27.8 mL solution of 0.797 M HCHO2 with 0.928 M NaOH. What is the pH for the solution at the equivalence point in the titration?

Answers

Answer 1

Answer:

8.69 is the pH at the equivalence point

Explanation:

Formic acid, HCHO₂, reacts with NaOH as follows:

HCHO₂ + NaOH → NaCHO₂ + H₂O.

At the equivalence point you will have in the reaction just NaCHO₂ and H₂O. The concentration of NaCHO₂ will be:

Moles: 0.0278L * 0.797mol/L = 0.02216moles

To reach the equivalence point it is necessary to add:

0.02216mol * (1L / 0.928mol) = 0.0239L

Total volume in the equivalence point:

0.0278L + 0.0239L = 0.0517L

Concentration: 0.02216moles / 0.0517L = 0.429M

The equilibrium of NaCHO₂, CHO₂⁻, in water is:

CHO₂⁻(aq) + H₂O(l) ⇄ OH⁻(aq) + HCHO₂(aq)

Where Kb, 5.56x10⁻¹¹ is defined as:

5.56x10⁻¹¹ = [OH⁻] [HCHO₂] / [CHO₂⁻]

In the equilibrium, it is produced X OH⁻ and HCHO₂, and as concentration of NaCHO₂ is 0.429M:

5.56x10⁻¹¹ = [X] [X] / [0.429M]

2.383x10⁻¹¹ = X²

4.88x10⁻⁶ = X = [OH⁻]

As pOH = -log [OH⁻]

pOH = 5.31

And pH = 14 - pH

pH = 8.69 is the pH at the equivalence point


Related Questions

The potential energy of a roller coaster is 50 joules. The kinetic energy of the same coaster is 50 joules. What is the mechanical energy of the coaster? O joules 50 joules 100 joules​

Answers

Answer:

100 joules​

Explanation:

The mechanical energy (M.E) of an object describes the objects ability to do work. The mechanical energy encompasses the object's energy due to its position (potential energy) and its energy due to motion (kinetic energy).

Therefore,

M.E = K.E + P.E

According to this question, potential energy (P.E) of the roller coaster is 50J and the kinetic energy (K.E) is also 50J. Hence, the mechanical energy (M.E) is

M.E = 50J + 50J

M.E = 100J

If the P.E and K.E of a roller coaster is 50 Joules respectively, the mechanical energy of the roller coaster is 100 Joules.

Given the following data:

Potential energy of roller coaster = 50 Joules.Kinetic energy of roller coaster = 50 Joules.

To find the mechanical energy of the roller coaster:

The mechanical energy of a physical object or body is the total sum of the potential energy (P.E) and kinetic energy (K.E) possessed by an object.

Mathematically, mechanical energy is given by the formula;

Substituting the given parameters into the formula, we have;

[tex]M.E = 50 + 50[/tex]

Mechanical energy (M.E) = 100 Joules.

Therefore, the mechanical energy of the roller coaster is 100 Joules.

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2 2 6 2 6 2 10 3
1s 2s 2p 3s 3p 4s 3d 4p
=

Answers

Answer:

ARSENIC

Explanation:

It has an atomic number of 33

In carbon dioxide (CO2), there are two oxygen atoms for each carbon atom. Each oxygen atom forms a double bond with carbon, so the molecule is formed by two double bonds.

Two double bonds means that the total number of electrons being shared in the molecule is

Answers

Answer:

The Answer is eight.

Explanation:

Sorry if it's too late and it doesn't help! But I hope you have a magnificent day! :3

Answer:

8

Explanation:

I had this question on my quiz and got it right.

A student measured the masses of four different-sized blocks. The student determined that each block had a mass of 50 grams.


(There is a small block, a little bit bigger block, a big block and the biggles block)


Which block has the least density?

Answers

Answer:..

Explanation:

The atom is neutral because
(10 Points)
O protons
neutrons
O
electrons =neutrons
protons -electrons
O nucleus = electron
Y

Answers

Protons and electrons are equal

Answer:

the answer is B

Explanation:

When an atom has an equal number of electrons and protons, it has an equal number of negative electric charges

Please I need help with this

Answers

Answer: put 45 mm

Explanation:

Assume that silver and gold form ideal, random mixtures. Calculate the mass of pure Ag needed to cause an entropy increase of 20 J/K when mixed with 100g of pure Au

Answers

Answer:

[tex]m_{Ag}=2,265.9g[/tex]

Explanation:

Hello!

