A student dissolves 15.0 g of ammonium chloride(NH4Cl) in 250. 0 g of water in a well-insulated open cup. She then observes the temperature of the water fall from 20.0 oC to 16.0 oC over the course of minutes. Use this data, and any information you need from the ALEKS Data resource, to answer the questions below about this reaction:
NH4Cl(s) rightarrow NH4+(aq) + Cl-(aq)
You can make any reasonable assumptions about the physical properties of the solution. Note for advanced students: it's possible the student did not do the experiment carefully, and the values you calculate may not be the same as the known and published values for this reaction.
1. Is this reaction exothermic, endothermic, or neither?
2. If you said the reaction was exothermic or endothermic, calculate the amount of heat that was released or absorbed by the reaction in this case.
3. Calculate the reaction enthalpy deltaHrxn per mole of NH4CI.

Answers

Answer 1

Answer:  

1) Endothermic.  

2) [tex]Q_{rxn}=4435.04J[/tex]  

3) [tex]\Delta _rH=15.8kJ/mol[/tex]

Explanation:  

Hello there!  

1) In this case, for these calorimetry problems, we can realize that since the temperature decreases the reaction is endothermic because it is absorbing heat from the solution, that is why the temperature goes from 22.00 °C to 16.0°C.  

2) Now, for the total heat released by the reaction, we first need to assume that all of it is released by the solution since it is possible to assume that the calorimeter is perfectly isolated. In such a way, it is also valid to assume that the specific heat of the solution is 4.184 J/(g°C) as it is mostly water, therefore, the heat released by the reaction is:

[tex]Q_{rxn}=-(15.0g+250.0g)*4.184\frac{J}{g\°C}(16.0-20.0)\°C\\\\ Q_{rxn}=4435.04J[/tex]    

3) Finally, since the enthalpy of reaction is calculated by dividing the heat released by the reaction over the moles of the solute, in this case NH4Cl, we proceed as follows:

[tex]\Delta _rH=\frac{ Q_{rxn}}{n}\\\\\Delta _rH= \frac{ 4435.04J}{15.0g*\frac{1mol}{53.49g} } *\frac{1kJ}{1000J} \\\\\Delta _rH=15.8kJ/mol[/tex]

Best regards!  

Best regards!


Related Questions

When P4O10(s) reacts with H2O(l) to form H3PO4(aq) , 453 kJ of energy are evolved for each mole of P4O10(s) that reacts. Write a balanced thermochemical equation for the reaction with an energy term in kJ as part of the equation.

Answers

Answer:

P4O10 + 6H2O → 4H3PO4         ΔH = 453 kJ

Explanation:

A thermochemical reaction is one in which the amount of heat gained/evolved is written as part of the reaction equation.

A thermochemical equation helps us to judge whether an equation is endothermic or exothermic. For an endothermic reaction, ΔH  is positive while for an exothermic reaction ΔH is negative.

Since, the reaction of one mole of P4O10(s)  with H2O(l) to form H3PO4(aq) evolves 453 kJ of energy for each mole of P4O10(s) that reacts. Then we can write;

P4O10 + 6H2O → 4H3PO4         ΔH = 453 kJ

It takes 45.60 mL of a 0.225 M hydrochloric acid solution to react completely with 25.00 mL of calcium hydroxide in this reaction below, what is the molar concentration of the calcium hydroxide solution?


2HCl(aq) + Ca(OH)2(aq)!CaCl2(aq) + 2H2O(l)

Answers

Given :

It takes 45.60 mL of a 0.225 M hydrochloric acid solution to react completely with 25.00 mL of calcium hydroxide in the given reaction.

2HCl(aq) + Ca(OH)2(aq) --> CaCl2(aq) + 2H2O(l)

To Find :

The molar concentration of the calcium hydroxide solution.

Solution :

From given equation 2 mole of hydrochloric acid react with 1 mole of calcium hydroxide.

So,

[tex]2M_1V_1 = M_2V_2\\\\2\times 0.225 \times 45.60 = M_2 \times 25 \\\\M_2 = \dfrac{20.52}{25}\\\\M_2 = 0.8208 \ M[/tex]

Therefore, molar concentration of the calcium hydroxide solution is 0.8208 M.

Answer:

Molar concentration of the calcium hydroxide solution = 0.2052 M

Explanation:

Volume of HCl = 45.60 mL  = 0.0456 L

Molar concentration of HCl = 0.225 M

Volume of Ca(OH)2 = 25.00 mL  = 0.025 L

No. of moles of HCl = (0.225 M)*(0.0456 L)   = 0.01026 mol

As we know

2 moles of HCl require 1 mole of Ca(OH)2, hence, .01026 moles of HCl will need 0.5*(0.01026) = 0.00513 moles of Ca(OH)2

Molar concentration of Ca(OH)2 = [(0.00513 mol)/(0.025 L)]   = 0.2052 M

determine the kinetic energy of a 1000-kg rollor coaster car that is moving with the speed of 20.0 m/s​

Answers

Given :

Mass of roller coaster, m = 1000 kg.

