3.65
Further explanationGiven:
100 ml of a buffer solution containing 0.600 molar formic acid and 0.300 m sodium formate.The Ka for formic acid is 1.8 x 10⁻⁴.Question:
What would be the final ph if 0.0100 moles of solid NaOH were added to this buffer?
The Process:
Step-1
Let us prepare all the moles of substances.
[tex]\boxed{ \ n = MV \ }[/tex]
Moles of HCOOH =
[tex]\boxed{ \ 0.600 \ \frac{mol}{L} \times 100 \ ml = 60 \ mmol \ }[/tex]
Moles of HCOONa =
[tex]\boxed{ \ 0.300 \ \frac{mol}{L} \times 100 \ ml = 30 \ mmol \ }[/tex]
Moles of NaOH =
[tex]\boxed{ \ 0.0100 \ moles = 10 \ mmol \ }[/tex]
Step-2
Let use the ICE table (in mmol).
[tex]\boxed{ \ HCOOH_{(aq)} + NaOH_{(s)} \rightarrow HCOONa_{(aq)} + H_2O_{(l)} \ }[/tex]
Initial: 60 10 30 -
Change: -10 -10 +10 +10
Equlibrium: 50 - 40 10
NaOH as a strong base acts as a limiting reagent.
The remaining HCOOH as a weak acid and HCOONa salt forms an acidic buffer system.
The HCOONa salt has valence = 1 according to the number of HCOO⁻ ions as a weak part, i.e., [tex]\boxed{ \ HCOONa \rightleftharpoons HCOO^- + Na^+ \ }[/tex]
HCOOH and HCOO⁻ are conjugate acid-base pairs.
Step-3
To calculate the specific pH of a given buffer, we need using The Henderson-Hasselbalch equation for acidic buffers:
[tex]\boxed{ \ pH = pK_a + log\frac{[A^-]}{[HA]} \ }[/tex]
where,
Ka represents the dissociation constant for the weak acid;[A-] represent the concentration of the conjugate base (i.e. salt); [HA] is the concentration of the weak acid.[tex]\boxed{ \ pH = pK_a + log\frac{[HCOO^-]}{[HCOOH]} \ }[/tex]
[tex]\boxed{ \ pH = -log(1.8 \times 10^{-4}) + log \Big(\frac{40}{50}\Big) \ }[/tex]
[tex]\boxed{ \ pH = 4 - log \ 1.8 - 0.0969 \ }[/tex]
[tex]\boxed{ \ pH = 4 - 0.2553 - 0.0969 \ }[/tex]
[tex]\boxed{ \ pH = 3.65 \ }[/tex]
Thus, the pH of this buffer equal to 3.65.
_ _ _ _ _ _ _ _ _ _
What if we calculate the buffer pH value before the addition of NaOH?
Moles of HCOOH = 60 mmol
Moles of HCOONa = 30 mmol
[tex]\boxed{ \ pH = pK_a + log\frac{[HCOO^-]}{[HCOOH]} \ }[/tex]
[tex]\boxed{ \ pH = -log(1.8 \times 10^{-4}) + log \Big(\frac{30}{60}\Big) \ }[/tex]
[tex]\boxed{ \ pH = 4 - log \ 1.8 - 0.301 \ }[/tex]
[tex]\boxed{ \ pH = 4 - 0.2553 - 0.301 \ }[/tex]
[tex]\boxed{ \ pH = 3.44 \ }[/tex]
Thus, the initial pH of this buffer is 3.44. This proves the nature of the buffer that keeps the pH value relatively unchanged with the addition of a strong electrolyte.
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Answer: it must be 6.01 kJ.
Explanation:
Latent heat of freezing is the amount of heat released to convert 1 mole of liquid to 1 mole of solid at atmospheric pressure.
[tex]H_2O(l)\rightarrow H_2O(s)[/tex]
Given: latent heat of freezing is 6.01 kJ.
Latent heat of fusion is the amount of heat required to convert 1 mole of solid to 1 mole of liquid at atmospheric pressure. If latent heat of freezing is 6.01 kJ, latent heat of fusion will be same but the heat will be absorbed.