In this case, since the definition of entropy in a random mixture is:

[tex]\Delta S=-n_TR\Sigma[x_i*ln(x_i)][/tex]

For this silver-gold mixture we write:

[tex]\Delta S=-(n_{Au}+n_{Ag})R\Sigma[\frac{n_{Au}}{n_{Au}+n_{Ag}} *ln(\frac{n_{Au}}{n_{Au}+n_{Ag}} )+\frac{n_{Ag}}{n_{Au}+n_{Ag}} *ln(\frac{n_{Ag}}{n_{Au}+n_{Ag}} )][/tex]

By knowing the moles of gold:

[tex]n_{Au}=100g*\frac{1mol}{197g} =0.508mol[/tex]

It is possible to write the aforementioned formula in terms of the variable [tex]x[/tex] representing the moles of silver:

[tex]20\frac{J}{mol}=-(0.508+x)8.314\frac{J}{mol*K} \Sigma[\frac{0.508}{0.508+x} *ln(\frac{0.508}{0.508+x} )+\frac{x}{0.508+x} *ln(\frac{x}{0.508+x} )][/tex]

Which can be solved via Newton-Raphson or a solver software, in this case, I will provide you the answer:

[tex]x=n_{Ag}=21.0molAg[/tex]

So the mass is:

[tex]m_{Ag}=21.0mol*\frac{107.9g}{1mol}\\ \\m_{Ag}=2,265.9g[/tex]

Best regards!

Select the word that is incorrect in the paragraph and replace it with a word which makes the statement correct:
Group 2 elements have two valence electrons in their outer shell and are considered metals. In order to form an ion, a Group 2 element will
gain two electrons and form a cation.

Answers

A group 2 element will lose two electrons and form an anion.

Ions can be made by single element or covalently bonded group of elements. The covalently bonded group of elements is called polyatomic ions or polyatomic atoms. In order to form an ion, a Group 2 element will loose two electrons and form a cation.

What is Ions?

Any species that contain charge whether it is positive charge or negative charge is called ions. The example of polyatomic ions are sulfate, phosphate, nitrate etc.

Cation is the species that loose electron and attain positive charge while anion is a species which gain electron and attains negative charge so when anion and cation combine in fixed ration the the overall charge of the molecule is zero that is molecule is neutral, the charge over cation and anion is also called oxidation state.  In order to form an ion, a Group 2 element will loose two electrons and form a cation.

Therefore, in order to form an ion, a Group 2 element will

loose two electrons and form a cation.

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Hydrogen sulfide decomposes according to the following reaction, for which Kc=9.30E-8 at 700 degrees Celsius. 2 H2S(g) --> 2 H2(g) + S2(g) If 0.29 moles of H2S is placed in a 3.0-L container, What is the equilibrium concentration of H2(g) at 700 degrees Celsius?

Answers

Answer: The equilibrium concentration of [tex]H_2(g)[/tex] at 700 degrees Celsius is 0.0012 M

Explanation:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as [tex]K_c [/tex]

Moles of  [tex]H_2S[/tex] = 0.29 mole

Volume of solution = 3.0 L

Initial concentration of [tex]H_2S[/tex] = [tex]\frac{0.29mol}{3.0L}=0.097M[/tex]

The given balanced equilibrium reaction is,

                    [tex]2H_2S(g)\rightleftharpoons 2H_2(g)+S_2(g)[/tex]

         Initial conc.         0.097 M           0M          0M

At eqm. conc.    (0.097-2x) M            (2x) M   (x) M

The expression for [tex]K_c[/tex] is written as:

[tex]K_c=\frac{[H_2]^2\times [S_2]}{[H_2S]^2}[/tex]

[tex]K_c=\frac{(2x)^2\times x}{(0.097-2x)^2}[/tex]

[tex]9.30\times 10^{-8}=\frac{(2x)^2\times x}{(0.097-2x)^2}[/tex]

[tex]x=0.00060[/tex]

Equilibrium concentration of [tex][H_2][/tex]= 2x= [tex]2\times 0.00060=0.0012M[/tex]

if u trust urself do it
Study these images.

4 photos of clouds. 1: Sky covered with large, flat layers of blue, grey clouds. 2: A tall, fluffy cloud shaped like an anvil. 3: Round, puffy clouds in a blue sky. 4: Thin, wispy clouds high in the sky.

Which image shows a cumulonimbus cloud?

