In the experiment "Preparation and Standardization of a Sodium Hydroxide Solution", why was the burette rinsed with NaOH before filling it to "zero" for the titration?

Answer:

There must be a complete circuit to allow electrons to flow. Oxidation happens at the anode. Reduction happens at the cathode.

Explanation:

Select all that are true for both a voltaic cell and an electrolytic cell.

There must be a complete circuit to allow electrons to flow. YES. This is true for both cells.

The redox reaction is spontaneous. NO. This is only true for the voltaic cell.

Oxidation happens at the anode. YES. This is true for both cells.

Reduction happens at the cathode. YES. This is true for both cells.

The redox reaction is non-spontaneous. NO. This is only true for the electrolytic cell.

The statements that have been true for both voltaic and electrolytic cells are:

Option A: There must be a complete circuit to allow electrons to flow.

Option C: Oxidation happens at the anode.

Option D: Reduction happens at the cathode.

The electrolytic cells are the one that converts electrical energy into chemical energy. Voltaic cells convert chemical energy into electrical energy.

From the given options, the best-suited option for both electrolytic and voltaic cells are:

The statements that have been true for both voltaic and electrolytic cells are, Option A, C, and D.

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Answer:

362g

Explanation:

heat lost by metal= heat gained by acetic acid

tfs are the same so you cando delta T

convert Cal/gc to J/gc

thectgod ig follow

Answer:

True

Explanation:

The value of the mole is equal to the number of atoms in exactly 12 grams of pure carbon-12. 12.00 g C-12 = 1 mol C-12 atoms = 6.022 × 1023 atoms • The number of particles in 1 mole is called Avogadro's Number (6.0221421 x 1023).

Answer:

22.1

Explanation:

Step 1: Calculate the number of formula units of lithium nitrate

A 5.08 L solution contains 2.68 × 10²¹ formula units per liter.

5.08 L × 2.68 × 10²¹ formula units/1 L = 1.36 × 10²² formula units

Step 2: Calculate the number of nitrate ions

Lithium nitrate dissociates completely in water according to the following equation.

LiNO₃(aq) ⇒ Li⁺(aq) + NO₃⁻(aq)

The molar ratio of LiNO₃ to NO₃⁻ is 1:1. The number of nitrate ions is 1/1 × 1.36 × 10²² = 1.36 × 10²².

Then,

log (1.36 × 10²²) = 22.1

The number of nitrate ions are present in the following aqueous solution is 13.6x10²¹, and log(base 10) value of this is 22.2.

Those salts which are completely dissociate into their ions in the solution form will known as strong electrolyte.

Lithium nitrate is a strong electrolyte and it shows complete dissociation as:

LiNO₃ → Li⁺ + NO₃⁻

Given that,

1 liter of solution containing = 2.68 x 10²¹ formula unit

5.08 L of solution containing = 5.08 x 2.68 x 10²¹ = 13.6x10²¹ formula unit

So, number of nitrate ion in given solution = 13.6x10²¹ formula unit

Log(13.6x10²¹) = 22.1

Hence, required values are 13.6x10²¹ and 22.1.

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Answer:

74%

Explanation:

Step 1: Write the balanced equation

2 C₆H₁₀(l) + 17 O₂(g) ⇒ 12 CO₂(g) + 10 H₂O(g)

Step 2: Determine the limiting reactant

The theoretical mass ratio (TMR) of C₆H₁₀ to O₂ is 164:544 = 0.301:1.

The experimental mass ratio (EMR) of C₆H₁₀ to O₂ is 115:199 = 0.578:1.

Since EMR > TMR, the limiting reactant is O₂.

Step 3: Calculate the theoretical yield of H₂O

The theoretical mass ratio of O₂ to H₂O 544:180.

199 g O₂ × 180 g H₂O/544 g O₂ = 65.8 g H₂O

Step 4: Calculate the percent yield of H₂O

%yield = (experimental yield/theoretical yield) × 100%

%yield = (49 g/65.8 g) × 100% = 74%

Answer:

Percentage yield of H₂O = 74.24%

Explanation:

The balanced equation for the reaction is given below:

2C₆H₁₀ + 17O₂ —> 12CO₂ + 10H₂O

Next, we shall determine the masses of C₆H₁₀ and O₂ that reacted and the mass of H₂O produced from the balanced equation. This is can be obtained as follow:

Molar mass of C₆H₁₀ = 82 g/mol

Mass of C₆H₁₀ from the balanced equation = 2 × 82 = 164 g

Molar mass of O₂ = 32 g/mol

Mass of O₂ from the balanced equation = 17 × 32 = 544 g

Molar mass of H₂O = 18 g/mol

Mass of H₂O from the balanced equation = 10 × 18 = 180 g

SUMMARY:

From the balanced equation above,

164 g of C₆H₁₀ reacted with 544 g of O₂ to produce 180 g of H₂O.