[tex]H_2O(s)\rightarrow H_2O(l)[/tex]
#1: Nitrogen (N) is made up of 99.632% 14N and 0.368% 15N. The atomic mass of 14N is 14.003 amu. The atomic mass of 15N is 15.000 amu. What is the average atomic mass of nitrogen?
A. 14.0 amu
B. 14.006 amu
C. 15.00 amu
D. 15.50 amu
**my answer: B.
but idk 100% :/,
A liquid that evaporates at a slow rate exhibits __________.
strong intermolecular forces
weak intermolecular forces
no intermolecular forces
a low volatility
Answer:
The correct answer is "strong intermolecular forces".
Explanation:
During the evaporation phase, external energy is applied to a substance that results in the separation of their molecules. The evaporation rate is closely related to the intermolecular forces within the substance. A liquid that evaporates at a slow rate exhibits strong intermolecular forces. This happens because the energy applied to the liquid would need more time to separate the molecules of a substance that are strongly attached.
If carbon monoxide reaches a temperature of over 1,100 degrees Fahrenheit, it will ignite in a combustion reaction with oxygen. What would the product(s) of the reaction be?
Answer:
2CO2 or A
Explanation: i just got its right!
I really don't get this question, could someone help
In a 1.0× 10–2 M solution of NH4ClO4(aq), identify the relative molar amounts of these species.
In a 1.0× 10–2 M solution of NH4ClO4(aq), the relative molar amounts of NH4+, ClO4-, and NH4ClO4 are 1:1:1.
Explanation:In a 1.0× 10–2 M solution of NH4ClO4(aq), the relative molar amounts of the species can be determined by looking at the balanced chemical equation for NH4ClO4 dissolving in water.
The balanced equation is NH4ClO4(aq) → NH4+(aq) + ClO4-(aq).
From the equation, we can see that for every 1 mole of NH4ClO4, 1 mole of NH4+ and 1 mole of ClO4- are produced.
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Which three temperature readings all mean the same thing? Question options: 273 Kelvin, 0 degrees Celsius, 32 degrees Fahrenheit 373 Kelvin, 100 degrees Celsius, 273 degrees Fahrenheit 100 Kelvin, 0 degrees Celsius, 32 degrees Fahrenheit 273 Kelvin, 100 degrees Celsius, 212 degrees Fahrenheit
273 Kelvin, 0 degrees Celsius, 32 degrees Fahrenheit
Explanation;Kelvin, degrees Celsius and degrees Fahrenheit, all are units that may be used to measure temperature.
Each unit may be converted to another using the following formulas.
°C = (°F - 32) × 5 / 9 °F = (°C ×1.8) + 32 K = °C + 273.0°C = K - 273.0Which means 0 °C is equivalent to 273 Kelvin, (K = °C + 273.0) and also equivalent to 32 degrees Fahrenheit (°F = (°C ×1.8) + 32 ).
AgO --> Ag2O; balance this equation/charges,
If you set up an experiment with two different independent variables, then the results would be_____.
A. inconclusive; you would not know which of the two variables caused the change
B. definitive; the results would be more accurate if you change two variables at a time
C. conclusive; showing a strong correlation between dependent and independent variables
D. somewhat conclusive; you know the change resulted from one of the variables
Answer:
d
Explanation:
A liquid with a high surface tension exhibits __________.
strong cohesive forces
weak cohesive forces
strong adhesive forces
weak adhesive forces
Answer: strong cohesive forces
Explanation:
Surface tension is the net downward force acting on the surface of liquids due to the cohesive nature of liquids.
The force of attraction between similar molecules are called as cohesive forces and forces among different molecules are called as adhesive forces.
For example: Water molecules are bonded by strong hydrogen bonding between the hydrogen atom and the electronegative oxygen atom. Thus water molecules present on the surface are strongly attracted by the molecules present below the surface and thus act as a stretched membrane.
The surface acquires a minimum surface are and thus acquire a spherical shape.
Thus the liquids with a high surface tension exhibits strong cohesive forces.
The diprotic acid h2co3 can produce two buffers depending on the ph of the solution. identify the conjugate acid/base pair from carbonic acid that would form the most basic buffer.
Consider two solutions, solution a and solution
b. [h+] in solution a is 370 times greater than that in solution
b. part a what is the difference in the ph values of the two solutions?
Final answer:
The difference in the pH values of two solutions, where one solution has an H+ concentration 370 times greater than the other, is approximately 2.568 pH units, calculated using a logarithmic scale.
