At normal temperature (20°C or 293K) and pressure (1 atm), the following elements are found to exists in the respective state of matter:

Solid: Calcium (Ca) and potassium (K)

Liquid: Mercury (Hg) and bromine (Br)

Gaseous: Oxygen (O) and fluorine (F)

7 0
3 years ago
Difference between melting point and melting range
Rudik [331]
The temperature at which a given solid will melt is called melting point.

The melting range is the span of temperature from the point at which the crystals first begin to liquefy to the point at which the entire sample is liquid.
5 0
3 years ago
Ethyl butyrate, ch3ch2ch2co2ch2ch3, is an artificial fruit flavor commonly used in the food industry for such flavors as orange
kakasveta [241]

Answer:

             14.15 g of Ethyl Butyrate

Solution:

The Balance Chemical Equation is as follow;

           Butanoic Acid  +  Ethanol    →    Ethyl Butyrate  +  Water

Molar Mass of Butanoic Acid  =  88.11 g.mol⁻¹

Molar Mass of Ethanol  =  46.07 g.mol⁻¹

Molar Mass of Ethyl Butyrate  =  116.16 g.mol⁻¹

Molar Mass of Water  =  18.01 g.mol⁻¹

Step 1: Calculating Theoretical Yield:

According to Equation,

           88.11 g (1 mol) Butanoic Acid forms  =  116.16 g (1 mol) Ethyl Butyrate

So,

                 13.58 g Butanoic Acid will form  =  X g of Ethyl Butyrate

Solving for X,

                     X  =  (13.58 g × 116.16 g) ÷ 88.11 g

                     X  =  17.90 g

                     Theoretical Yield  =  17.90 g

Step 2: Calculating Actual Yield:

As,

                     %age Yield  =  Actual Yield ÷ Theoretical Yield × 100

Solving for Actual Yield,

                      Actual Yield  =  %age Yield × Theoretical Yield ÷ 100

Putting Values,

                      Actual Yield  =  79.1 × 17.90 ÷ 100

                      Actual Yield =  14.15 g of Ethyl Butyrate

6 0
3 years ago
Other questions:
  • Conditions for an experimental chemistry reaction require a temperature of 300 K. The temperature in the lab is 55°F. Which of t
    5·2 answers
  • Will magnesium and fluorine atoms most likely form an ionic bond or a covalent bond?
    12·2 answers
  • What substance is used in a nuclear reactor to absorb heat released from the reactor?
    7·2 answers
  • I need help on #2 a and b. please explain steps and answer
    7·1 answer
  • Two types of heterogeneous mixtures are suspensions and colloids.<br>true or false<br><br>​
    15·1 answer
  • Volume (at STP) of 5.2x10^26 molecules of CH4?
    10·1 answer
  • 7.5 moles of nitrogen gas (N2) is formed in the following reaction. How many grams
    12·1 answer
  • Calcium chloride solution reacts with sodium carbonate solution
    8·1 answer
  • In witch step did a chemical change most likely occur
    14·1 answer
  • What is the weighted average of a nail in the sample data given?
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!