What happened to the limewater in
the experiment? What does this
prove?

The given question is incomplete, the complete question is:

Calculate the free energy of formation of NaBr(s) given the following information: NaBr(s) → Na(s) + 1/2Br2(l), ΔG° = 349 kJ/mol

A) –309 kJ/mol

B) –329 kJ/mol

C) None of the above

D) –349 kJ/mol

E) –369 kJ/mol

Answer:

The correct answer is option D, that is, -349 kJ/mol.

Explanation:

Based on the given information, the reaction is:  

NaBr (s) ⇔ Na (s) + 1/2 Br₂ (l), the ΔG° of the reaction given is 349 kJ per mole. In the given question, it is clearly mentioned that there is a need to determine the free energy of the formation of NaBr. Thus, there is a need to keep Na (s) and Br₂ (l) at the reactant side and NaBr (s) at the product side.  

Therefore, there is a need to reverse the reaction and change the sign on ΔG.  

Now the reaction will become,  

Na (s) + 1/2 Br₂ (l) ⇔ NaBr (s), and the ΔG° will now become -349 kJ per mole. Hence, -349 kJ per mole is the free energy of the formation of NaBr (s).  

Answer:

Samarium:

Electron configuration:

Samarium

Explanation:

Samarium is a chemical element that belongs to the lanthanoid series. The lanthanoids are the chemical elements that follow lanthanum. They are all known to possess 4f orbitals. The 4f electrons are found in the antepenultimate shell of the elements of the lanthanoid series and they do not take part in chemical bonding. They are neither removed in bonding nor do they take part in crystal field stabilization of lanthanoid complexes.

The electronic configuration of samarium is; 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f6 while the condensed, short hand electronic configuration is [Xe] 4f6 6s2. This corresponds to (noble gas]ns2(n − 2) f6 as required by the question, hence the answer provided above.

Answer: The answer is true

Answer:

Explanation:

The energy of a photon emitted when the electron moves from the 3rd orbital to the 2nd orbital is exactly same as the energy of a photon absorbed when the electron moves from the 2nd orbital to the 3rd orbital

Answer: A

Explanation:

Answer:

a. both temperature changes will be the same

Explanation:

When sodium hydroxide (NaOH) is dissolved in water, a determined amount is released to the solution following the equation:

Q = m×C×ΔT

Where Q is the heat released, m is the mass of the solution, C is the specific heat and ΔH is change in temperature.

Specific heat of both solutions is the same (Because the solutions are in fact the same). Specific heat = C.

m is mass of solutions: 102g for experiment 1 and 204g for experiment 2.

And Q is the heat released: If 2g release X heat, 4g release 2X.

Thus, ΔT in the experiments is:

Experiment 1:

X / 102C = ΔT

Experiment 2:

2X / 204C = ΔT

X / 102C = ΔT

That means,

Answer:

Fronts

Explanation:

For example, there are hot and cold fronts which cause the air to become warmer or cooler in a specific region!

Hope this helps! Please mark as brainiest!

Answer:

[tex]M=0.822M[/tex]

Explanation:

Hello,

In this case, given the mathematical definition of molar concentration as the moles of solute divided by the liters of solution:

[tex]M=\frac{n}{V}[/tex]

We can easily compute it by firstly computing the moles of sugar by using its molar mass:

[tex]n=73.1g*\frac{1mol}{342.30g} =0.214mol[/tex]

After that, we compute the concentration by realizing 259.8 mL equals 0.2598 L:

[tex]M=\frac{0.214mol}{0.2598L}\\ \\M=0.822mol/L[/tex]

Or just:

[tex]M=0.822M[/tex]

Considering molar units as mol/L

Best regards.

The molar concentration of the solution is 0.82 M

We'll begin by by converting 259.8 mL to L. This can be obtained as follow:

1000 mL = 1 L

Therefore,

259.8 mL = 259.8 / 1000

Thus, 259.8 mL is equivalent to 0.2598 L.

Next, we shall determine the number of mole of the sugar. This can be obtained as follow:

Molar mass of sugar = 342.30 g/mol.

Mass of sugar = 73.1 g

Mole = mass / molar

Mole = 73.1 / 342.30

Finally, we shall determine the molar concentration of the sugar. This can be obtained as follow:

Mole of sugar = 0.214 mole

Volume = 0.2598 L

Molarity = 0.214 / 0.2598

Therefore, the molar concentration of the solution is 0.82 M

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Answer:

2.1 atm

Explanation:

Before we get the total pressure, we have to ensure all the gases have the same pressure unit.

