A 2.15g sample of benzene (C_6H_6) is burned in a bomb calorimeter, and the temperature rises from 22.46 degree C to 34.34 degree C. Calculate the heat capacity of the bomb calorimeter. Note the following thermochemical equation: C_6H_6(I) + 15/2 O_2 (g) rightarrow 6CO_2 (g) + 3H_2O (g) Delta H degree = -3267.5 kJ

Answer:

[tex]\large \boxed {\text{24.3 g Cl}_{2}; 82.3 \%}[/tex]

Explanation:

We are given the masses of two reactants and asked to determine the mass of the product.

This looks like a limiting reactant problem.

1. Assemble the information

We will need a balanced equation with masses and molar masses, so let’s gather all the information in one place.  

MM:          86.94    36.46                 70.91

                MnO₂ + 4HCl ⟶ MnCl₂ + Cl₂ + 2H₂O

Mass/g:     86.0      50.0                  20.00

2. Calculate the moles of each reactant

[tex]\text{Moles of MnO}_{2} = \text{86.0 g MnO}_{2} \times \dfrac{\text{1 mol MnO}_{2}}{\text{86.94 g MnO}_{2}} = \text{0.9892 mol MnO}_{2}\\\\\text{Moles of HCl} = \text{50.0 g HCl} \times \dfrac{\text{1mol HCl }}{\text{36.46 g HCl }} = \text{1.371 mol HCl}[/tex]

3. Calculate the moles of Cl₂ formed from each reactant

From MnO₂:

[tex]\text{Moles of Cl$_{2}$} = \text{0.9892 mol MnO}_{2} \times \dfrac{\text{1 mol Cl$_{2}$}}{\text{1 mol MnO}_{2}} = \text{0.9892 mol Cl}_{2}[/tex]

From HCl:

[tex]\text{Moles of Cl$_{2}$} = \text{1.371 mol HCl} \times \dfrac{\text{1 mol Cl$_{2}$}}{\text{4 mol HCl}} = \text{0.3428 mol Cl}_{2}[/tex]

4. Identify the limiting reactant

The limiting reactant is HCl, because it forms fewer moles of Cl₂.

5. Calculate the theoretical yield of Cl₂

[tex]\text{ Mass of Cl$_{2}$} = \text{0.3428 mol Cl$_{2}$} \times \dfrac{\text{70.91 g Cl$_{2}$}}{\text{1 mol Cl$_{2}$}} = \textbf{24.3 g Cl}_\mathbf{{2}}\\\\\text{The theoretical yield is $\large \boxed{\textbf{24.3 g Cl}_\mathbf{{2}}}$}[/tex]

6. Calculate the percentage yield of Cl₂

[tex]\text{Percentage yield} = \dfrac{\text{Actual yield}}{\text{Theoretical yield}} \times 100 \, \%= \dfrac{\text{20.0 g}}{\text{24.3 g}} \times 100 \, \% = 82.3 \, \%\\\text{The percentage yield is $\large \boxed{\mathbf{82.3 \, \%}}$}[/tex]

Answer:

See explanation below

Explanation:

First, you are not providing any data about the mass of ice and the innitial temperature of water, so, I'm gonna use data from a similar exercise, so in order for you to get the accurate and correct answer, just replace the data in this procedure, and you should be fine.

Now, For this exercise, I will assume we have an 8 g ice cube pounded into 230 g of water. The expression to use here is the following:

q = m*Cp*ΔT (1)

Solving for ΔT:

ΔT = q / m*Cp (2)

Where:

q: heat of the water

m: mass of water

Cp: specific heat of water which is 4.18 J /g °C

Now, we don't know the heat emmited by water, we need to calculate that. To do this, we have data for ice and water, so, let's find first the heat absorbed by the melting ice, and then, the water.

Converting the grams into moles, using the molar mass of water which is 18 g/mol rounded:

moles of ice = 8 g / 18 g/mol = 0.44 moles of water

Now, we'll use the molar heat of fusion of water to convert the moles to kJ:

qi = 0.44 mol * 6.02 kJ/mol =¨2.6488 kJ

Now, as the ice is the system and water the surroundings, the melting of ice in endothermic therefore the heat of water should be the same of ice but negative, therefore:

qi = -qw = -2.6488 kJ or -2648.8 J

Finally, replace this value in equation (2) to get the temperature change:

ΔT = -2648.8 / (230 * 4.18)

ΔT = -2.75 °C

Now, use your data of ice and water and replace them here in this procedure to get the correct and accurate answer.