1
2
3

Answers

Answer:

3

Explanation:

I wish you the best, its three or 2

Answer:

2

Explanation:

Edge 2021

(a) Write a briefexperimental procedure for the chromic acid test.Include all observations such ascolor change, precipitation, etc.(5 points)(b) What functional groups can be distinguished by this test?(2points)(c) What is the reason for the color change if you get a positive chromic acid test?(3points)(d) Sketch a reaction mechanism for a positive chromic acid test with the above given molecules.(10points) g

Answers

Answer:

See explanation

Explanation:

a) -About 1-2 drops of the unknown is dissolved in approximately 1 mL of analytical grade acetone standard solution. The test solution is added and shaken thoroughly.  If a positive test is not immediately observed, the set should be allowed to stand for 1-2 minutes. A positive result means the appearance of a green color.

b) The functional groups that can be distinguished by the test are alcohols and aldehydes.

Aldehydes give a positive test to chromic acid but ketones do not.

Primary and secondary alcohols give a positive test to chromic acid but tertiary alcohols do not.

c) Chromic Acid Test involves Cr in the +6 oxidation state. A positive test implies the reduction of orange Cr^6+ to green chromium Cr^3+.

d) The compounds were not shown but this image attached from lumen learning summarizes the reaction mechanism of chromic acid test.

The system is originally at equilibrium with [butane] = 1.0 M and [isobutane] = 2.5 M.If 0.50 mol/L of isobutane is suddenly added and the system shifts to a new equilibrium position, what is the equilibrium concentration of butane?

Answers

Answer:

1.14 M

Explanation:

Let's consider the following reaction.

butane ⇄ isobutane

We can use the concentrations at equilibrium to calculate the equilibrium constant.

Kc = [isobutane] / [butane]

Kc = 2.5 / 1.0

Kc = 2.5

If we add 0.50 M of isobutane, we get [isobutane] = 2.5 + 0.50 = 3.0 M.

This will be an initial concentration in an ICE chart.

        butane ⇄ isobutane

I           1.0              3.0

C         +x                -x

E        1.0+x           3.0-x

The equilibrium constant is:

Kc = 2.5 = [isobutane] / [butane]

2.5 = (3.0-x) / (1.0+x)

2.5 + 2.5x = 3.0-x

x = 0.14

The equilibrium concentration of butane is:

[butane] = 1.0+x = 1.14 M

In which of the following atoms are valence electrons in the lowest average potential energy states?

Cl
Br
F
I

Answers

Answer:

C) F

Explanation:

Valence electrons are the electrons present in the outermost shell of an atom and have the highest energy level of an atom whereas electrons at ground state or lower orbitals have less potential energy.

This is so because orbitals nearby nucleus are strongly bonded with the atomic nucleus and have less energy than an outermost shell.

So, the potential energy states of an atom depend on the number of orbitals. In the given options fluorine with atomic number 9 has less number of orbitals that is 2 orbitals and valence electrons will be present in second orbitals, so fluorine will have the lowest average potential energy states.

Hence, the correct option is "C) F".

the isotopes of an elements have the same masse

Answers

Answer:

True

Explanation:

But have different neutrons

My made-up polyatomic ion goldate acts a lot like chlorate (it has the same charge and the same number of oxygens). What would the name be for the acid, HG004(aq)?
a. Hydrogen diogoldate
b. Goldous acid
c. Goldic acid
d. Pergoldic acid
e. None of these

Answers

Answer:

d. Pergoldic acid

Explanation:

chlorate = ClO₃⁻

Goldate GoO₃⁻

On this basis we can infer that HClO₄ and HGoO₄ will be similar .

HClO₄ is called perchloric acid , hence HGoO₄ will be called pergoldic acid.

Writing key words in the margin is part of which note-taking procedure?

Select one:
a. record
b. review
c. reduce
d. recite

Answers

Reduce = writing key words as cue words AFTER a lecture. Record = DURING a lecture, write meaningful info. I believe your answer would be C “reduce”. Hope this helps!

Which statements best describe half lives of radioactive isotopes

Answers

You should also add the statements

Answer:

The half-life varies depending on the isotope.

Half-lives range from fractions of a second to billions of years.

The half-life of a particular isotope is constant.

Explanation:

Make sure you add the options

Entropy is a measure of
1.
accuracy
2.
precision
3.
the disorder of a system
4.
the attraction of a nucleus for an electron

Answers

Answer:

The answer is actually 3. The disorder of a system.

Observing a phenomenon in the lab includes which of the following?

Throwing away irrelevant items

Sorting through and disposing of police reports

Collecting evidence

Identifying unique features of evidence

Answers

Answer:

D

Explanation:

Identifying unique features of evidence

A laboratory is a place where scientific investigations and experiments are conducted. Observing a phenomenon in the lab includes identifying unique features of evidence. Thus, option D is correct.

What is observation?

An observation is said to be the deduction that is seen or heard and is due to the actions of the process or event that are gained from the information from a conducted experiment.

