An unknown substance has a melting point of -77°C. Is this substance likely to be an ionic compound?

The mass of 7.8 x 10^22 carbon atoms is 1.553 grams.

To determine the mass of 7.8 x 10^22 carbon atoms, we need to use the concept of molar mass and Avogadro's number.

The molar mass of carbon (C) is approximately 12.01 g/mol, which represents the mass of one mole of carbon atoms. Avogadro's number states that there are 6.022 x 10^23 atoms in one mole of any substance.

Now, let's calculate the mass of 7.8 x 10^22 carbon atoms:

Determine the number of moles:

Number of moles = Number of atoms / Avogadro's number

Number of moles = (7.8 x 10^22) / (6.022 x 10^23) = 0.1295 moles

Calculate the mass:

Mass = Number of moles x Molar mass

Mass = 0.1295 moles x 12.01 g/mol = 1.553 g

Therefore, the mass of 7.8 x 10^22 carbon atoms is approximately 1.553 grams.

The calculation is based on the understanding that the molar mass of carbon represents the mass of one mole of carbon atoms. By dividing the given number of atoms by Avogadro's number, we obtain the number of moles. Multiplying the number of moles by the molar mass gives us the mass in grams.

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Answer:

Because chemists need to think outside the box for what they do, in other words, "science is not always black and white" which means science has color to it or many different aspects some of those which are not yet discovered and needs critical thinking chemists to figure out and discover.

Explanation:

(this was all in my own words and not actually cut and Paiste ○|￣|_ =3)

1. 0.33 M

2. 0.278 M

Molarity is a way to express the concentration of the solution

Molarity shows the number of moles of solute in every 1 liter of solute or mmol in each ml of solution

\(\large{\boxed {\bold {M ~ = ~ \frac {n} {V}}}\)

Where

M = Molarity

n = Number of moles of solute

V = Volume of solution

1. 0.350 mol of NaOH in 1.05 L of solution.

n=0.35

V=1.05 L

Molarity :

\(\tt M=\dfrac{0.35}{1.05}=0.33\)

2. 14.3 g of NaCl in 879 mL of solution.

mol NaCl(MW=58.5 g/mol) :

\(\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{14.3~g}{58.5~g/mol}=0.244\)

Molarity :

\(\tt M=\dfrac{0.244}{0.879~L}\\\\M=0.278\)

Answer:

a) the final temperature of the air is 500° R

b) the amount of specific entropy produced is 0.0758 Btu/lb-°R  

Explanation:

Given the data in the question;

Air at 500° R = \(T_i\)

Using first law of thermodynamic;

δQ = dU + W

now, since the vessel is insulated, the transfer is zero, work done also is zero since there is also no external work done.

δQ = dU + W

0 = dU + 0

dU = 0

\(u_f\) - \(u_i\) = 0

\(u_f\) = \(u_i\)

hence, change in internal energy is 0

Now, since the ideal internal energy is a function of temperature, the temperature will also remain the same;

\(T_f = T_i\)

F = 500° R

Therefore, the final temperature of the air is 500° R

b)

given that; initial volume is one-third of the total volume

V₁ = \(\frac{1}{3}\)V₂

3V₁ = V₂

3 = V₂/V₁

Now, we take the value of gas constant R from air property table;  gas constant R = 0.069 Btu/lb-R  

so we calculate the entropy change;

Δs = \(c_v\)In( \(\frac{T_2}{T_1}\) ) + R.In( \(\frac{V_2}{V_1}\) )

we substitute

Δs = \(c_v\)In( \(\frac{500}{500}\) ) + 0.069 × In( 3 )

Δs = 0 + [0.069 × In( 3 )]

Δs = 0 + [0.069 × 1.0986]

Δs = 0.0758 Btu/lb-°R  

Therefore, the amount of specific entropy produced is 0.0758 Btu/lb-°R  

Insulated vessels separate the environment of the outer and the inner system. The final temperature is 500 degrees R and 0.0758 Btu/lb- degree R is the entropy.

The temperature is the measure of the hot or the coldness of the system.  The first law of the thermodynamics is used to measure the final temperature of the system:

\(\rm \Delta Q = \rm \Delta U + W\)

The work done will be zero as the system is insulated and no external work is being done.