Answer:

Organic Material

Explanation:

Carbon Dating is the process in which the age of a piece of organic matter is determined by the proportions of carbon isotopes it contains.

Carbon dating requires that the object being tested contains carbon-14 (14C) isotopes.

Carbon-14 is a radioactive isotope of carbon that is present in the Earth's atmosphere in small amounts. Living organisms, including plants and animals, take in carbon-14 through the process of photosynthesis or by consuming other organisms.

Once an organism dies, it no longer takes in carbon-14, and the concentration of carbon-14 in its remains gradually decreases over time due to radioactive decay.

By measuring the remaining amount of carbon-14 in a sample, scientists can determine the age of an object or organism.

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Answer:

The correct answer is a A molecule that brings about a cellular response to a signal.

Explanation:

Effector molecule is a small molecule that act as ligand to generate various cellular response by binding with target proteins(receptors).

  Effector molecules can regulate catalytic activity of enzymes,gene expression and various signaling processes that are very much important for proper functioning of the cell that the effect molecule target.

 Examples Allosteric effectors which can be either modulators or inhibitors depending on the nature of the effector molecule.

Answer: The workdone W = 505J

Explanation:

Applying the pressure-volume relationship

W= - PΔV

Where negative sign indicates the power is being delivered to the surrounding

W = - 1.0atm * ( 5.88 - 0.9)L

= - 1.0atm * (4.98)

W = -4.98 atmL

Converting to Joules

1atmL = 101.325J

-4.98atmL = x joules.

Work done in J = -4.98 * 101.325

W= -505J

Therefore the workdone is -505J

Answer:

[tex]5.788\times 10^{-9} m[/tex] is the uncertainty in the position of a moving electron.

Explanation:

Heisenberg's uncertainty principle is given by the equation:

[tex]\Delta x\times m\times \Delta v=\frac{h}{4\pi}[/tex]

The mass of an electron = m

Uncertainty in velocity =  Δv

Uncertainty in position =  Δx

h = Planck's constant

We are given:

The mass of an electron = m = [tex]9.11\times 10^{-31} kg[/tex]

Uncertainty in velocity =  Δv = [tex]0.01 \times 10^6 m/s[/tex]

Uncertainty in position =  Δx

[tex]\Delta x=\frac{h}{4\pi \times m\times \Delta v}[/tex]

[tex]=\frac{6.626\times 10^{-34} Js}{4\times 3.14\times 9.11\times 10^{-31} kg\times 0.01 \times 10^6 m/s}[/tex]

[tex]=5.788\times 10^{-9} m[/tex]

[tex]5.788\times 10^{-9} m[/tex] is the uncertainty in the position of a moving electron.

The uncertainty in the position of an electron is equal to [tex]5.76 \times 10^{-9}\; meters[/tex]

Given the following data:

To find the uncertainty in the position of an electron, we would use Heisenberg's uncertainty principle:

Mathematically, Heisenberg's uncertainty principle of an object is given by the formula:

[tex]\Delta x \times m \times \Delta v = \frac{h}{4\pi }[/tex]

Where:

Making [tex]\Delta x[/tex] the subject of formula, we have:

[tex]\Delta x = \frac{h}{4\pi \times m \times \Delta v}[/tex]

Substituting the given parameters into the formula, we have;

[tex]\Delta x = \frac{6.626 \times 10^{-34}}{4\times \;3.142 \;\times \;9.11 \times 10^{-31}\; \times \;0.01 \;\times 10^{6}}\\\\\Delta x = \frac{6.626 \times 10^{-34}}{1.15 \times 10^{-25}}\\\\\Delta x = 5.76 \times 10^{-9}\; meters[/tex]

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Final answer:

To determine the time taken for the decay rate to drop from 15 to 4 disintegrations per minute using a half-life of 5730 years, we calculate that it would take two half-lives, or 11460 years, for this reduction.