It is an important factor in an experiment and research and is used in the lab to falsify or prove the hypothesis. It is made based on the experimental setup and involves various steps.

The observations are used to draw conclusions and inferences based on the detailed identification of the characteristics of the evidence. The evidence supports the observation.

Therefore, option D. the features of evidence are the correct option.

Learn more about observations here:

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A solution is made by mixing of 42.g water and 77.g of acetic acid HCH3CO2. Calculate the mole fraction of water in this solution.

Answers

Moles of [tex]H_2O[/tex] ,

[tex]n_{H_2O}=\dfrac{42}{2\times 1 + 16}=\dfrac{42}{18}\\\\n_{H_2O}=2.33\ moles[/tex]

Moles of acetic acid [tex]HCH_3CO_2[/tex] ,

[tex]n_{A.A}=\dfrac{77}{1 + 12 + 3 + 12 + 16\times 2}=\dfrac{77}{60}\\\\n_{A.A}=1.28\ moles[/tex]

Mole fraction of water :

[tex]M.F_{H_2O}=\dfrac{n_{H_2O}}{n_{H_2O}+n_{A.A}}\\\\M.F_{H_2O}=\dfrac{2.33}{2.33+1.28}\\\\M.F_{H_2O}=0.645[/tex]

Therefore, mole fraction of water in this solution is 0.645 .

Hence, this is the required solution.

The Earth can gain or lose matter. True False​

Answers

Answer:

True

Explanation:

According to some calculations, the Earth is losing 50,000 metric tons of mass every single year, even though an extra 40,000 metric tons of space dust converge onto the Earth's gravity well, it's still losing weight.

Answer:

true

Explanation:

what is the first step in the scientific inquiry process​

Answers

Answer:

make an observation that describes a problem

Explanation:

Answer:

The first step in the Scientific Method is to make objective observations.

Explanation:

....-

Which graph best matches a person walking away at a constant speed

Answers

A graph with a line that stays the same


1. What 2 subatomic particles have charges? List the particle name and its charge.

Answers

Answer: Proton - positive charge (+)

Neutron - neutral charge (0)

Electron - negative charge (-)

Explanation:

What specific portion of the gill is used to increase surface area though which gas (oxygen and carbon dioxide) exchange take place?

Answers

Answer:

gill lamellae

Explanation:

Gills  in fishes are structures that permit fish to carry out gaseous exchange in water.  Fishes exchange gases  such as oxygen and carbon dioxide using gills.

Fish gills carry out their activity mainly through its major component called the  gill lamellae. These are comb-like filaments which help increase the surface area of the gills in order to facilitate gaseous exchange

A balloon contains 1.1 L of gas at a pressure of 0.80 atm. How will the volume
change if the pressure is increased to 2.0 atm?

Answers

Answer:

Final volume  = 0.44 L

Explanation:

Given data:

Initial volume of balloon = 1.1 L

Initial pressure = 0.80 atm

Final volume = ?

Final pressure = 2.0 atm

Solution:

The given problem will be solved through the Boly's law,

"The volume of given amount of gas is inversely proportional to its pressure by keeping the temperature and number of moles constant"

Mathematical expression:

P₁V₁ = P₂V₂

P₁ = Initial pressure

V₁ = initial volume

P₂ = final pressure

V₂ = final volume  

Now we will put the values in formula,

P₁V₁ = P₂V₂

0.80 atm × 1.1 L = 2.0 atm × V₂

V₂ = 0.88 atm. L/ 2.0 atm

V₂ = 0.44 L

Quickly please! Which is a group of tissues that work together to carry out a common function?

cell
organ
organelle
organ system

Answers

Answer:

organ system

Explanation:

Answer:

B) organ

Explanation:

Describe three factors that could limit the growth of the prairie dog population

Answers

Answer:

Changes in environment, food source changes and disease?

Explanation:

I dont know what the answer choices are

Answer:

changes in the environment

Explanation:

like digging big holes.

Hope this helps!

What do scientists call all of the compounds that contain carbon and are found in living things?

organic
inorganic
acidic
nonacidic

Answers

Organic is the answer

Answer:

Organic

Explanation:

Edge student

In science class, a student is given a copper cylinder to investigate. The student measures the mass of the cylinder as 53.76 grams. The
student measures the volume of the copper as 6 cm. Which additional property of the copper can the student determine from these
measure

Answers

Answer:

From these two values, i.e. mass and volume, density of the copper cylinder can be calculated.

Formula of density is :

Density = Mass / volume.

Now we have mass: 53.76g and volume 6cm³

Density = 53.76 / 6

Density= 8.96 g/cm³

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