CHEMISTRY HIGH SCHOOL

Which aqueous solution has the lowest boiling point? A.0.20 m (NH4)2S
B. 0.20 m FeI3
C. 0.20 m K2SO4
D. 0.20 m C2H5OH

Answers

Answer 1
Answer:

Answer:- D. 0.20 m C_2H_5OH

Explanations:- When a on volatile solute is added to a solvent then the boiling point of the solution increases(elevated) and we call it elevation in boiling point.

Elevation in boiling point is directly proportional to the molality of the solution and the Van't Hoff factor "i" which is the number of ions we get on dissociation.

The equation is written as:

\Delta T_b=imk_b

where k_b is the boiling point elevation constant.

We have all the aqueous solutions, so the boiling point elevation constant value will remain same for all of them. The molality for all the solutions is also same. So, elevation in boiling point will depend only on the value of Van't Hoff factor.

Lower is the value of "i", lower will be the boiling point and vice versa.

The question asks, which aqueous solution has the lowest boiling point. So, we nede to choose the one with the lowest value of "i".

(NH_4)_2S(aq)\rightarrow 2NH_4^+(aq)+S^2^-(aq)

i = 3

FeCl_3(aq)\rightarrow Fe^3^+(aq)+3I^-(aq)

i = 4

K_2SO_4(aq)\rightarrow 2K^+(aq)+SO_4^2^-(aq)

i = 3

C_2H_5OH is a covalent molecule and so it does not dissociate to give the ions and hence the value of "i" for this is 1.

Comparing the "i" values for all the solutions, the least value is for ethyl alcohol means the boiling point of 0.20 m ethyl alcohol solution will be lowest.

So, the correct answer is D. 0.20 m C_2H_5OH .

Related Questions

Propane and oxygen react according to the equation: C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(g).How many grams of water can be produced from the complete combustion of 2.0 moles of C₃H₈(g)? a. 144.0 b. 82.0 c. 8.0 d. 44.8 e. 22.4
Which law states that the volume and absolute temperature of a fixed quantity of gas are directly proportional under constant pressure conditions?
Which of the following statements about subatomic particles best characterizes electrons? A positive charge, light, circling the nucleusB no charge, heavy, found in nucleusC negative charge, light, circling the nucleus D negative charge, heavy, circling the nucleus
How many grams of carbon dioxide (CO2) are found in a 11.9 L container under 1.5 atm and 20.0oC.
The chemical formula for aluminum hydroxide? is Al(OH)3. Which of the following is true about aluminum hydroxide?

Which event is endothermic? the burning of a match the change of water vapor to a liquid the combustion of propane gas the melting of ice?

Answers

The melting of ice is an event which is endothermic. Endothermic is the process when heat is transfer from the environment to the object. It happens when the onject absorbs the heat just like melting of ice. The ice is in solid form due to the compaction of positively charged atoms in it but when heat carrying electrons made contact to it, it melted.

Answer:

D. The melting of ice

Explanation:

An endothermic reaction ABSORBS heat from its surroundings, it does NOT give heat off into its surroundings.

so...

When a match burns, it gives of heat. So A is incorrect.

When water goes from a vapor into a liquid, the water molecules loose kinetic energy, they do not gain it. And since temperature is the measure of the average kinetic energy in a substance, the water vapor looses heat. If the process was endothermic, it would be gaining heat. So B is incorrect.

When propane gas combusts, the explosion lets off heat into its surroundings, it does not absorb heat. So C is incorrect.

Here's what happens when something melts: the molecules inside the substance receive more and more kinetic energy, until the substance's molecules have enough kinetic energy to vibrate and wiggle past each other, breaking their structure. When ice melts it is receiving kinetic energy from its surroundings, and again, since temperature is the measure of the average kinetic energy in a substance, the process is absorbing heat. Q.E.D.,

D is the correct answer.

What SI unit would best be used to express the height of your classroom ceiling ?

Answers

Since height is a basic physical property of length, the height of a classroom ceiling is expressed in meters, or meters, or meters.

What is physical property of length?

There are some physical characteristics of matter, such as length, mass, volume, weight, and so forth, that are dependent on the amount or size of the substance.

As the size or amount of the matter changes, so do these qualities of matter and their values.

A quality of matter that is unrelated to a change in its chemical makeup is called a physical property.

Density, color, hardness, melting and boiling points, and electrical conductivity are a few common examples of physical qualities.