\(\begin{aligned} \rm 0 &= \rm \Delta U + 0\\\\\rm U_{f} - U_{i} &= 0\\\\\rm U_{f} &= \rm U_{i} \end{aligned}\)

Hence, the change in the internal energy is zero. Thus, the final temperature will remain the same,

\(\rm T_{f} = \rm T_{i} = 500 ^{\circ} \rm R\)

Now, as we know, the initial volume is one-third of the total volume then,

\(\begin{aligned} \rm V_{1} &= \rm \dfrac{1}{3} V_{2}\\\\\rm 3V_{1}&= \rm V_{2}\\\\3 &= \rm \dfrac{V_{1}}{V_{2}}\end{aligned}\)

The change in entropy is calculated as:

\(\begin{aligned} \rm \Delta S &= \rm C_{v} ln ( \dfrac{T_{2}}{T_{1}}) + R \times ln ( \dfrac{V_{2}}{V_{1}}) \\\\&= 0 + [0.069 \times \rm ln( 3 )]\\\\& = 0.0758 \;\rm Btu/lb-^{\circ}R \end{aligned}\)

Therefore, the entropy produced is 0.0758 Btu/lb- degree R.

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Answer:

If it is elemental gas, the oxidation number is $$0$$.

Explanation:

The oxidation number of an atom in a chemical bond, is the charge left on the atom

The molarity of the NiSO₄ solution made by dissolving 38.81 grams of nickel (ii) sulfate, NiSO₄, in enough water to make 0.467 liters of solution is 0.535 M

First, we shall obtain the mole of 38.81 grams of nickel (ii) sulfate, NiSO₄. Details below:

Mole of NiSO₄ = mass / molar mass

= 38.81 / 154.75

= 0.25 mole

Now, we shall determine the molarity of the solution. Details below:

Molarity of solution = mole / volume

= 0.25 / 0.467

= 0.535 M

Thus, the molarity of the solution is 0.535 M

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Answer:

The cell potential for the given galvanic cell is 0.188 V.

Explanation:

To calculate the cell potential, we can use the Nernst equation:

Ecell = E°cell - (RT/nF)ln(Q)

where E°cell is the standard cell potential, R is the gas constant (8.314 J/mol·K), T is the temperature in Kelvin (25°C = 298 K), n is the number of moles of electrons transferred (in this case, n = 2), F is the Faraday constant (96,485 C/mol), and Q is the reaction quotient.

First, we need to write the half-reactions and their standard reduction potentials:

Sn4+(aq) + 2e- → Sn2+(aq) E°red = 0.15 V

Fe3+(aq) + e- → Fe2+(aq) E°red = 0.77 V

The overall reaction is the sum of the half-reactions:

Sn2+(aq) + 2Fe3+(aq) → Sn4+(aq) + 2Fe2+(aq)

The reaction quotient Q can be expressed as:

Q = [Sn4+][Fe2+]^2 / [Sn2+][Fe3+]^2

Substituting the given concentrations, we get:

Q = (0.00655)(0.01139)^2 / (0.0624)(0.0437)^2 = 0.209

Now we can calculate the cell potential:

Ecell = 0.15 V + 0.0592 V log([Fe2+]^2/[Fe3+]) + 0.0592 V log([Sn4+]/[Sn2+])

= 0.15 V + 0.0592 V log(0.01139^2/0.0437^2) + 0.0592 V log(0.00655/0.0624)

= 0.188 V

Therefore, the cell potential for the given galvanic cell is 0.188 V.

The cell potential for the given galvanic cell in which the given reaction occurs at 25 °C is 0.188 V.

To find the cell potential, we take the Nernst equation:

Ecell = E°cell - (RT/nF)ln(Q)

In which R is the gas constant (8.314 J/mol·K) and E° cell is the standard cell potential.

T temperature in Kelvin (25°C = 298 K), and n is the number of moles of electrons transferred (n = 2), Q is the reaction quotient and F is the Faraday constant (96,485 C/mol).