Nitrogen gas = 0.75 atm

Helium = 490mmHg

To convert mmHg to atm;

760 mmHg = 1 atm

490 = x

x = 460 / 760 = 0.645 atm

Neon = 520 torr

Converting torr to atm;

760 torr = 1 atm

520 torr = x

x = 520 / 760 = 0.684 atm

The total pressure is then given as;

0.75 + 0.684 + 0.645 = 2.1 atm

Answer:

∆H > 0

∆Srxn <0

∆G >0

∆Suniverse <0

Explanation:

We are informed that the reaction is endothermic. An endothermic reaction is one in which energy is absorbed hence ∆H is positive at all temperatures.

Similarly, absorption of energy leads to a decrease in entropy of the reaction system. Hence the change in entropy of the reaction ∆Sreaction is negative at all temperatures.

The change in free energy for the reaction is positive at all temperatures since ∆S reaction is negative then from ∆G= ∆H - T∆S, we see that given the positive value of ∆H, ∆G must always return a positive value at all temperatures.

Since entropy of the surrounding= - ∆H/T, given that ∆H is positive, ∆S surrounding will be negative at all temperatures. This is so because an endothermic reaction causes the surrounding to cool down.

Answer:

3.07 × 10⁻⁴

Explanation:

Step 1: Calculate the concentration of H⁺

We will use the definition of pH.

[tex]pH = -log [H^{+} ]\\\[ [H^{+} ] = antilog -pH = antilog -2.37 = 4.27 \times 10^{-3} M[/tex]

Step 2: Calculate the concentration of HY

5.22 × 10⁻³ mol of HY are dissolved in 0.088 L. The concentration of the acid (Ca) is:

[tex]Ca = \frac{5.22 \times 10^{-3} mol }{0.088L} = 0.0593M[/tex]

Step 3: Calculate the acid dissociation constant (Ka)

We will use the following expression.

[tex]Ka = \frac{[H^{+}]^{2} }{Ca} = \frac{(4.27 \times 10^{-3} )^{2} }{0.0593} = 3.07 \times 10^{-4}[/tex]

Answer:

C. hydration number

Explanation:

When we dissolve an ionic compound (a charged species) the charges can interact with the water molecule. In the case of cations (positive charges) the negative dipole of water (generated in the oxygen) will interact with the positive charge at the same time the anions (negative charges) the positive dipole of water (generated in the hydrogen).

The amount of water molecules that can interact with a single ion (cation or anion) is called hydration number. In the example, we have a hydration number of "4" for the sodium cation.

I hope it helps!

Humans impact the physical environment in many ways: overpopulation, pollution, burning fossil fuels, and deforestation.

The  study of how humans impact the environment is known as "environmental science," and it describes both the positive and negative effects of humans on the climate.

Environmental science is the study of the environment, and it explains how the environment changes through such factors as human interaction, the biotic and abiotic parts of the environment, the temperature, humidity, etc. This branch of science explains the different interactions of humans and their adverse effects, such as pollution caused by human interference, global warming, climate change, etc.

Hence, the study of how humans impact the environment is known as "environmental science," and it describes both the positive and negative effects of humans on the climate.

Learn more about environmental science here.

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#SPJ2

Answer:

option 3

Explanation:

just took the test

Answer:

Streak is tested by scraping a mineral across a streak plate.

Explanation:

Answer:

The value of 2x+3y is 26

Explanation:

Because NH pattern gave hybridization Sp3

Just like NH3 Or NH2-

And SF pattern gave hybridization Sp3d2

Also just like SF6

X is the static no. of NH pattern

So X=4

Y is the static no. Of SF pattern

So Y = 6

Value of 2X+3Y

2*4 + 3*6

26

Answer:

The unknown element is Sb

Explanation:

The first thing we must note is that the unknown element must be a member of group 15 in the periodic table. This is clear from the fact that the two oxides formed are X2O3 and X2O5. This implies that the unknown element X must have a valency of 3 or 5. This corresponds to our knowledge that the outermost electron configuration of group 15 elements is ns2np3. Hence, group fifteen elements can have a valency of 3 or 5.

The electronic configuration of antimony is; [Kr]4d10 5s2 5p3. This implies that the atom is paramagnetic since there are three unpaired 5p electrons. The oxides of antimony are known to be amphoteric. An ampohoteric oxide reacts with both acid and base, hence the answer.