Explanation:

To calculate the time it would take for a piece of wood with an initial decay rate of 15 disintegrations per minute to decrease to 4 disintegrations per minute, we can use the concept of half-life, which for carbon-14 is 5730 years. By applying the decay constant and the exponential decay formula, we can find the time that corresponds to the rate of decay reaching 4 disintegrations per minute.

The relationship we use is N = N0e-λt, where N is the final number of disintegrations per minute, N0 is the initial number of disintegrations per minute, λ is the decay constant (which can be calculated using λ = 0.693 / 5730 years), and t is the time in years.

Using the concept of half-lives, we can determine that if after t years the disintegration rate is a quarter of its original rate (15 to 4 dpm), the wood must have gone through two half-lives, because each half-life reduces the rate of disintegration by half. Therefore, t would be equal to 2 × 5730 years = 11460 years.

Answer:

1.0 L

Explanation:

Given that:-

Mass of [tex]CaC_2[/tex] = [tex]2.54\ g[/tex]

Molar mass of [tex]CaC_2[/tex] = 64.099 g/mol

The formula for the calculation of moles is shown below:

[tex]moles = \frac{Mass\ taken}{Molar\ mass}[/tex]

Thus,

[tex]Moles= \frac{2.54\ g}{64.099\ g/mol}[/tex]

[tex]Moles_{CaC_2}= 0.0396\ mol[/tex]

According to the given reaction:-

[tex]CaC_2_{(s)} + 2H_2O_{(l)}\rightarrow C_2H_2_{(g)} + Ca(OH)_2_{(aq)}[/tex]

1 mole of [tex]CaC_2[/tex] on reaction forms 1 mole of [tex]C_2H_2[/tex]

0.0396 mole of [tex]CaC_2[/tex] on reaction forms 0.0396 mole of [tex]C_2H_2[/tex]

Moles of [tex]C_2H_2[/tex] = 0.0396 moles

Considering ideal gas equation as:-

[tex]PV=nRT[/tex]

where,

P = pressure of the gas = 742 mmHg  

V = Volume of the gas = ?

T = Temperature of the gas = [tex]26^oC=[26+273]K=299K[/tex]

R = Gas constant = [tex]62.3637\text{ L.mmHg }mol^{-1}K^{-1}[/tex]

n = number of moles = 0.0396 moles

Putting values in above equation, we get:

[tex]742mmHg\times V=0.0396 mole\times 62.3637\text{ L.mmHg }mol^{-1}K^{-1}\times 299K\\\\V=\frac{0.0396\times 62.3637\times 299}{742}\ L=1.0\ L[/tex]

1.0 L of acetylene  can be produced from 2.54 g [tex]CaC_2[/tex].

About 1 liter of acetylene gas can be produced from 2.54 g of calcium carbide under the given conditions of 742 mmHg and 26C.

The question requires you to calculate the volume of acetylene gas produced from a known amount of calcium carbide using the given reaction under specified conditions. To answer this, we need to use the principles of stoichiometry combined with the ideal gas law. First, we need to convert the mass of CaC2 to moles because stoichiometry deals with mole ratios. The molar mass of CaC2 is around 64.1 g/mol so 2.54 g of CaC2 is around 0.04 moles. From the balanced equation, we can see that one mole of CaC2 produces one mole of C2H2. Therefore we also have 0.04 moles of acetylene gas produced.

Next, we use the ideal gas law (PV=nRT) to find the volume of acetylene gas produced. Here P is pressure, V is volume, n is the moles of gas, R is the ideal gas constant, and T is temperature. The pressure should be in atmospheres, so we convert 742 mmHg to around 0.97 atm. The temperature should be in kelvin, so we convert 26C to around 299K. The value for R is 0.0821 L·atm/mol·K.

Plugging in our values into the equation gives (0.97 atm x V) = (0.04 mol x 0.0821 L x atm/mol x K x 299K). Solving for V gives approximately 0.983 L or about 1 liter of acetylene gas under these conditions.

