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2 years ago

4-hydroxypentanal reacts with one equivalent of methanol to form a cyclic acetal.

Chemistry

1 answer:

quester [9]2 years ago

4 0

Answer:

Explanation:

The equation is given as:

CH3CHOHC2H4CHO + CH3OH --> CYCLIC ACETAL + H2O

This above equation is carried out in the presence of a strong acid. There are five mechanisms employed and they are:

Step 1:

Initial formation of the hemiacetal which takes several steps

Step 2:

Addition of a proton. The hemicetal is protonated on the hydroxyl group (-OH group)

Step 3:

As seen a bond is broken to give the H2O molecule and a resonance stabilized cation.

The carbonyl group on the cation is enriched with the oxygen-18 got from the H2O molecule as seen in the mechanism.

Step 4:

An attraction occurs between electrophile and nucleophile i.e the stabilised cation and the lone paids of the methanol.

Step 5:

Finally, a proton (+) is removed from the molecule by a lone pair of electron on the methanol.

Attached are the Steps 1 - 5 mechanism below

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Which one of the following statements BEST describes a chemical reaction?

Natalija [7]

Answer: The correct statement is (A new substance is formed and the process can usually NOT be undone.)

Explanation:

A chemical reaction is simply defined as the reaction between two or more elements in which a new substance is formed and the process can usually not be undone. Different types of chemical reaction includes:

-- combination reaction: this occurs when two or more reactants form a product. For example: In the burning of coal, It combines with oxygen to produce carbon dioxide. Also in the burning of wood, carbon dioxide is given off and ashes are formed. Because new substance is being formed, they often can't be undone. The ashes formed can't be changed back into wood. Other types of chemical reaction are listed below.

-- Decomposition reaction

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For the product of a chemical reaction to be undone (reversed), it has to undergo another chemical process different from the one that produced it.

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2 years ago

What average global temperature is maintained when there is a balance in Earth’s energy budget?

Thepotemich [5.8K]

The incoming and outgoing energy at the Earth’s surface must balance. Or in other words, the flow of energy into the atmosphere must be balanced by an equal flow of energy out of the atmosphere and back to space.
Earth's Energy balance describes how the incoming energy from the sun is used and returned to space. All of the energy entering earth’s atmosphere comes from the sun. Half of it is absorbed by the earth’s surface i.e. the land and oceans, 30% is directly reflected back to space by clouds and 20% is absorbed by the atmosphere and clouds.Earth's actual average global temperature is around 14° C (57 F).

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2 years ago

Read 2 more answers

The complete combustion of propane (C3H8) in the presence of oxygen yields CO2 and H2O: C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (g) a

mixas84 [53]

Answer:

26.9 L is the volume of CO₂, we obtained

Explanation:

The reaction is: C₃H₈(g) + 5O₂(g) → 3CO₂ (g) + 4H₂O (g)

Let's determine the reactants moles:

27.5 g . 1mol / 44 g = 0.625 moles

We need density of O₂ to determine mass and then, the moles.

O₂ density = O₂ mass / O₂ volume

O₂ density . O₂ volume = O₂ mass

1.429 g/L . 45L = O₂ mass → 64.3 g

Moles of O₂ → 64.3 g . 1mol/32g = 2.009 moles

Let's find out the limiting reactant:

1 mol of propane needs 5 moles of oxygen to react

Then, 0.625 moles will react with (0.625 . 5)/1 = 3.125 moles of O₂

Oxygen is the limiting reactant, we need 3.125 moles but we only have 2.009 moles

Ratio is 5:3. 5 moles of O₂ produce 3 moles of CO₂

Therefore, 2.009 moles of O₂ must produce (2.009 .3) /5 = 1.21 moles of CO₂. Let's find out the volume, by Ideal Gases Law (STP are 1 atm and 273K, the standard conditions)

1 atm . V = 1.21 moles . 0.082 . 273K

V = (1.21 moles . 0.082 . 273K) / 1atm = 26.9 L

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3 years ago

Cathode-electrolyte interphase in lithium batteries revealed by cryogenic electron microscopy. matte

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Cryo-EM is used to preserve and characterize cycled positive electrodes. Under regular cycling conditions, there isn't an intimate coating layer like CEI.A small electrical short can cause a stable conformal CEI to form in place. The conformal CEI's chemistry is revealed by EELS and cryo-(S)TEM.

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1 year ago

are either positively charged or negatively charged species in which the number of protons and electrons are not equal. ________

fredd [130]

Answer:

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3. The positively charged ions are called cations, which comprise more protons than electrons.

4. An example of a polyatomic anion is the hydroxide anion.

5. The system of assigning an unambiguous name to a compound is called nomenclature.

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2 years ago