Answer:

i guess oil never dissolve in water. As like dissolve like. water is polar so it dissolves only polar substances

Explanation:

Answer:

None

Explanation:

Answer on Edge 2022

Answer:

The correct answer would be - 2.4KJ or, 2400J

Explanation:

Given:

heat capacity of liquid water - 4.18 J/g·°C

heat of vaporization - 40.7 kJ/mol

Mass of water = 1g

Moles of water = mass/molar mass

= 1g/18.016g

= 0.055 moles

Then,

Total heat required = q1(to raise the temperature to 100) + q2(change from the liquid phase to gas/steam)

= m *s*dt + moles * heat of vaporization

= (1g * 4.18 j/gc * (100-67)) + 0.055* 40.7 KJ

= 137.94J + 2.26KJ

=0.138KJ + 2.26KJ

=2.4KJ or, 2400J

Thus, the correct answer would be - 2.4KJ or, 2400J

Answer:

The constant Kc is expressed as:

[tex]Kc=\frac{[H_{2}CO_{3} ] }{[CO_{2}]*[H_{2}O] }[/tex] (option C)

Explanation:

A dynamic equilibrium is a reaction that is never completed, since it occurs simultaneously in both directions (the reactants form products, and in turn, these again form reactants).

When the concentrations of each one of the substances that intervene (reagents or products) stabilize, that is, they are spent at the same rate as they are formed, the Chemical Balance is reached.

For the study of chemical equilibrium it is useful to use a value called equilibrium constant. The equilibrium constant depends on the temperature.

For any reaction, represented by the generic chemical equation:

aA + bB ⇔ cC + dD

the constant Kc is expressed by:

[tex]Kc=\frac{[C]^{c} *[D]^{d} }{[A]^{a} *[B]^{b} }[/tex]

Then, the constant Kc is equal to the multiplication of the concentrations of the products raised to their stoichiometric coefficients by the multiplication of the concentrations of the reactants also raised to their stoichiometric coefficients.

So, in the case of:

CO₂ (aq) + H₂O (l) ⇄ H₂CO₃ (aq)

The constant Kc is expressed as:

[tex]Kc=\frac{[H_{2}CO_{3} ] }{[CO_{2}]*[H_{2}O] }[/tex] (option C)

Answer:

D. [HCHO₂] > [NaCHO₂]

Explanation:

Formic acid, HCHO₂, is a weak acid that, in presence of its conjugate base, NaCHO₂ (CHO₂⁻), produce a buffer following H-H equation:

pH = pKa + log [CHO₂⁻] / [HCHO₂]

As pKa of the acid is 3.74 and pH of the solution is 3.11:

3.11 = 3.74 + log [CHO₂⁻] / [HCHO₂]

-0.63 = log [CHO₂⁻] / [HCHO₂]

0.2344 = [CHO₂⁻] / [HCHO₂]

A ratio [CHO₂⁻] / [HCHO₂] < 1, means:

Answer:

1. 2+ ([tex]Cu^{2+}[/tex]).

2. 0 ([tex]Cu^0[/tex]).

Explanation:

Hello,

In this case, the described chemical reaction is a redox reaction in fact, since the oxidation states of both magnesium and copper change as shown due to the displacement:

[tex]Mg(s)+Cu(NO_3)_2(aq)\rightarrow Mg(NO_3)_2(aq)+Cu(s)[/tex]

Therefore:

1. Since copper is the cation in the copper (II) nitrate, the (II) means that its charge is 2+ ([tex]Cu^{2+}[/tex]).

2. Since copper is alone, it means no electrons are being neither shared not given, its charge is 0 ([tex]Cu^0[/tex]).

Best regards.

Answer:

Solid Wood

Explanation:

Wood is like a solid block, whereas gases flow freely and liquids spread to fill the shape of their container.

Please let me know if I misunderstood the question, by the way.

Answer: [tex]H_2(g)+I_2(g)\rightarrow 2HI(s)[/tex]

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

Thus in the reactants, there are 2 atoms of hydrogen and 2 atoms of iodine .Thus there has to be 2 atoms of hydrogen and 2 atoms of iodine in the product as well. Thus a coefficient of 2 is placed in front of HI.