Speed with which roller coaster is moving, v = 20.0 m/s.

To Find :

The kinetic energy if roller coaster.

Solution :

We know, kinetic energy of any object of mass m and speed v is given by :

[tex]K.E = \dfrac{mv^2}{2}\\\\K.E = \dfrac{1000\times 20^2}{2}\ J\\\\K.E = 200000\ J\\\\K.E = 200\ kJ[/tex]

Therefore, the kinetic energy of roller coaster is 200 kJ.

How did the industrial Revolution impact the population of peppered moths in Britain?

The Industrial Revolution caused the proportions of each color morph in the population to become equal.

The light-colored moths became more common

The dark-colored moths became more common

The Industrial Revolution caused the proportions of each color morph in the population to become unequal

Answers

Answer:

due to the pollution the light months tended to stand out against the the wood that was dark due to the smoke the darker months population grew due to the fact that they were more harder to see for the predators

Answer:

The dark colored months became more common

Explanation:

Thats the answer !

The addition, removal, or substitution of nitrogenous bases in a DNA molecule may be caused by . Synapsis C. Disjunction B. Hybridization D. Mutation

Answers

Answer:

D. Mutation

Explanation:

Mutation is any change or alteration that occurs to the nucleotide sequence of a gene induced during DNA replication or by mutation-causing substances called MUTAGENS.

Mutation can be in the form of addition, removal, or substitution of nitrogenous bases in a DNA molecule. For example, in an original DNA sequence as follows: GAT ATC TGA, the following mutation can occur:

Addition: GAT ATC CTG A

Removal: GAT ATT GA

Substitution: GAT CTC TGA

What happened on March 15 in the year 44 B.C.? Caesar began a civil war. Caesar's enemies killed him. C. The Council of the Plebs met. d. All enslaved people were freed. Please select the best answer from the choices provided Com o C​

Answers

Answer:

Caesar's enemies killed him.

Explanation:

On March 15, 44 B.C.E., Julius Caesar was stabbed to death in Rome, Italy. . A group of as many as 60 conspirators decided to assassinate Caesar at the meeting of the Senate on March 15, the ides of March.

Hope this helped!!!

Caesars enemies killed him

A balloon at 30.0 C has a volume of 222 ml. if the temperature is increased to 62.1 C and the pressure remains constant, what will the new volume be, in mL?

Answers

30.0c has the volume of 222

The concept Charles's law is used here to determine the new volume. At the condition of constant pressure the new volume of the balloon is 459.54 mL.

What is Charles's law?

At constant pressure, the volume of a given mass of gas is directly proportional to the temperature on Kelvin scale. Mathematically, the law can be expressed as follows:

V = constant × Temperature

V / T = Constant

V = Volume

T = Temperature

The Charles's law also explained that at -273°C, the volume of all the gases will become zero. This temperature is defined as the absolute zero.

For two different gases with volumes V₁ and V₂ and temperatures T₁ and T₂ is represented as:

V₁ / T₁ = V₂ / T₂

V₂ = V₁T₂ / T₁

222 × 62.1 / 30.0 = 459.54 mL

Thus the new volume of balloon is 459.54 mL.

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What process is represented by this redox equation?
C6H12O6 + 602 -> 6H20 + 6CO2

A. Rusting
B. Photosynthesis
C. Cellular respiration
D. Combustion

Answers

The redox equation C6H12O6 + 6O2 -> 6H2O + 6CO2 represents the process of cellular respiration. Option C

Cellular respiration is a biochemical process that occurs in living organisms, including plants and animals, to convert organic compounds, such as glucose (C6H12O6), into usable energy in the form of adenosine triphosphate (ATP). It is the primary process by which cells derive energy to carry out their functions.

In the given equation, glucose (C6H12O6) is being oxidized, losing electrons, and releasing carbon dioxide (CO2) as a byproduct. This oxidation process results in the production of energy-rich molecules, such as ATP.

Additionally, oxygen (O2) is being reduced, accepting the electrons from glucose and combining with hydrogen (H) to form water (H2O). This reduction process allows for the transfer of electrons and the generation of energy.

The process of cellular respiration is essential for the survival and functioning of organisms, as it provides the necessary energy for various metabolic activities, growth, and maintenance of cellular processes.

It is a fundamental metabolic pathway found in both plants and animals, enabling them to extract energy from organic molecules through the oxidation of glucose or other fuel sources.