Next, we shall determine the limiting reactant. This can be obtained as follow:

From the balanced equation above,

164 g of C₆H₁₀ reacted with 544 g of O₂.

Therefore, 115 g of C₆H₁₀ will react to produce = (115 × 544)/164 = 381 g of O₂.

From the calculations made above, we can see that a higher mass (i.e 381 g) of O₂ than what was given (i.e 199 g) is needed to react with 115 g of C₆H₁₀.

Therefore, O₂ is the limiting reactant and C₆H₁₀ is the excess reactant.

Next, we shall determine the theoretical yield of H₂O. This can be obtained by using the limiting reactant as shown below:

From the balanced equation above,

544 g of O₂ reacted to produce 180 g of H₂O.

Therefore, 199 g of O₂ will react to produce = (199 × 180)/544 = 66 g of H₂O.

Thus, the theoretical yield of H₂O is 66 g.

Finally, we shall determine the percentage yield. This can be obtained as follow:

Actual yield of H₂O = 49 g

Theoretical yield of H₂O = 66 g

Percentage yield of H₂O =?

Percentage yield = Actual yield /Theoretical yield × 100

Percentage yield of H₂O = 49/66 × 100

Percentage yield of H₂O = 74.24%

Answer:

75

Explanation:

is the answer for your question

Solution : An oxidation reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between tow species an oxidaion reductin reaction is any chemical reaction in which the oxidation number of a molecule atom or ion changes by gaining or losing an electron

Explanation:

since hydrochloric acid is an acid and calcium hydroxide is a base, we know that this is an acid base reaction. The ions will then dissociatiate and bond with one another.

Answer:

CaCl2(aq) + Na2CO3(aq) → CaCO3(s) + 2NaCl(aq)

Reference:

H.W. Hanna and A. Dittmar; Laboratory Manual for General Chemistry, 4th ed.; Morton Publishing Company, Denver, Colorado

Answer:

CO

Explanation:

water is known as the mixture

Answer:

iv. Iron

water is not a mixture

hydrogen is the simplest element

air is pure

Answer:

In Haloarenes the C atom to which the X group is attached is SP2 hybridized thus it is become difficult to replace it by the Nucleophile. Since arenes and Vinyl halides are electron rich molecules due to presenceof n bonds, they repel Nucleophile attacking them.

Question:-

Why it is difficult for haloarenes to undergo nucleoplhilic subsituⁿ reaction?

Answer:-

Haloarenes are less reactive towards the nucleoplhilic substitution rxⁿ . This is due to following reasons :-

[tex]\red{\bigstar}\underline{\textsf{ Reason 1 :- Partial double bond character .}}[/tex]

Halogen atom has one lone pair, and due to presence of π - σ - lp , resonance is established in the compound ( see attachment) . Due to resonance there is a partial double bond character in the carbon halogen bond , so it is difficult to break a double bond than a single bond.

[tex]\rule{200}2[/tex]

[tex]\red{\bigstar}\underline{\textsf{ Reason 2 :- $\pi$ cloud .}}[/tex]

When a nucleoplhile comes to attack , it is repelled by the π-cloud of the benzene ring.

[tex]\rule{200}2[/tex]

[tex]\red{\bigstar}\underline{\textsf{ Reason 3 :- Phenyl cation .}}[/tex]

If somehow the halogen atoms leaves the benzene ring ,being more electronegative than carbon , it takes away the electron , thus a positive charge is left on benzene ring and the phenyl cation so formed is very unstable .