Explanation:
The question asks to calculate the difference in the pH values of two solutions where the concentration of hydrogen ions [H+] in solution A is 370 times greater than that in solution B. The pH scale is logarithmic, which means a tenfold increase in hydrogen ion concentration results in a decrease of 1 unit in pH. Therefore, for each 10-fold difference in concentration, there is a 1 unit difference in pH.
Since the concentration in solution A is 370 times greater, we first need to find how many times 10 fits into 370 to determine the pH difference. We can do this by taking the logarithm (base 10) of 370:
pH difference = log(370) = 2.568
Therefore, the difference in pH between solution A and solution B is approximately 2.568 pH units.
compare and contrast neap tides and spring tides discuss when they occur as well as the alignment of the earth moon sun system
Answer:
The spring tides occur seven days after the spring tide and the spring tides occur twice in the lunar year.
Explanation:
A spring tide is a tide in which there is a greatest difference between a high and low tide is the greatest. A spring tide occurs when the earth, the moon, and the sun are in the straight line. A neap tide, on the other hand, occurs when the sun, moon, and earth make a three triangle kind of a triangle. It occurs when there is a least between the highest and lowest tide.
Neap tides occur twice a month when the sun and moon are at right angles to the earth. Spring tide, on the other hand, occur at new moon or full moon
What steps are important in the process of creating a scientific theory? (1 point)
hypothesizing, observing, and testing
creating a prototype and trouble-shooting
analyzing, offering an opinion, and evaluating
trouble-shooting, hypothesizing, and evaluating
The important steps in the process of creating a theory are the following: hypothesizing, observing, and testing. You first conduct observation to identify problem or situation that will lead to your theory. Next step is to formulate an intelligent guess called as the hypothesis. This hypothesis will be tested if it fit to be a theory.
Help me please 11 and 12
What is solubility? solubility is the minimum amount of a solvent that can be used to make a solution. solubility is the pressure necessary to create a solution. solubility is the temperature that can be used to mix a solution. solubility is the ability of one substance to dissolve in another?
Answer:
Option 4.
Explanation:
Solubility may be defined as the ability of a solute to dissolve in a solvent. The maximum ability of solute to dissolve in a solvent can be measured by its solubility.
For example: alcohol ( solute) can dissolve in a solvent( water). Alcohol has high solubility for water and can easily dissolve in water.
Hence, the correct answer is option 4.
When a substance has high solubility, it readily dissolves in a solvent, resulting in a concentrated solution. The correct statement is Solubility is the ability of one substance to dissolve in another.
Solubility refers to the maximum amount of a solute that can dissolve in a given amount of solvent at a specific temperature and pressure. It is a measure of how well a substance can dissolve in another substance to form a homogeneous mixture called a solution.
Solubility is typically expressed in terms of the amount of solute that can dissolve in a given amount of solvent, often measured in grams per liter (g/L) or moles per liter (mol/L). It is influenced by factors such as temperature, pressure, the nature of the solute and solvent, and the presence of other substances.
Therefore, the correct statement is: Solubility is the ability of one substance to dissolve in another.
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which functional group is found in an ester?
The functional group found in an ester is a carbonyl group with an attached second oxygen atom that is bonded to a carbonyl carbon substituent by a single bond, usually a pair of alkyl or aromatic groups. In addition, it can be shown in text as RCOOR or occasionally as ROCOR, which made them responsible in the distinctive and attractive odors and flavors of many flowers, perfumes, and ripe fruits.
Two balloons, one with a charge of 4.0 × 10-6 coulombs and the other with a charge of 8.2 × 10-6 coulombs, are kept 2.0 meters apart. What is the electric force between the two balloons? (k = 9.0 × 109newton·meter2/coulombs2) Show quoted text
Answer is C for plato users
7.3 × 10-2
A mothball, composed of naphthalene (c10h8), has a mass of 1.64 g . part a how many naphthalene molecules does it contain?
A 50.0 mL sample of 1.54×10−2 M NaSO4 is added to 50.0 mL of 1.28×10−2 Ca(NO3)2. What percentage of the Ca2+ remains unprecipitated?,
How many moles of CO2 are in 1.0L at 25 degrees C and 95 kPa?