Therefore, option C, cellular respiration, is the correct answer that represents the process described by the given redox equation.

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Which of the following molecules are Polar? Select all that apply.
Group of answer choices
A.CH3Cl
B.HF
C.O2
D.PF5
E.HCN
F.SeBr6
G.H2S

Answers

The molecule that is polar is B C G

Potential and kinetic energy are similar in that -
COME ON BESTIES I NEED HELP​

Answers

Answer:

They refer to energy that moves. Kinetic energy is energy that is currently moving. Potential refers to energy that has yet to move, or simply energy in wait

Explanation:

Answer:

I'm not 100% but a possible answer could be: No energy could either be created or destroyed

LMK if not but good luck!

Titrations provide a method of quantitatively measuring the concentration of an unknown solution.

a. Trueb. False

Answers

Answer: True

Explanation:

Titration is a quantitative technique where a solution of known concentration is used to determine the concentration of an unknown solution. The titrant (the known solution) is added from a burette to a known quantity of the the unknown solution until the reaction is complete.

By knowing the volume of titrant,  we can determine the concentration of the unknown.

Thus the statement Titrations provide a method of quantitatively measuring the concentration of an unknown solution is True .

In order for a roller coaster to work, why does the hill the cart climbs need to be higher than the top of the loop?

Answers

Answer:

Explanation:

At the highest point of the first and tallest slope, your potential energy is at its most elevated it will at any point be on this ride. As you plunge, your potential energy diminishes until it's totally gone at the lower part of the slope." The more limited the slope the exciting ride climbs, the more prominent its active energy.

Another way of saying is that

A roller ride works utilizing gravity. the underlying slope must be sufficiently high that gravity can create sufficient force to finish the course.

Brainliest?

Please answer the following questions.
Which of the following is true? Select all that apply.
True
True
True
True
False User intent refers to what the user was trying to accomplish by
False A page can have a high Needs Met rating even if it is not related
False The meaning of a query may change over time.
False All queries belong to a locale.

Answers

The true statements are

User intent refers to what the user was trying to accomplish by using a search query.The meaning of a query may change over time.

The false statements are.

A page can have a high Needs Met rating even if it is not related to the user's search intent. All   queries do not necessarily belong toa specific locale.

 What is the explanation for this ?

The true statements reflect accurate concepts in relation to user intent and the dynamic nature of query meanings.

User intent refers to the purpose or goal the user has in mind when conducting a search.

Query meanings can evolve over time due to various factors such as changes in language usage,cultural shifts, or emerging   trends. The false statements, on the other hand,do not align with the actual understanding of these concepts.

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how many molecules of sodium chloride are in 2.5 moles??

Answers

Answer:

1.5x1024

Explanation:

2. What mass of NaOH is contained in 250.0 mL of a 0.400
M sodium hydroxide solution?

Answers

Answer:Explanation:

250.ml of a 0.400 divide


Which equation is an example of a redox reaction?

A. Ca(OH)2 + H2SO3 + 2H20 + CaSO3

B. HCI + KOH + KCI + H20

C. 2K+ CaBr +2KBr + Ca

D. BaCl2 + Na2SO4 + 2NaCl + BaSO4

Answers

Answer:

The answer is C.

Explanation:

A P E X approved :)

is copper II nitrate binary or ternary

Answers

Answer:

Ternary

Explanation:

A ternary ionic compound is an ionic compound composed of three or more elements. Copper II Nitrate is a ionic compound and contains 3 elements thus making it Ternary

What is the mass in grams of 3.40 x 10 24 atoms he

Answers

Answer:

Avogadro's constant says that  

1

mole of any atom contains  

6.022

10

23

atoms. In this case you have  

3.40

10

22

atoms:

3.40

10

22

atoms

6.022

10

23

atoms

mol

=  

5.65

10

2

m

o

l

Step 2

The atomic mass of helium (He) will give you the weight of one mole of this molecule:  

1

mol =  

4.00

gram:

4.00

g

mol

5.65

10

2

mol

=  

0.226

g

So the  

3.40

10

22

helium atoms weigh  

0.226

gram

.

Explanation:

Mark as brainlyiest

what is the mass of 3.2 moles of NaCl??