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Answer:

24.44 atm

Explanation:

Considering that this gas mixture behaves like an ideal gass, and that all component gases are ideal gases, we can use:

PV=nRT

Then:

P=nRT/V

Where:

n= N° of moles

R= gas constant= 0.082 Lt*atm/K*mol

T= temperature (in Kelvin)

V = volume (in Lt)

Finally, statement says:

T = 25°C = 298 K

V = 5 Lt

n = 8 moles (for O₂)

P = [8 molx(0.082 Lt*atm/K*mol)x298 K]/5 Lt

P = 24.44 atm would be the pressure due to O₂ (partial pressure of the oxygen)

Answer:

1122.5 mL

Explanation:

In the first scenario, by Dalton's law, the total pressure is the sum of the partial pressures of the components. So, the partial pressure of the gas is:

P1 = Ptotal - Pwater = 742 - 36 = 706 torr

By the ideal gas law, the change in a state of a gas can be calculated by:

P1*V1/T1 = P2*V2/T2

Where P is the pressure, V is the volume, T is the temperature in K, 1 is the state 1, and 2 the state 2.

P1 = 706 torr, V1 = 1350 mL, T1 = 32ºC + 273 = 305K

P2 = 760 torr, T2 = 0ºC + 273 = 273 K

706*1350/305 = 760*V2/273

760V2/273 = 3124.92

760V2 = 853102.62

V2 = 1122.5 mL

Answer: a contest in which you are eliminated if you fail to spell a word correctly.

Answer:

B

Explanation:

In counting the electron domains around the central atom in VSEPR theory, a Core level electron pair is not included.

Core level electron pair are the electrons other than the electrons in the valency shell of an atom. They in the proximity of the nucleus. They do not participate in the bonding.

VSEPR is the abbreviation for Valence shell Electron Pair repulsion theory. VESPR is a model for predicting molecular geometries based on the reduction in the electrostatic repulsion of the valence electrons of a molecule around a central atom.

Answer:

1. False

2. False

3. True

Explanation:

Identify all statements are true

1. zeroth order rate constants have units of inverse seconds. FALSE.

The rate law for a zeroth order rate reaction has the following form:

r = k

where,

r is the rate of the reaction

k is the rate constant

k has the same units than r, that is, M . s⁻¹.

2. first order reactions have half lives that are dependent on time . FALSE.

Half-life (t1/2) of a first order reaction can be calculated using the following expression.

[tex]t_{1/2}=\frac{ln2}{k}[/tex]

As we can see, half-life does not depend on time.

3. catalysts cannot appear in the rate law for a reaction. TRUE.

The rate law has the following form:

r = k . [A]ᵃ . [B]ᵇ

where,

[A] and [B] are the concentrations of the reactants

a and b are the reaction orders

Catalysts do not appear in the rate law.

When 150 ml of 0.500 M silver nitrate are added to 100 mL of 0.400 M potassium chromate, a silver chromate precipitate forms. Considering the stoichiometry of the reaction and the quantities of reactants, 24.88 grams of silver chromate will precipitate.

The subject of this question is based on precipitation reactions in Chemistry. Precipitation reactions occur when two solutions combine to form an insoluble solid known as a precipitate. The moles of silver nitrate present in a 150 mL of 0.500 M solution can be calculated using the formula Molarity = Moles ÷ Volume (in Litres).

Thus, Moles of AgNO3 = 0.500 M * 0.15 L = 0.075 mol AgNO3. According to the reaction equation 2AgNO3 + K2CrO4 → 2AgCrO4(precipitate) + 2KNO3, for every mole of K2CrO4, we have two moles of AgNO3. Thus, based on stoichiometry and the given quantities of the reactants, the limiting reactant will be AgNO3, and it will totally react and form the silver chromate precipitate. The moles of Ag2CrO4 formed would therefore also be 0.075 mol. To convert this into grams, we use the molar mass of Ag2CrO4, which is approximately 331.73 g/mol. Hence, grams of Ag2CrO4 = 0.075 mol Ag2CrO4 * 331.73 g/mol = 24.88 g Ag2CrO4.

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Explanation:

Hence, molecules of a solid have low energy.

This means that in kinetic molecular theory molecules of a gas are in rapid, random motion.

                 [tex]P\propto \frac{1}{V}[/tex]     (at constant temperature and number of moles)

                 [tex]V\propto T[/tex]     (at constant pressure and number of moles)

Thus, we can conclude that the given items are matched as follows.

1.  gas - continuously in motion.

2. solid matter - low energy.