Which two properties are explained by the pool-of-shared-electrons model for metals?
Answer:
Conductivity
Ductility
malleability
Explanation:
There are many properties of metals which can be explained by pool-of-shared electrons or electron sea model.
a) As electrons are considered to be free like in a sea so they are able to conduct electricity easily. Thus metals are conducting in nature.
b) The bonds are random in between metal atoms and can be broken easily and can be formed easily hence as per model the metal are highly ductile and malleable in nature.
Rounded to the nearest whole number, how many neutrons, on average, are in an atom of osmium? 76 114 190 266
Answer: The number of neutrons in osmium is 114.
Explanation:
Atomic number is defined as the number of protons that are present in an atom. It is represented as 'Z'
Atomic number = Number of protons
Mass number is defined as the sum of number of protons and number of neutrons that are present in an atom. It is represented as 'A'
Mass number = Number of neutrons + Number of protons
We know that:
Atomic number of osmium = 76
Mass number of osmium = 190
Number of neutrons = 190 - 76 = 114
Hence, the number of neutrons in osmium is 114.
What is the main difference between an isotope and an ion?
a. an ion has extra protons.
b. an isotope has extra neutrons.
c. isotopes are radioactive while ions are not.
d. an ion always has a positive or a negative charge?
When a wave encounters a large gapless barrier which of the following describes what will happen
What are five characteristics of a group on the periodic table?
how many liters of nitrogen gas are needed to react with 90.0 g of potassium at STP in order to produce potassium nitride according to the following reactions?
Answer:8.59L
Explanation:
The other answer has all the right steps but the atomic mass of potassium is actually 39.098 not 19.
Final answer:
Approximately 8.58 liters of nitrogen gas are needed to react with 90.0 g of potassium to produce potassium nitride at STP, after calculating moles of potassium and its stoichiometric conversion to moles and then volume of nitrogen gas.
Explanation:
To determine how many liters of nitrogen gas are needed to react with 90.0 g of potassium to produce potassium nitride, we first need to understand the correct chemical reaction for forming potassium nitride from potassium and nitrogen gas. The reaction is as follows:
6 K(s) + N₂(g) → 2 K₃N(s)
Firstly, calculate the moles of potassium. The molar mass of potassium (K) is approximately 39.10 g/mol. Therefore, the moles of potassium in 90.0 g are calculated as:
90.0 g K × (1 mol K / 39.10 g K) = 2.30 mol K
From the balanced equation, it is clear that 6 moles of potassium react with 1 mole of nitrogen gas. Hence, the moles of nitrogen gas needed can be calculated as:
2.30 mol K × (1 mol N₂ / 6 mol K) = 0.383 mol N₂
At Standard Temperature and Pressure (STP), 1 mole of any gas occupies 22.4 liters. Therefore, the volume of nitrogen gas required at STP can be found as:
0.383 mol N₂ × 22.4 L/mol = 8.58 L N₂
Therefore, approximately 8.58 liters of nitrogen gas are needed to react with 90.0 g of potassium to produce potassium nitride at STP.
Fill in the blank: You can find the number of __________ in any atom by subtracting the atomic number from the mass number.
A.
electrons
B.
neutrons
C.
protons
The atomic number of an atom is the number of its electrons which is equal to the number of its protons. Mass number is the sum of number of protons and neutrons. Hence, substracting atomic number from mass number give us the number of neutrons.
What is mass number ?An atom is made of subatomic particles, electrons, protons and neutrons. The protons and neutrons are located inside the nucleus and the electrons revolving around the nucleus through fixed energy levels.
In a neutral atom, the number of electrons is equal to the number of protons. This number is called the atomic number of the atom. The sum of number of neutrons and number of protons is called mass number of the atoms.
Substracting atomic number from mass number is the subtraction of number of protons from the mass number. Hence, it gives the number of neutrons. Thus, option B is correct.
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This is is the common name for the aqueous cation h3o+, formed when a water molecule combines with the proton from a hydrogen atom.
When ions form they have the electron configuration of: A) Alkali Metals
B) Alkaline Earth Metal C) Halogens D) Noble Gas
Alkali metals have a general outermost electronic configuration of [tex] ns^{1} [/tex]
Alkali earth metals have a general outermost electronic configuration of [tex] ns^{2} [/tex]
The +1 ion of the alkali metals has a stable octet configuration of the nearest noble gas as the outermost ns electron is lost.