Answers

Answer:

116.88554 grams

Explanation:

*sweating profusely*

i had to look it up

Answer:

187.01686400000003 grams

Explanation:

Please help ASAP

Identify the atom with the ground-state electron configuration shown for its valence shell.
3s^2 3p^1

Answers

Aluminum. chemical element with symbol Al

Pls someone help me with this question pls

Answers

Answer:

D

Explanation:

It’s D I believe but I could be wrong

5 ways light changes objects

Answers

1) it can make the object glow, making it more seeable
2) it could make the object hot if the light stays on it for long enough
3) it forms energy, such as light helps makes plants grow
4) it can make it change colors, such as if you put a flashlight underneath a balloon making it a lighter colour
5) it can reflect of the objects, such as a mirror

What is the ratio by atoms of elements present in technetium (VII) peroxide? (peroxide
is a polyatomic ion)
1:7
2:8
4:9
3:1

Answers

Answer: 1:7

Explanation: 2 Tc^+7 + 7 O2^-2 -> Tc2 (O2)7

Also 2 Tc to 14 O

please help me out!! 10 points <3

Answers

Answer:it’s b

Explanation:I took. The test and got 100

Answer:

a- i know the other person said that it was b but i looked it but and it seems to be A. whoops-

Explanation:

A reaction vessel for synthesizing ammonia by reacting nitrogen and hydrogen is charged with 5.54 kg of H2 and excess N2. A total of 25.6 kg of NH3 are produced. What is the percent yield of the reaction?

Answers

Answer:

81.5

Explanation:

smartworks

what volume of 1.75 h2so4 would be needed to neutralize 350 ml of 3.33 m sodium hydroxide?​

Answers

Answer:

1.332 L

Explanation:

The reaction that takes place is:

H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O

First we calculate the number of NaOH moles, using the given volume and concentration:

350 mL * 3.33 M = 1165.5 mmol NaOH

Then we convert NaOH moles into H₂SO₄ moles, using the stoichiometric coefficients:

1165.5 mmol NaOH * [tex]\frac{2mmolH_2SO_4}{1mmolNaOH}[/tex] = 2331 mmol H₂SO₄

Finally we calculate the required volume of a 1.75 M solution of H₂SO₄, using the concentration and number of moles:

2331 mmol / 1.75 M = 1332 mL

We can convert mL into L:

1332 mL / 1000 = 1.332 L

Determine the amount of current going through a 50ohms; resistor with a voltage of 120 v

Answers

Answer:

98.356 ohms is the answer

Hydrogen chloride dissolved in water yields hydrochloric acid. What is the
molar concentration of HCl if 3.65 g of hydrogen chloride is dissolved in 500 mL of
water?

Answers

Answer:

1500ml

Explanation:

molarity=3.65⋅g36.5⋅g⋅mol−1500⋅mL×10−3⋅L⋅mL−1=0.200⋅mol⋅L−1

Consider a solution which is 0.10M in NH3 and 0.20M in NH4Cl. Choose ALL of the following that are false. If a small amount of NaOH is added, the pH becomes slightly more basic. If HCl is added, the H ions react with the NH3. If a small amount of HCl is added, the pH becomes slightly more basic. If NaOH is added, the OH- ions react with the NH3. If NH4NO3 is added, the pH becomes more basic.

Answers

Answer:

The incorrect or the false options are -

(B) - If NH4NO3 is added, the pH becomes more basic.

(D) - If a small amount of HCl is added, the pH becomes slightly more basic.

 (E) - If NaOH is added, the OH- ions react with the [tex]NH_3[/tex].

Explanation:

The given solution the buffer basic .

When a small amount of either is added, the hydrogen ion reacts with the ammonium ion, raising the pH slightly.When a small amount of HCl is added, the hydronium ion reacts with the ammonia, raising the pH slightly.

Therefore , the options A ( If a small amount of NaOH is added, the pH becomes slightly more basic.) and C ( If HCl is added, the H+ ions react with the NH3.) All other B , D , E are false .

A balloon has a pressure of 3.5atm and a volume of 4.2L. What will the volume of the balloon be if the pressure is increased to 7.0atm? Assume that temperature remains constant. SHOW ALL WORK FOR FULL CREDIT!​

Answers

2.1 L

P1V1 = P2V2

P1 = 3.5 atm
V1 = 4.2 L
P2 = 7.0 atm
V2 = ?

Solve for V2 —> V2 = P1V1/P2
V2 = (3.5 atm)(4.2 L) / (7.0 atm) = 2.1 L

The volume of the balloon is 2.1L.

What is volume?

Volume is the amount of space the matter occupies. The SI unit of volume is cubic meter.

Using Boyles law equation,

P1V1 = P2V2

Where P1 and V1 are the initial pressure and volume of the gas

           P2 and V2 are the final pressure and volume of the gas

Given:

P1 = 3.5atm

V1 = 4.2L

P2 = 7.0atm

V2 = ?

Solve for V2 ,

V2 = P1V1/P2

V2 = (3.5atm x 4.2 L) / (7.0atm)

     = 2.1L

Hence, the volume of the balloon is 2.1L.

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