Firstly, write the half-reactions and then their standard reduction potentials:

Sn⁴⁺(aq) + 2e⁻  → Sn²⁺(aq) E°red = 0.15 V

Fe³⁺(aq) + e⁻ → Fe²⁺(aq) E°red = 0.77 V

The overall reaction is the sum of the half-reactions:

Sn²⁺(aq) + 2Fe³⁺(aq) → Sn⁴⁺(aq) + 2Fe²⁺(aq)

The Q reaction quotient can be written as:

Q = [Sn⁴⁺][Fe²⁺]² ÷ [Sn²⁺][Fe²⁺]²

Substituting the given concentrations, we observe:

Q = (0.00655)(0.01139)² ÷ (0.0624)(0.0437)² = 0.209

Next, we can find the cell potential:

Ecell = 0.15 V + 0.0592 V log([Fe²⁺]²/[Fe³⁺]) + 0.0592 V log([Sn⁴⁺]/[Sn²⁺])

= 0.15 V + 0.0592 V log(0.01139²÷0.0437²) + 0.0592 V log(0.00655÷0.0624)

= 0.188 V

Thus, the cell potential for the given galvanic cell is 0.188 V.

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Answer:

D Fracture

Explanation:

jus took the test

The mass of the cereal that you would need to consume can be obtained as 84.8 g

The number of moles, denoted by the symbol "n," is a fundamental unit of measurement in chemistry that represents the amount of a substance. It is used to quantify the quantity of atoms, molecules, or ions in a sample.

Number of moles of sucrose in the cereal = 11g/342 g/mol

= 0.03 moles

Now;

0.03 moles of sucrose is contained in 60 g of cereal

0.0424 moles of sucrose would contain 0.0424 moles * 60 g/0.03 moles

= 84.8 g

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Answer: 55.5 oC is 0.014 atm (3rd decimal point)

Explanation:

The Clausius-Clapeyron equation is given as:

ln(P2/P1) = -(ΔH_vap/R) * (1/T2 - 1/T1)

where:

P1 = vapor pressure at temperature T1

P2 = vapor pressure at temperature T2

ΔH_vap = enthalpy of vaporization

R = gas constant = 8.314 J/(mol*K)

Converting the enthalpy of vaporization to J/mol:

ΔH_vap = 35.2 kJ/mol = 35,200 J/mol

Converting temperatures to Kelvin:

T1 = 64.7 + 273.15 = 337.85 K

T2 = 55.5 + 273.15 = 328.65 K

Substituting the values into the equation and solving for P2:

ln(P2/1 atm) = -(35,200 J/mol / 8.314 J/(mol*K)) * (1/328.65 K - 1/337.85 K)

ln(P2/1 atm) = -4.231

P2/1 atm = e^(-4.231)

P2 = 0.014 atm

Therefore, the vapor pressure for methanol at 55.5 oC is 0.014 atm, to the third decimal point.

In order to test for ammonia, a moist red litmus paper should be held over the test tube containing the ammonia.  Option 3.

Ammonia is a substance that is alkaline in nature. All alkaline substances are able to turn red litmus paper to blue. This is in opposition to acidic substances that turn blue litmus paper to red.

Thus, the first test that can be used to determine if a substance is ammonia would be to hold a moist red litmus paper over the test tube containing the suspected substance.

Since ammonia is gas at room temperature, the substance suspected to be ammonia will diffuse from the test tube to turn the moist red litmus paper to blue.

Other methods to test for ammonia include passing a test tube containing hydrochloric acid over the test tube containing the substance. A white fume of ammonium chloride will confirm the presence of ammonia.

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Answer:

an electrolyte is a sustance that produce an electrically conducting solution when dissolved in a polar solvent , such as water

Explanation:

hope it helps

Answer:

4 millllllermeeters jb

The final concentration of the chloride ions is  0.32 M.

We know that we have to obtain the number of moles of the iron II chloride that was reacted in the solution and then we would have;

Number of moles of iron II chloride = 4.08g /127 g/mol = 0.032 moles

Given the fact that there are two chloride ions hence the amount of the chloride ions is 0.016 moles

The concentration of the silver nitrate = 50/1000  *  0.60 M

= 0.03 moles

Thus we would have a final concentration of 0.016 moles/ 0.05

= 0.32 M

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Answer:

a. boiling

Explanation:

Answer:

chemistry

Explanation:

Answer:

Chemistry

Explanation:

Answer:

The compound that is not an organic alcohol is C6H5COOH.

C3H7OH is propyl alcohol, CH3CH(OH)CH3 is 2-propanol, and (CH3)2CHCH(OH)CH2CH3 is 3-pentanol, all of which are organic alcohols.