The physical characteristics include color, phase, odor, and boiling point. Reactivity with oxygen is not a physical quality because it depends on the chemical makeup of the thing.

Therefore, meter is used to express the height of your classroom ceiling.

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Feet would be the best unit to use. Yards would work as well though. 
Hope that helps!

The solution set of axequalsb is the set of all vectors of the form wequalspplusbold v subscript h​, where bold v subscript h is any solution of the equation axequals0.

Answers

Answer : Incorrect

Explanation : In the given solution set of Ax = b;
is set of all vectors to form w= p + V_(h)
here V_(h) is is any solution of the equation Ax = 0;

this stands to be incorrect, as the correct would only exists when some vector p is found to be like this Ap=b

One of the first labs to analyze oxygen consumption was

Answers

Answer:

One of the first labs to analyze oxygen consumption was established by Lavoisier and Laplace in the late 18th century.

Explanation:

Final answer:

Initial laboratories studying oxygen consumption used innovative techniques, such as isotope tracers, and advanced equipment, such as respirometers, to examine various organisms and processes. Renowned scientist Mildred Cohn played a crucial role in this early research, providing insights into metabolic pathways and enzyme mechanisms.

Explanation:

The first labs to investigate oxygen consumption studied a variety of concepts and organisms. Pioneering this study, Mildred Cohn made significant discoveries utilizing isotopes as tracers in reactions. This strategy provided invaluable insights into metabolic pathways and enzyme mechanisms. Specifically, this strategy was used to understand the phosphorylation of glucose in mitochondria.

The respirometer is an essential tool in measuring oxygen consumption. In an experiment conducted in a laboratory, mice were used to observe the respiration levels at different temperatures. This was done by tracking the volume of oxygen each mouse consumed over multiple five-minute trials.

Also, oxygen consumption in humans can be combined with our understanding of our digestive process. The energy humans and other organisms need to function normally is generated through the gradual oxidation of chemical compounds in the body. Oxygen acts as the ultimate oxidizing agent in these reactions, linking to our digestion and energy conversion processes.

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Ca(OH)2 is added to a large beaker of water. How is the solution different from the original water?A...The solution turns blue litmus to red.

B...The solution turns phenolphthalein pink.

C...The solution has more hydrogen ions.

D....The solution has fewer hydroxide ions.

Answers

When Ca(OH)₂ is added to a beaker of water the solution would turn phenolphthalein pink.  Phenolphthalein is a common indicator and is only pink when in basic solutions.  By adding calcium hydroxide, you are turning the solution into a basic solution since the concentration of OH⁻ ions is going up and therefore any phenolphthalein in solution would turn pink.
(answers A,C, and D would happen if you added an acid to the water such as HCl)
I hope this helps.  Let me know if anything is unclear.

Ca(OH)2 is added to a large beaker of water. The solution different from the original water are the solution turns blue litmus to red, will has more hydrogen, and has fewer hydroxide ions.

What is a solution?

A solution is a mixture of two or more solute into solvents. Solution is made by mixing of two or more molecules.

For example, is a solution of water and salt.

Thus, the correct option is A, C, and D.

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What is the percent composition of calcium (Ca) in CaO?A 56g/40g x 100%
B 16g/56g x 100%
C 40g/56g x 100%
D 40g/100% x 56g

Answers

Answer:

C 40 g/56 g × 100 %

Explanation:

Calculate the mass of each component and the total mass.

Element  Atomic mass/u  No. of atoms  Subtotal mass/u

     Ca              40.08                     1                     40.08

     O                16.00                      1                    16.00

                                                               Total = 56.08

The formula for mass percent is

% by mass = Mass of component/Total mass × 100 %

In this problem

% Ca = mass of Ca/mass of CaO × 100 %

% H = 40.08 g/56.08 g × 100 %

The percentage composition of calcium (Ca) in CaO is option C.

  • Here we have to determine the mass of every component and even the total mass.

Element  Atomic mass/u  No. of atoms  Subtotal mass/u  

    Ca              40.08                     1                     40.08  

    O                16.00                      1                    16.00  

                                                              Total = 56.08

  • The mass percent formula is

\%\ by\ mass = Mass\ of\ component / Total\ mass * 100 \%  

 \% Ca = mass\ of\ Ca/ mass\ of\ CaO * 100 \%\n\n\% H = 40.08 g/ 56.08 g * 100 \%

Therefore, we can conclude that the correct option is C.

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