Why is sublimation an effective technique for the isolation of pure caffeine?
Select one or more:
O The impurities of caffeine synthesis are expected to decompose at high temperatures.
O The purified caffeine will vaporize and can be collected as a solid, leaving impurities behind.
O When heated, caffeine will sublime at a lower temperature than it melts.
O The synthesis of caffeine tends not to produce impurities, so a more thorough purification technique is not needed.

Answer:

The water cycle, also known as the hydrologic cycle or the hydrological cycle, describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly constant over time but the partitioning of the water into the major reservoirs of ice, fresh water, saline water and atmospheric water is variable depending on a wide range of climatic variables. The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow. In doing so, the water goes through different forms: liquid, solid (ice) and vapor. Hope this helps, mark as brainliest please!

Answer:

The correct answer is B. Liquids have less energy than solids.  This is false because liquids have more energy than solids; the particles in a liquid are moving whereas the particles in a solid are almost still (they may vibrate slightly).  This increase in speed of particles translates to kinetic energy, showing us that liquids have more energy than solids.

Explanation:

We can also examine the other answer choices and show why they are incorrect.

Solids have a definite volume and shape.  Think about solids in your house; for example, think about a chair or a block.  The shape of these items cannot be changed, and their volume is unchanging.

There are no intermolecular forces between the particles of a gas. This is assumed to be a property of an ideal gas, which makes sense since the particles in a gas are farther from each other than those in a liquid or a solid.'

Sublimation occurs when a solid turns into a gas.  This is also a true statement; when a solid sublimes, it changes into a gas without ever becoming a liquid.

Hope this helps!

Concentrated H2SO4 should always be added to H2O because water is less reactive and acts as a diluent, while adding water to acid can lead to a violent exothermic reaction.

Concentrated H2SO4 and water react exothermically, meaning they release heat during the mixing process. This is due to the highly concentrated acid's strong affinity for water. If water were added to concentrated acid, the heat released would be localized and concentrated in a small volume, leading to a sudden and potentially violent reaction. The rapid generation of heat can cause the mixture to boil or splatter, posing a significant safety risk.

However, when concentrated H2SO4 is added slowly to water while stirring, the heat generated is distributed more evenly throughout the mixture. This gradual addition allows for better heat dissipation and minimizes the chances of splattering or boiling. By following the "add acid to water" approach, the reaction can be controlled more effectively, reducing the risk of accidents and creating a safer working environment.

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Let's see

\(\\ \rm\rightarrowtail H_2+S=H_2S+Heat\)

So

Observe the equation

it releases heat means it's exothermic

So

Two possible sources of systematic (determinate) error in the experiment are; Incorrect calibration of volumetric glasswareIncorrect mass of NaCl

To calculate the concentration of NaCl in the resulting solution in mg/L NaCl, we can use the formula; Concentration (mg/L) = (Mass of solute ÷ Volume of solution in L) × 1000 g / 1 mg NaCl is present in the stock solution of 25 mL. So, the mass of NaCl in the solution would be;0.0842 g ÷ 25 mL = 0.00337 g/mL. Now, in the resulting solution, a 1.00 mL aliquot of the stock solution is transferred to a 50.00 mL volumetric flask and diluted to volume. Therefore, the volume of the resulting solution is 50.00 mL. We will substitute these values in the formula, Concentration (mg/L) = (0.00337 g/mL ÷ 50 mL) × 1000 g / 1 mg concentration (mg/L) = 67.4 mg/L. Therefore, the concentration of NaCl in the resulting solution in mg/L NaCl is 67.4 mg/L.7.  Concentration = 67.4 mg/LTolerance = 4.28 mg/LTotal concentration = 67.4 + 4.28 mg/L = 71.68 mg/LWe round off this value to one decimal place; Total concentration = 71.7 mg/LTherefore, the concentration of NaCl in the resulting solution using propagation of error through the calculation is 67.4+0.4 mg/L.8. Two possible sources of random (indeterminate) error in the experiment are; Errors in temperature measurement. Errors in measurement of water volume. Two possible sources of systematic (determinate) error in the experiment are; Incorrect calibration of volumetric glasswareIncorrect mass of NaCl.