3. Kinetic Molecular Theory - rapid, random motion.

4. Boyle's Law - relates pressure and volume.

5. Charles's Law - relates volume and temperature.

Answer:

3(NH₄)₂CrO₄ (aq)  +  2Cr(NO₂)₃ (aq)  →  6NH₄NO₂ (aq)+  Cr₂(CrO₄)₃ (aq)

Explanation:

The balanced chemical equations for the reactions are

(a) K₂O + H₂O  → 2KOH

(b) P₂O₃ + 3H₂O → 2H₃PO₃

(c) Cr₂O₃ + 6HCl → 2CrCl₃ + 3H₂O

(d) SeO₂ + 2KOH → K₂SeO₃ + H₂O

From the question

We are to write a balanced equations for the given reactions

The reaction between potassium oxide and water gives potassium hydroxide

The balanced chemical equation for the reaction between potassium oxide and water is

K₂O + H₂O  → 2KOH

The reaction between diphosphorus trioxide with water gives phosphorous acid

The balanced chemical equation for the reaction between diphosphorus trioxide with water is

P₂O₃ + 3H₂O → 2H₃PO₃

The reaction between chromium(III) oxide with dilute hydrochloric acid produces chromium(II) chloride and water

The balanced chemical equation for the reaction between chromium(III) oxide with dilute hydrochloric acid is

Cr₂O₃ + 6HCl → 2CrCl₃ + 3H₂O

The reaction between selenium dioxide with aqueous potassium hydroxide gives potassium selenite and water

The balanced chemical equation for the reaction between selenium dioxide with aqueous potassium hydroxide

SeO₂ + 2KOH → K₂SeO₃ + H₂O

Hence, the balanced chemical equations for the reactions are

(a) K₂O + H₂O  → 2KOH

(b) P₂O₃ + 3H₂O → 2H₃PO₃

(c) Cr₂O₃ + 6HCl → 2CrCl₃ + 3H₂O

(d) SeO₂ + 2KOH → K₂SeO₃ + H₂O

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A balanced reaction equation contains the same number of atoms of each element on both sides of the reaction equation.

To write a balanced chemical reaction equation, the number of atoms of each element on the right hand side must be the same as the number of atoms of the same element on the left hand side.

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Answer: C) 0.020 m

Explanation:

Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent.

[tex]Molality=\frac{n\times 1000}{W_s}[/tex]

where,

n = moles of solute  

[tex]W_s[/tex] = weight of solvent in g  

Mole fraction of [tex]CO_2[/tex] is = [tex]3.6\times 10^{-4}[/tex] i.e.[tex]3.6\times 10^{-4}[/tex]  moles of [tex]CO_2[/tex] is present in 1 mole of solution.

Moles of solute [tex](CO_2)[/tex] = [tex]3.6\times 10^{-4}[/tex]

moles of solvent (water) = 1 - [tex]3.6\times 10^{-4}[/tex] = 0.99

weight of solvent =[tex]moles\times {\text {Molar mass}}=0.99\times 18=17.82g[/tex]

Molality =[tex]\frac{3.6\times 10^{-4}\times 1000}{17.82g}=0.020[/tex]

Thus  approximate molality of [tex]CO_2[/tex] in this solution is 0.020 m

Answer:

A solution that is 0.100 M (i.e. 33,12 g of lead (II) nitrate in 1.00 L of water) yields the desired total dissolved ions concentration.

Explanation:

The molecular formula of lead (II) nitrate is Pb(NO[tex]Pb(NO_{3} )_{2}[/tex] and its molecular mass is 331,2 g/mol.

In disolution, the equilibrium will look like this:

Pb(NO[tex]Pb(NO_{3} )_{2}[/tex] -> [tex]Pb^{2+}  + 2(NO)_{3} ^{-1}[/tex]

The equation above means that, one mol of lead (II) nitrate dissolved in 1L will yield one mol of Pb ions and 2 moles of NO3 ions, i.e. 3 moles total.

If we dissolve 0.100 moles of lead (II) nitrate in 1.00 L of water, the stoichiometry of the disolution states that in turn, it will yield 0.100 of Pb ions and 0.200 moles of NO3 ions, i.e. 0.300 M in total dissolved ions.

331,2 g/mol * 0.100 mol/L * 1 L = 33,12 grams of the compound are required.