The balanced chemical reaction is:

[tex]H_2(g)+I_2(g)\rightarrow 2HI(s)[/tex]

Answer:

A. 2Mg(s) + O2(g) —> 2MgO(s)

B. Mg is the limiting reactant.

C. Theoretical yield of MgO is 16.83g.

D. The percentage yield is 70.7%

Explanation:

A. The balanced equation for the reaction. This is given below:

2Mg(s) + O2(g) —> 2MgO(s)

B. Determination of the limiting reactant.

First, we shall determine the mass of Mg and O2 that reacted and the mass of MgO produced from the balanced equation. This is illustrated below:

Molar mass of Mg = 24g/mol

Mass of Mg from the balanced equation = 2 x 24 = 48g.

Molar mass of O2 = 16x2 = 32g/mol.

Mass of O2 from the balanced equation = 1 x 32 = 32g

Molar mass of MgO = 24 + 16 = 40g/mol

Mass of MgO from the balanced equation = 2 x 40 = 80g

Summary:

From the balanced equation above,

48g of Mg reacted with 32g of O2 to produce 80g of MgO.

Now, we can obtain the limiting reactant as follow:

From the balanced equation above,

48g of Mg reacted with 32g of O2.

Therefore, 10.1g of Mg will react with = (10.1 x 32)/48 = 6.73g of O2.

From the calculations made above, we can see that only 6.73g out of 10.5g of O2 given is needed to react completely with 10.1g of Mg.

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

C. Determination of the theoretical yield of MgO.

The limiting reactant is used in this case as it will produce the maximum yield of the reaction since all of I is used up in the reaction.

The theoretical yield can be obtain as illustrated below:

From the balanced equation above,

48g of Mg reacted to produce 80g of MgO.

Therefore, 10.1g of Mg will react to produce = (10.1 x 80)/48 = 16.83g of MgO.

Therefore, the theoretical yield of MgO is 16.83g.

D. Determination of the percentage yield.

This is illustrated below:

Actual yield of MgO = 11.9g

Theoretical yield of MgO = 16.83g

Percentage yield =..?

Percentage yield = Actual yield /Theoretical yield x 100

Percentage yield = 11.9/16.83 x 100

Percentage yield = 70.7%

Answer: pH=2.38

Explanation:

To calculate the pH, let's first write out the equation. Then, we will make an ICE chart. The I in ICE is initial quantity. In this case, it is the initial concentration. The C in ICE is change in each quantity. The E is equilibrium.

            HCOOH ⇄ H⁺ + HCOO⁻

I               1.0M          0          0

C              -x            +x        +x

E            1.0-x            x          x

For the steps below, refer to the ICE chart above.

1. Since we were given the initial of HCOOH, we can fill this into the chart.

2. Since we were not given the initial for H⁺ and HCOO⁻, we will put 0 in their place.

3. For the change, we need to add concentration to the products to make the reaction reach equilibrium. We would add on the products and subtract from the reactants to equalize the reaction. Since we don't know how much the change in, we can use variable x.

4. We were given the Kₐ of the solution. We know [tex]K_{a} =\frac{product}{reactant}=\frac{[H^+][HCOO^-]}{[HCOOH]}[/tex].

5. The problem states that the Kₐ=1.8×10⁻⁴. All we have to so is to plug it in and to solve for x.

[tex]1.8*10^-^4 =\frac{x^2}{0.1-x}[/tex]

6. Once we plug this into the quadratic equation, we get x=0.00415.

7. The equilibrium concentration of [H⁺]=0.00415. pH is -log(H⁺).

-log(0.00415)=2.38

Our pH for the weak acid solution is 2.38.

Answer:

fossil fuels are exhaustible, available in limited quantity, takes a long time to replenish & is found under the earth.

Since crude oil satisfies all these conditions, it is a fossil fuel.

Answer:

Based on the difference in solubility one can perform the process of purification of the benzoic acid contaminated with sodium chloride. The benzoic acid does not get soluble in cold water, while the sodium chloride is soluble in cold water.  

Thus, for separation, the supplementation of cold water can be done into the mixture in the experiment of purifying benzoic acid from sodium chloride. In the process, the mixture is placed on the ice bath and is stirred well, in the end, the solution is filtered. The filtrate contains sodium chloride and on the filter paper pure benzoic acid is collected.  

Answer:

Theoretical yield = 49.45g

Percentage yield= 93.6%

Answer:

[tex]Q=4154J[/tex]

Explanation:

Hello,

In this case, the involved heat in this heating process is considered to be computed via:

[tex]Q=nCp\Delta T[/tex]

Whereas we assume a constant molar specific heat of helium which is 20.77 J/(mol*K), thus, the transferred energy in the form of heat turns out:

[tex]Q=2mol*20.77\frac{J}{mol*K} *100K\\\\Q=4154J[/tex]

Regards.