The +2 ion of the alkaline earth metals has a stable configuration of the nearest noble gas as the two electrons in the outermost ns shell are lost.
How many moles of fe(oh)2 [ksp = 1.8 ´ 10-15] will dissolve in 1.0 liter of water buffered at ph = 10.37?
Answer : The moles of [tex]Fe(OH)_2[/tex] is, [tex]3.259\times 10^{-8}mole[/tex]
Explanation :
First we have to calculate the [tex]H^+[/tex] concentration.
[tex]pH=-\log [H^+][/tex]
[tex]10.37=-\log [H^+][/tex]
[tex][H^+]=4.26\times 10^{-11}M[/tex]
Now we have to calculate the [tex]OH^-[/tex] concentration.
[tex][H^+][OH^-]=K_w[/tex]
[tex]4.26\times 10^{-11}\times [OH^-]=1.0\times 10^{-14}[/tex]
[tex][OH^-]=2.35\times 10^{-4}M[/tex]
Now we have to calculate the [tex]Fe^{2+}[/tex] ion concentration.
The balanced equilibrium reaction will be:
[tex]Fe(OH)_2\rightleftharpoons Fe^{2+}+2OH^-[/tex]
The expression for solubility constant for this reaction will be,
[tex]K_{sp}=[Fe^{2+}][OH^-]^2[/tex]
Now put all the given values in this expression, we get:
[tex]1.8\times 10^{-15}=[Fe^{2+}]\times (2.35\times 10^{-4})^2[/tex]
[tex][Fe^{2+}]=3.259\times 10^{-8}M[/tex]
Now we have to calculate the moles of [tex]Fe(OH)_2[/tex].
[tex]\text{Moles of }Fe(OH)_2=\text{Molarity of }Fe(OH)_2\times \text{Volume of solution}[/tex]
[tex]\text{Moles of }Fe(OH)_2=3.259\times 10^{-8}mole/L\times 1L=3.259\times 10^{-8}mole[/tex]
Therefore, the moles of [tex]Fe(OH)_2[/tex] is, [tex]3.259\times 10^{-8}mole[/tex]
The number of moles of Fe(OH)₂ dissolved in 1.0 liter of water buffered at pH = 10.37 is 3.29x10⁻⁸.
The reaction of Fe(OH)₂ solubility in water is:
Fe(OH)₂(s) ⇄ Fe²⁺(aq) + 2OH⁻(aq) (1)
The product of solubility constant for the above reaction is:
[tex] Ksp = [Fe^{2+}][OH^{-}]^{2} = 1.8\cdot 10^{-15} [/tex] (2)
To find the number of moles of Fe(OH)₂ dissolved in the water, we need to find the concentrations of Fe²⁺ and OH⁻.
The OH⁻ concentration can be calculated from the pH:
[tex] pH + pOH = 14 [/tex]
[tex] pOH = 14 - pH = 14 - 10.37 = 3.63 [/tex]
[tex] pOH = -log([OH^{-}]) [/tex]
[tex] [OH^{-}] = 10^{-pOH} = 10^{-3.63} = 2.34 \cdot 10^{-4} M [/tex]
Now, we can find the Fe²⁺ concentration (eq 2)
[tex] [Fe^{2+}] = \frac{Ksp}{[OH^{-}]^{2}} = \frac{1.8\cdot 10^{-15}}{(2.34 \cdot 10^{-4} M)^{2}} = 3.29 \cdot 10^{-8} M [/tex]
The number of moles of Fe²⁺ is:
[tex] n_{Fe^{2+}} = [Fe^{2+}]*V = 3.29 \cdot 10^{-8} mol/L*1.0 L = 3.29 \cdot 10^{-8} \:moles [/tex]
From reaction (1), we have that 1 mol of Fe(OH)₂ produces 1 mol of Fe²⁺, so the number of moles of Fe(OH)₂ is:
[tex] n_{Fe(OH)_{2}} = n_{Fe^{2+}} = 3.29 \cdot 10^{-8} \:moles [/tex]
Therefore, 3.29x10⁻⁸ moles of Fe(OH)₂ will dissolve in 1 liter of water.
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