[tex]\rule{200}2[/tex]

Explanation:

Physical change

★ Boiling of water

❤︎ freezing of water

❣︎ washing of clothes

♫︎ mixing black and brown stones

Chemical change

➪ making of dough

㋛︎ burning of wood

❥︎ cooking of the raw food

❁ burning of paper

ꨄ︎ rusting of iron

★★★➪➪➪➪ it was help to you

Answer:

[tex]{ \sf{Ca _{3} P_{2} }}[/tex]

Answer:

13.5%

Explanation:

To answer this you need to understand that percentage error can never be negative as we use absolute value in the equation

To get molar/atomic mass = mass/moles

=0.3681g/(6.514×10^-3)moles

=56.509g/moles

percentage error = (65.38-56.509)/65.38 ×100

=13.56% (this is what I'm getting without rounding off your question wasn't specific on how many d.p to use)

Answer:

XCH₄ = 0.461

XCO₂ = 0.539

Explanation:

Step 1: Given data

Step 2: Calculate the total pressure in the container

We will sum both partial pressures.

P = pCH₄ + pCO₂

P = 431 mmHg + 504 mmHg = 935 mmHg

Step 3: Calculate the mole fraction of each gas

We will use the following expression.

Xi = pi / P

XCH₄ = pCH₄/P = 431 mmHg/935 mmHg = 0.461

XCO₂ = pCO₂/P = 504 mmHg/935 mmHg = 0.539

Answer:

C . Kinetic Molecular Theory

Answer:

2) 3 carbons

Explanation:

The alkane with one carbon is methane but it has no isomer.

The alkanes starting with propane only have isomers

Explanation:

An alkane can show structural isomerism if it has at least __4__ carbon atom

Answer:

On moving from left to right in a period the electropositive character decreases as the tendency to lose electrons decreases.

Explanation:

Answer:

A

Explanation:

uptakw of raduoactive iofine by the thyroid gland js measurd

Answer:

It obeys rule

Explanation:

Benzene is an aromatic hydrocarbon because it obeys Hückel's rule.

Answer:

Benzene is an aromatic compound because it is planar, cyclic, conjugated and has (4n +2) π electrons, where n= 1.

Explanation:

Hückel's rule states that a molecule is aromatic if it is planar, cyclic, conjugated and has (4n +2) π electrons.

Breaking it down into 4 requirements, we have:

Let's look at each of the 4 parts!

What is planar?

Planar refers to the molecule being flat. When an atom is sp² hybridized, it is in a trigonal planar geometry. Let's look at the benzene molecule. Each carbon is attached to 3 other atoms, namely 2 carbons and 1 hydrogen. This means that each carbon is sp² hybridized, making the molecule planar.

Cyclic

This refers to the molecule having a closed ring shape. Benzene fulfils this criteria.

Conjugation

This refers to a system of connected p orbitals, which allows π electrons to delocalize. Each carbon atom in benzene has one 2p orbital, making benzene a conjugated molecule. For molecules that are not cations or anions, conjugated molecules are those that have alternating single and double bonds.

(4n +2) π electrons

n is an integer (e.g. 0, 1, 2, 3) thus for the molecule to be aromatic, it can have 2, 6 or 10 π electrons (non exhaustive). This separates an aromatic compound from an antiaromatic compound, which has 4n π electrons instead.

Benzene has 6 π electrons, so n has a value of 1 in this case.

Thus, benzene is an aromatic compound because it is planar, cyclic, conjugated and has (4n +2) π electrons.

_______

Counting the number of π electrons

Let's look at π bonds!

A double bond is made up of 1 σ bond and 1 π bond, and each π bond is made up of 2 π electrons. We do not count the number of single bonds since single bonds are made up of 1 σ bond only.

There are 3 double bonds in the Kekulé structure of benzene. Thus, the number of π electrons in benzene is 3(2)= 6.

Attached diagrams

Answer:

deuterium is heavier isotope of hydrogen need

high weight of atom will lead to higher boiling point

Answer:

The independent variable of an experiment is the one that is intentionally changed or manipulated to see the results of changing said variable.

We are told that in each different group, the amount of caffeine that is given to the dog's changes - in the control group, they get no caffeine, in the 2nd group, they get 10 mg of caffeine each, and in the 3rd group, they get 50 mg of caffeine each.

Therefore, since the amount of caffeine that is given to the dogs is the only variable that is being manipulated, this is the independent variable.

Answer: The independent variable of an experiment is the one that is intentionally changed or manipulated to see the results of changing said variable.