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The Alien Death Moon is an enigmatic and powerful cosmic entity that has the ability to alter the trajectories of objects in its vicinity.

What do you mean by trajectories?

Trajectories refer to the path that an object takes over a period of time. This can refer to the physical path of an object moving in space or the path of an object's energy, such as the path of sound through a speaker. Trajectories can also refer to the path of a person's life, such as the trajectory of their career or life decisions.

Its gravitational pull is so strong that it is able to redirect the paths of objects that come close to it, including the Space Station's probe. The sudden change in the probe's direction is an indication that it has been affected by the Alien Death Moon's gravitational pull, prompting the crew to suspect its presence.

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Answer:

B is correct answer because The enthalpy is negative so this means the reaction produces heat and the reaction is exothermic

Answer:

nonpolar

Explanation:

A nonpolar solvent has the highest solubility with a nonpolar solute.

A substance composed of atoms of more than one element that are held together by chemical bonds is called a compound. Therefore the correct option is option A.

A compound is a pure material that is created by chemically combining two or more distinct components in a specific order. Chemical bonds, which can be ionic or covalent, hold the atoms of a substance together.

The characteristics of compounds are distinct from the characteristics of the constituent parts.

For instance, sodium is a soft metal and chlorine is a greenish-yellow gas; nevertheless, when these two elements combine to produce sodium chloride (table salt), they create a white crystalline solid that is far more stable than the constituent parts of each element alone. Therefore the correct option is option A.

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Answer:

Synthesis

Explanation:

Decomposition is where one compound splits into two or more

Single replacement is when an element switches with another element in a compound

Combustion is when something combines with oxygen to produce water and carbon dioxide

Double replacement is like single but two compounds switch their elements

The picture that correctly shows the path of the reflected light ray is: Picture A.

A ray diagram can be defined as the graphical representation of the possible paths that a light wave takes from one point (source) to another.

Basically, some of the phenomenon and properties associated with light ray include the following:

A reflected light ray completely bounces off a surface and as such, light wave do not pass through the surface as illustrated in Picture A.

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Answer:

N2 + H2 ----------》NH3

On balancing it

N2. + 3.H2------->2.NH3

( 1 mol) (3 mol) (2 mol)

1 mol of nitrogen reacts with 3 mol of hydrogen to give 2 mol of ammonia.

Likewise,

20 litres of nitrogen reacts with 60 litres of hydrogen to give 40 litres of Ammonia.

Hence, the answer is 40 Litres.

There is 22.4 L in one mole

14 moles of CO2

1.25 moles of oxygen

The mole is a unit of measurement used in chemistry to express the amount of a substance. One mole of a substance is defined as the amount of that substance that contains the same number of entities, such as atoms, molecules, or ions, as there are in 12 grams of carbon-12. This number is approximately 6.02 x 10^23 entities and is known as Avogadro's number.

If 1 mole of methane produces 2 moles of CO2

7 moles of methane will produce 7 * 2 /1

= 14 moles of CO2

If 2 moles of oxygen combusts 1  mole of methane

2.5 moles of oxygen will combust 2.5 * 1/2

= 1.25 moles

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The pressure of the nitrogen gas would need to decrease to 3.94 atm in order for the volume to increase to 10.90 L, assuming constant temperature and ideal behavior.

To solve this problem, we can use the ideal gas law equation: PV = nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is the temperature.

Since the temperature is constant, we can simplify the equation to P1V1 = P2V2. We know that the initial pressure (P1) is 5.06 atm and the initial volume (V1) is 8.52 L.

We want to find the final pressure (P2) when the volume (V2) is 10.90 L. Plugging these values into the equation, we get (5.06 atm)(8.52 L) = P2(10.90 L). Solving for P2, we get P2 = (5.06 atm)(8.52 L) / (10.90 L) = 3.94 atm.

