Consider the titration of a 73.9 mL sample of 0.13 M HC2H3O2 with 6.978 M NaOH. Ka(HC2H3O2) = 1.8x10-5 Determine the initial pH before any NaOH is added. Express your answer using two decimal places.Consider the titration of a 46.6 mL sample of 0.078 M HC2H3O2 with 1.135 M NaOH. Ka(HC2H3O2) = 1.8x10-5 Determine the volume of added base required to reach the equivalence point. Answer in units of milliliters.
Consider the titration of a 17.2 mL sample of 0.128 M HC2H3O2 with 0.155 M NaOH. Ka(HC2H3O2) = 1.8x10-5 Determine the pH at 0.46 mL of added base.
Answers
Answer:
1. pH = 2,82
2. 3,20mL of 1,135M NaOH
3. pH = 3,25
Explanation:
The buffer of acetic acid (HC₂H₃O₂) is:
HC₂H₃O₂ ⇄ H⁺ + C₂H₃O₂⁻
The reaction of HC₂H₃O₂ with NaOH produce:
HC₂H₃O₂ + NaOH → C₂H₃O₂⁻ + Na⁺ + H₂O
And ka is defined as:
ka = [H⁺] [C₂H₃O₂⁻] / [HC₂H₃O₂] = 1,8x10⁻⁵ (1)
1. When in the solution you have just 0,13M HC₂H₃O₂ the concentrations in equilibrium will be:
[H⁺] = x
[C₂H₃O₂⁻] = x
[HC₂H₃O₂] = 0,13 - x
Replacing in (1)
[x] [x] / [0,13-x] = 1,8x10⁻⁵
x² = 2,34x10⁻⁶ - 1,8x10⁻⁵x
x² - 2,34x10⁻⁶ + 1,8x10⁻⁵x = 0
Solving for x:
x = - 0,0015 (Wrong answer, there is no negative concentrations)
x = 0,0015
As [H⁺] = x = 0,0015 and pH is -log [H⁺], pH of the solution is 2,82
2. The equivalence point is reached when moles of HC₂H₃O₂ are equal to moles of NaOH. Moles of HC₂H₃O₂ are:
0,0466L × (0,078mol / L) = 3,63x10⁻³ moles of HC₂H₃O₂
In a 1,135M NaOH, these moles are reached with the addition of:
3,63x10⁻³ moles × (L / 1,135mol) = 3,20x10⁻³L = 3,20mL of 1,135M NaOH
3. The initial moles of HC₂H₃O₂ are:
0,0172L × (0,128mol / L) = 2,20x10⁻³ moles of HC₂H₃O₂
As the addition of NaOH spent HC₂H₃O₂ producing C₂H₃O₂⁻. Moles of C₂H₃O₂⁻ are equal to moles of NaOH and moles of HC₂H₃O₂ are initial moles - moles of NaOH. That means:
0,46x10⁻³L NaOH × (0,155mol / L) = 7,13x10⁻⁵ moles of NaOH ≡ moles of C₂H₃O₂⁻
Final moles of HC₂H₃O₂ are:
2,20x10⁻³ - 7,13x10⁻⁵ = 2,2187x10⁻³ moles of HC₂H₃O₂
Using Henderson-Hasselbalch formula:
pH = pka + log₁₀ [C₂H₃O₂⁻] / [HC₂H₃O₂]
Where pka is -log ka = 4,74. Replacing:
pH = 4,74 + log₁₀ [7,13x10⁻⁵] / [2,2187x10⁻³ ]
pH = 3,25
I hope it helps!
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B- 1.204 x 1024 g/mol
C- 6.02 x 1023 g/mol
D- 31.9988 g/mol
Answers
Answer:
D- 31.9988 g/mol
Explanation:
The molar mass of a substance is the mass in grams of one mole of the substance. For a compound, the molar mass is the gram - formula mass or gram - molecular weight. It is determined by the addition of its component atomic masses;
To find molar mass of O₂;
Atomic mass of O = 15.9994g/mol
Molar mass of O₂ = 2(15.9994) = 31.9988g/mol
Answers
Answer:
0.113 M
Explanation:
Since B and D are on opposite sides of the reaction, the concentration of D increases when the concentration of B decreases. The amount by which D increases is determined by the coefficients of B and D in the balanced chemical equation:
[D]=(0.045 M)=0.113 M.
Answers
Answer:
325mg of Aspririn
Explanation:
First you should note the information that the problem gives you:
- The bottle of Aspirin has 5gr (grains)
- 1gr(grain) = 65mg (miligrams)
Also, the problem is asking about how many aspirin are in 5 gr (grains), so you should use a conversion factor, as follows:
-First you should put the quantity you need to convert:
-Then you write the denominator of the conversion factor that must have the same units that you want to convert, in this case gr:
-Then you write the numerator with the units that you want to obtain and the numerical equivalence between the units, in this case:
-Finally you multiply numerators and divide by denominators:
Answers
Explanation:
pH is use calculate the acidic strength of a substance ,
The value of pH is calculated as , negative log of the concentration of Hydrogen ions .
Therefore ,
pH = - log [ H ⁺]
rearranging the above equation , to find the hydrogen ion concentration . log [ H ⁺] = pH
log [ H ⁺] = - pH
[ H ⁺] = antilog ( - pH )
Hence , from the question , the hydrogen ions can be calculated by using the above equation ,
( 1 )
pH = 6.95
Since ,
[ H ⁺] = antilog ( - pH )
[ H ⁺] = antilog ( - 6.95 )
[ H ⁺] = 1.12 * 10 ⁻⁷
( 2 )
pH = 7.25
Since ,
[ H ⁺] = antilog ( - pH )
[ H ⁺] = antilog ( - 7.25 )
[ H ⁺] = 5.62 * 10 ⁻⁸
( 3 )
pH = 8.1
Since ,
[ H ⁺] = antilog ( - pH )
[ H ⁺] = antilog ( - 8.1 )
[ H ⁺] = 7.94 * 10 ⁻⁹
b.unsaturated.
c.saturated.
d.supersaturated.
Answers
Answer:
d. supersaturated.
Explanation:
A solution naturally contains a solute and a solvent. The solute is the solid substance that dissolves in the solvent, which is usually a liquid substance. A solution has a maximum amount of solute that can dissolve in its constituent solvent.
However, when the amount of dissolved solute in a solution at a given temperature is greater than the amount that can permanently remain in the solution at that temperature, the solution is said to be SUPERSATURATED. This means that the solution contains more than the maximum amount of solute.
a hurricane
a volcanic eruption
a landslide
an earthquake
Answers
Answer: I believe the answer is an earthquake.
Explanation: Sorry If I am wrong!
Answer:
earthquake
Explanation:
I took the k12 test