The independent variable of an experiment is the one that is intentionally changed or manipulated to see the results of changing said variable.

We are told that in each different group, the amount of caffeine that is given to the dog's changes - in the control group, they get no caffeine, in the 2nd group, they get 10 mg of caffeine each, and in the 3rd group, they get 50 mg of caffeine each.

Therefore, since the amount of caffeine that is given to the dogs is the only variable that is being manipulated, this is the independent variable.

We are told that in each different group, the amount of caffeine that is given to the dog's changes - in the control group, they get no caffeine, in the 2nd group, they get 10 mg of caffeine each, and in the 3rd group, they get 50 mg of caffeine each.

Therefore, since the amount of caffeine that is given to the dogs is the only variable that is being manipulated, this is the independent variable.

Explanation:

In the original solution you have the mixture of a weak acid (Hypochlorous acid) and its conjugate base (Sodium hypochlorite). That is a buffer.

The barium hydroxide will react with hypochlorous acid. If this reaction cause the complete reaction of hypochlorous acid, the buffer break its capacity and the pH change in several units. In this case:

The addition of barium hydroxide will raise the pH slightly because the buffer still working.

The initial moles of those species are:

Hypochlorous acid:

[tex]1L * \frac{0.370mol}{1L} = 0.370 moles[/tex]

Sodium hypochlorite:

[tex]1L * \frac{0.493mol}{1L} = 0.493 moles[/tex]

Now, a strong acid as barium hydroxide (Ba(OH)₂) reacts with a weak acid as hypochlorous acid (HClO) as follows:

Ba(OH)₂ + 2HClO → Ba(ClO)₂ + 2H₂O

For a complete reaction of 0.092 moles of barium hydroxide are required:

[tex]0.092 moles Ba(OH)_2*\frac{2mol HClO}{1molBa(OH)_2} = 0.184 moles HClO[/tex]

As there are 0.370 moles, the moles of HClO after the reaction are:

0.370 moles - 0.184 moles = 0.186 moles of HClO will remain

As you still have hypochlorite and hypochlorous acid you still have a buffer.

Thus, the pH will raise slightly because the amount of acid is decreasing and slightly because the buffer can keep the pH.

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Answer:

Both have solutions in the  graduated cylinder.

Explanation:

Recording the amount of alcohol used as the difference between two masses is the wrong method used for measuring tert-butyl alcohol for the experiment.  For measuring tert-butyl alcohol for this experiment, the student has to measure the two masses when both the graduated cylinders has solution of tert-butyl alcohol not when one of it is empty (having no tert-butyl alcohol ).

The wrong aspect is that the liquid didn't need to be weighed. Instead the volume should have been recorded with the aid of the graduated cylinder.

This is a cylinder with marked readings and is used to measure the volume of liquids in the laboratory.

The graduated cylinder will accurately measure the amount of  alcohol used due to it being volatile and the mass fluctuating during the measurement.

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Answer:

See explanation and Image attached

Explanation:

The preparation of triphenylmethanol occurs as shown in the image attached to this answer.

The first step is the nucleophillic reaction of the phenyl magnesium bromide with the carbonyl group.

Reaction of the second molecule of phenyl magnesium bromide with the product yields triphenyl methoxide ion. Reaction with acid yields the triphenylmethanol product which is extracted into the organic phase.

The triphenylmethanol product can be purified by recrystallization.

Explanation:

one thing to know is that higher surface area = higher boiling point.

NaCl has the smallest surface area, so it's the first one.

H2O has less surface area than methane, so it's second.

Methane has more surface area than H20, so it's third.

The big molecule has the most surface area, so it's last

Temperature measures the average kinetic energy of particles of the substances. Melting point is directly proportional to surface area. Therefore, the correct option is option C.

Temperature is used to measure degree or intensity of heat of a particular substance. Temperature is measured by an instrument called thermometer.

Temperature can be measured in degree Celsius °c, Kelvin k or in Fahrenheit. Temperature is a physical quantity. Heat always flow from higher temperature source to lower temperature source.

We can convert these units of temperature into one another. The relationship between degree Celsius and Fahrenheit can be expressed as:

°C={5(°F-32)}÷9

Melting point is directly proportional to surface area. NaCl has the smallest surface area. Water has less surface area than methane. Methane has more surface area than H[tex]_2[/tex]O.

Therefore, the correct option is option C.

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