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Carbon dioxide gas will be more soluble in 100g of water at 25°C when the pressure is higher.

To answer this question, we need to consider how pressure affects the solubility of carbon dioxide gas in water at a given temperature (25°C in this case). According to Henry's Law, the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid.

So, at a higher pressure, carbon dioxide gas will be more soluble in 100g of water at 25°C. Specifically, as the pressure of carbon dioxide above the water increases, more CO₂ molecules will dissolve in the water, resulting in increased solubility.

In summary, carbon dioxide gas will be more soluble in 100g of water at 25°C when the pressure is higher.

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Answer:

Answer: The final volume of the gas will be 8.07 L.

Approximate number of tubes Amelia can fill = 8.07 L/500 mL = 16.14 tubes.

The sequences of DNA are used in transcription and translation to determine the structure and functions of proteins in hydrophobic environments through a complex process that involves multiple steps.

Transcription: Translation & Protein Folding and Function

Transcription

The first step in protein synthesis is transcription, where the DNA sequence is copied into a single-stranded RNA molecule. The RNA molecule carries the genetic information from the DNA to the ribosome, where it is translated into a protein.

During transcription, the DNA is unwound and one of the DNA strands serves as a template for RNA synthesis.

The RNA molecule is synthesized in a 5' to 3' direction by RNA polymerase, using nucleotides that are complementary to the DNA template.

The sequence of nucleotides in the RNA molecule is determined by the sequence of nucleotides in the DNA template. The RNA molecule is then processed by splicing, capping, and polyadenylation to form the mature mRNA molecule.

Translation:

In the second step of protein synthesis, translation, the genetic information carried by the mRNA molecule is used to synthesize a protein. The ribosome reads the mRNA molecule in codons, which are groups of three nucleotides that code for specific amino acids.

The ribosome then matches each codon with a complementary tRNA molecule, which carries the corresponding amino acid. The amino acids are joined together by peptide bonds to form a polypeptide chain.

The sequence of amino acids in the polypeptide chain is determined by the sequence of codons in the mRNA molecule.

Protein Folding and Function:

Once the polypeptide chain is synthesized, it folds into a specific three-dimensional shape, which is determined by the sequence of amino acids in the chain. The hydrophobic and hydrophilic properties of the amino acids in the chain determine how the protein will fold and how it will interact with its environment.

In hydrophobic environments, hydrophobic amino acids tend to be buried in the interior of the protein, while hydrophilic amino acids tend to be exposed on the surface of the protein. The three-dimensional structure of the protein determines its function.

Proteins can act as enzymes, receptors, transporters, or structural components, among other functions, depending on their three-dimensional structure.

In summary, the sequence of nucleotides in DNA is transcribed into RNA and then translated into a polypeptide chain. The sequence of amino acids in the polypeptide chain determines the three-dimensional structure of the protein, which in turn determines its function in hydrophobic environments.

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The grams of H₂ produced, if the chemical reaction produces 129 grams of  AlCl₃ are 2.92 grams. (Option b)

To determine the grams of H₂ produced, we need to use the balanced equation and the molar ratios between AlCl₃ and H₂.

From the balanced equation:

2 moles of AlCl₃ react with 3 moles of H₂

To find the moles of AlCl₃ produced:

129 grams AlCl₃ x (1 mole AlCl₃ / molar mass AlCl₃) = moles of AlCl₃

Now, using the molar ratios, we can determine the moles of H₂ produced:

moles of AlCl₃ x (3 moles H₂ / 2 moles AlCl₃) = moles of H₂

Finally, we can convert the moles of H₂ back to grams:

moles of H₂ x (molar mass H₂ / 1 mole H₂) = grams of H₂

Let's calculate it:

Given:

Mass of AlCl₃ produced = 129 grams

Molar mass of AlCl₃:

Al: 26.98 g/mol

Cl: 35.45 g/mol x 3 = 106.35 g/mol

Total molar mass = 26.98 g/mol + 106.35 g/mol = 133.33 g/mol

Calculations:

moles of AlCl₃ = 129 g AlCl₃ / 133.33 g/mol = 0.9676 moles AlCl₃

moles of H₂ = 0.9676 moles AlCl₃ x (3 moles H₂ / 2 moles AlCl₃) = 1.4514 moles H₂

grams of H₂ = 1.4514 moles H₂ x (2.02 g/mol / 1 mole H₂) = 2.93 grams of H₂

Therefore, the correct answer is b. 2.92 grams.

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At a pH of 10.7 the cyclohexyl amine is neutral

The pka of a substances describes how strong an acid is and the rate of disociation or ability of a substance to form ions

The changes in the sounroding pH can make the substances to be neutral, protonated or deprotonated.

Based on this, if the pka of cyclohexyl amine is 10.7 and the pH is also 10.7 the substance is neutral.

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After 17.8 seconds, 525.71 grams of N₂O₅ will remain, given a first-order rate law and a half-life of 3.00 seconds.

To find the remaining grams of N₂O₅, we'll use the first-order rate law equation: Nt = N0 * (1/2)^(t / t1/2), where Nt is the amount remaining after time t, N0 is the initial amount, t is the time elapsed, and t1/2 is the half-life.

Given the initial amount of 1.00x10^4 grams and a half-life of 3.00 seconds, the equation becomes: Nt = 1.00x10^4 * (1/2)^(17.8 / 3.00).

Solving for Nt, we get Nt = 1.00x10^4 * (1/2)^5.933, which equals 525.71 grams of N₂O₅ remaining after 17.8 seconds.

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Answer:

Careless work

Explanation:

I think so

Answer:

8.1293534120006496

Explanation:

hope this helps

To find the mass percent composition of an element, divide the mass contribution of the element by the total mass then multiply by 100.

The total mass = 200.0 g

Phosphorus mass = 87.28 g

Oxygen mass = 112.72 g

%composition of P:

=> (87.28 g/200.0g)*100

=> 43.64 %

%composition of O:

=> (112.72g/200.0 g)*100

=> 56.36 %

Answer:1.59

Explanation: For every mol of Ca(OH)2 there are two moles of OH so the concentration of OH is .013 x2 =.026 M OH

pOH = - log [OH] so -log .026 = 1.59

pOH is the negative logarithm of hydroxide ion concentration. 1.59 is the pOH of a 0.013 M Ca(OH)₂ solution.

The term pOH is defined as the negative of the logarithm of the OH− ion concentration. It is represented by the formula  pOH = - log [OH−].

pOH is the activity of acidity or alkalinity of a solution by determining the concentration of OH− ions.

If the pOH value is less than 7, the solution is basic. If the pOH value is equal to 7, the solution is neutral. If the pOH value is more than 7, the solution is acidic.

For every mol of Ca(OH)₂ there are two moles of hydroxide therefore, the concentration of OH is 0.013 x 2 = 0.026 M OH

According to the formula of pOH

pOH = - log [OH]

-log .026 = 1.59

Thus, the pOH of a 0.013 M Ca(OH)₂ solution is 1.59.

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Answer:

1. F) 2. F) 3. T) 4. T) 5. F) 6. F) 7. T) 8.F) 9.T) 10. T)

Explanation:

Not available.

The final structure should look like a slightly twisted boat conformation, with the ethyl group pointing down and the methyl group pointing out to the side. This is the lowest energy conformation of cis-1-ethyl-3-methylcyclohexane.

To draw cis-1-ethyl-3-methylcyclohexane in its lowest energy conformation, we first need to identify the cis isomer. This means that the ethyl and methyl groups are on the same side of the ring.

Next, we need to arrange the substituents on the cyclohexane ring in a way that minimizes steric hindrance. We can achieve this by placing the ethyl group in an axial position and the methyl group in an equatorial position.