On the other hand, C6H5COOH is benzoic acid, which is not an alcohol but an organic acid. It contains a carboxylic acid (-COOH) functional group and not the -OH functional group of alcohols.

Answer:

the correct answer would be the curvature of a lens

Answer:

0.0123 moles

Explanation:

Concentration = Moles / Volume of solution

or you can rearrange the formula to get

Moles = concentration (moles/liter)  x  volume of solution (liter)

First convert your volume to L instead of mL.  35mL = 0.035L

moles  =  0.350 moles/liter   x    0.035 liter  (liters cancel out)

moles = 0.0123

The energy difference between the third and first energy states of an electron confined in a potential well of 1 Å width depends on various factors such as the depth of the potential well and the mass of the electron.

Energy states refers to any discrete value from a set of values of total energy for a subatomic particle confined by a force to a limited space or for a system of such particles, such as an atom or a nucleus.

The excitation energy stored in excited atoms and nuclei is radiated usually as visible light from atoms and as gamma radiation from nuclei as they return to their ground states.

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Answer:

40,113 years

Explanation:

To find the age of the sample, you need to use the half-life formula:

\(N(t)=N_0(\frac{1}{2})^{t/h\)

In this formula:

------> N(t) = current mass (g)

------> N₀ = initial mass (g)

------> t = time passed (yrs)

------> h = half-life (yrs)

You can plug the given values into the equation and rearrange the formula to find "t".

N(t) = 0.781 g                       t = ? yrs

N₀ = 100 g                           h = 5730 yrs

\(N(t)=N_0(\frac{1}{2})^{t/h\)                                           <----- Half-life formula

\(0.781=100(\frac{1}{2})^{t/5730}\)                                     <----- Insert values

\(0.00781=(\frac{1}{2})^{t/5730}\)                                       <----- Divide both sides by 100

\(log_{1/2}(0.00781)=log_{1/2}((\frac{1}{2})^ {t/5730})\)               <----- Take \(log_{1/2}\) of both sides

\(7.00 = \frac{t}{5730}\)                                                   <----- Solve \(log_{1/2}\)

\(40,113 = t\)                                                   <----- Multiply both sides by 5730

The given sample is 40,113 years .

Half-life, in radioactivity, is the interval of time required for one-half of the atomic nuclei of a radioactive sample to decay.

Half-life formula,

\(\rm N(t)\;=N_0(\dfrac{1}{2})^\frac{t}{t1/2}\)   .......(1)

where,

N(t)=current mass

N₀=initial mass

t=time period

h=half -life

Given,

N(t)=0.781g, t=? yrs, N₀=100g, h=5730 years

\(\rm N(t)\;=N_0(\dfrac{1}{2})^\frac{t}{t1/2}\)

put the values, in ......(1)

0.781=100(1/2) \(t/5730\\\)

log₁/₂(0.00781)=log₁/₂ ( 1/2)\(t/5730\)

7=t/5730

40,113=t

Hence, the given sample is 40,113 years .

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The decomposition of aspirin (acetylsalicylic acid,\(C_{9} H_{8} O_{4}\)) can occur through the hydrolysis reaction, resulting in the formation of acetic acid (\(CH_{3} COOH\)) and salicylic acid (\(C_{7} H_{6}O_{3}\)).

The decomposition of aspirin (acetylsalicylic acid, \(C_{9} H_{8} O_{4}\)) can occur through the hydrolysis reaction, resulting in the formation of acetic acid (\(CH_{3} COOH\)) and salicylic acid (\(C_{7} H_{6}O_{3}\)). To determine the moles of each product formed, we need to consider the balanced chemical equation for the reaction:

\(C_{9} H_{8} O_{4} = > C_{7} H_{6}O_{3} +CH_{3} COOH\)

From the equation, we can see that for every 1 mole of aspirin, 1 mole of salicylic acid and 1 mole of acetic acid are produced.

Therefore, the moles of salicylic acid and acetic acid formed will be equal to the number of moles of aspirin that decomposes. If we know the amount of aspirin in moles, we can directly calculate the moles of each product based on stoichiometry.

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Answer:

Nitrogen is the chemical element with the symbol N and atomic number 7.

Explanation:

Answer:

The bond-dissociation energy is one measure of the strength of a chemical bond A−B. It can be defined as the standard enthalpy change when A−B is cleaved by homolysis to give fragments A and B, which are usually radical species