To visualize this, draw a cyclohexane ring with one carbon atom labeled as the reference carbon. The ethyl group will be attached to the carbon atom in the axial position, which means that it will be pointing up or down. The methyl group will be attached to a carbon atom in the equatorial position, which means that it will be pointing out to the side.

To draw cis-1-ethyl-3-methylcyclohexane in its lowest energy conformation, start with a cyclohexane ring in a chair conformation. Next, place the ethyl group (C2H5) on carbon 1 and the methyl group (CH3) on carbon 3. Ensure both groups are on the same side of the ring (cis configuration). For lowest energy, place the ethyl group in an equatorial position and the methyl group in an axial position. This arrangement minimizes steric hindrance, thus providing the lowest energy conformation for cis-1-ethyl-3-methylcyclohexane.

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The number of molecules in 10.0 gram of NaOH is 15 * 10²².

To solve this question, we need to understand some terms of mole concept,

Mole - It is the amount of substance containing same number of molecules or atoms as there are atoms in 12 gram of carbon-12 isotope.

Molecules - It is group of atoms bonded together, representing the smallest fundamental unit of a chemical compound taking part in chemical reaction.

Molecular weight - The sum of atomic masses of all atoms in molecules.

Avogadro number - It is the number of atoms, ions, electrons, molecules in one mole of substance. It is represented as NA.

NA = 6.0 * 10²³ (approx)

To calculate the number of molecules, we apply the formulae,

no. of molecules = moles * NA

moles = weight / molecular weight

moles = 10.0 / 40

          = 0.25

Substituting this value to calculate number of molecules,

no. of molecules = 0.25 * 6.0 * 10²³

                            = 15 * 10²²

Therefore the number of molecules of in 10.0 g of NaOH is 15 * 10²².

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Answer:

''hydroxide ions make sodium hydroxide solution alkaline'' is true.

Explanation:

In the first sentence, OH+ ions is incorrect. It has to be OH- ions.

In the last sentence, hydride ions(H-ions) is incorrect. It has to be hydrogen ions(H+ ions).

Given data:H2O vapor content: 13 gramsH2O vapor capacity: 52 grams at 25 degrees Celsius 13 grams at 10∘C52 grams at 30∘CFormula used to find the dew point:$$\dfrac{13}{52}=\dfrac{(A*3\pi)/(ln100)}{(17.27-A)}$$$$\frac{1}{4}=\dfrac{(A*3\pi)/(ln100)}{(17.27-A)}$$

Where A is the constantDew Point:It is the temperature at which air becomes saturated with water vapor when the temperature drops to a point where dew, frost or ice forms. To solve this question, substitute the given data into the formula.$$13/52=\dfrac{(A*3\pi)/(ln100)}{(17.27-A)}$$$$13(17.27-A)=3\pi A(ln100)$$By simplifying the above expression, we get$$A^2-17.27A+64.78=0$$Using the quadratic formula, we get$$A=9.9,7.4$$

The dew point is 7.4 since it is less than 10°C.More than 100:The term "More than 100" has not been used in the question provided.

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Answer:

Q = 5805 Joules.

Explanation:

Given the following data;

Mass = 2250g

Specific heat capacity of silver = 0.129 J/g·°C

Initial temperature, T1 = 0.0°C

Final temperature, T2 = 200.0°C

To find the quantity of heat needed;

Heat capacity is given by the formula;

\( Q = mcdt\)

Where;

dt = T2 - T1

dt = 200 - 0

dt = 200°C

Substituting the values into the equation, we have;

\( Q = 225*0.129*200\)

Q = 5805 Joules.

Therefore, the amount of heat needed is 5805 Joules.

Given values:

                                                      \(= 200-0\)

                                                      \(= 200^{\circ} C\)

As we know the formula,

→ Heat capacity, \(Q = mcdt\)

By substituting the values, we get

                                \(= 225\times 0.129\times 200\)

                                \(= 5805 \ Joule s\)

Thus the above answer is right.

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