Answer:

Electromagnetic Force

Explanation:

Every aspect of chemical reaction is the output of electromagnetic force though the forces can take on many forms because of the quantum wave nature of particles.

The electromagnetic force has the ability to attract opposite charges such as protons and electrons and it repels same charges such as electrons and protons.

This force is an important force in the chemical reaction as it it is responsible for bonding between atoms. Though other forces are unique in their own way but they don't affect chemical reaction. Force of gravity is not strong enough to affect chemical reactions; when nuclear forces are involved in a reaction, such reaction is a nuclear reactor; not chemical reaction.

One of the roles of the electromagnetic force in chemical reaction is that it holds the electrons that are in the outer orbit around the nucleus; this, in the long run creates bonds with other chemical elements to create a visible matter.

The electromagnetic force is the principal force underlying all chemical reactions. It governs the interactions between charged particles in atoms and molecules, leading to the formation and breaking of chemical bonds.

The fundamental force underlying all chemical reactions is the electromagnetic force. This force is responsible for the interactions between charged particles which make up atoms and molecules. For example, in a chemical reaction, atoms or molecules rearrange to create new substances. This rearrangement involves the breaking and forming of chemical bonds, which are effectively governed by electromagnetic forces. This is due to the fact that electrons (which are negatively charged) are attracted to the nuclei of atoms (which are positively charged) which encourages them to stay within certain regions of space (creating what we know as chemical bonds).

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Answer:

These properties are basically the inverse of each other.

Explanation:

        Ionization enthalpy, is the energy required to remove an electron from                        an atom.

Ionization energy is the reverse of electronegativity. Ionization energy tells you how easily or how attracted you are to your own electrons so how hard is for somebody to steal them so it's about how much you hold on to your electrons.

Electronegativity is a chemical property and it's about how much can I steal somebody else's electrons. They are like two sides of the same coin. Electronegativity is affected by both its atomic number (number of protons in the core of an atom) and how far the valence electrons (the outermost electrons) are from the core.

Answer:

what are your statements?

According to Newton’s first law of motion,if there is no net force acting on an object that is moving at a constant 30 mph speed, the object will continue to move at 30 mph.

Option a

"Newton's first law of motion" states that an object at a stationary position or an object moving at a constant velocity continues its state of rest or of motion unless it is acted upon by an "external unbalanced resisting force".

Since the net force acting on this object is zero; the absence of any kind of force (neither internal nor external) is observed and hence the motion at constant 30 mph velocity will continue until it is resisted.

Answer:

The sample of indium, has an average atomic mass of 114.818 amu

Explanation:

Step 1: Data given

Indium is made of 95.7 % 115In and 4.3% 113In

113In has an atomic mass of 112.904 amu

115In has an atomic mass of 114.904amu

Step 2: Calculate the average atomic mass

The average atomic mass = X

0.957* 114.904 + 0.043* 112.904 = X

109.963 + 4.855 = X

X = 114.818

The sample of indium, has an average atomic mass of 114.818 amu

Rounded to the nearest tenth, the average atomic mass of indium is approximately 114.9 amu. So, the correct options provided is:C

To calculate the average atomic mass of a sample of indium, you can use the following formula:

Average Atomic Mass = (% abundance of isotope 1 × atomic mass of isotope 1) + (% abundance of isotope 2 × atomic mass of isotope 2) + ...

In this case, you have two isotopes of indium, 115In and 113In, with the following information:

- % abundance of 115In = 95.7%

- % abundance of 113In = 4.3%

- Atomic mass of 115In = 114.904 amu

- Atomic mass of 113In = 112.904 amu

Plug these values into the formula:

Average Atomic Mass = (0.957 × 114.904 amu) + (0.043 × 112.904 amu)

Calculate each part:

Average Atomic Mass = (110.009648 amu) + (4.855672 amu)

Now, add these values together:

Average Atomic Mass = 114.86532 amu

Rounded to the nearest tenth, the average atomic mass of indium is approximately 114.9 amu. So, the correct options provided is:C

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Answer:

1)50.007 grams of an isotope will left after 10 years.

1)25.007 grams of an isotope will left after 20 years.

3) 23 half-lives will occur in 40 years.

Explanation:

Formula used :

[tex]N=N_o\times e^{-\lambda t}\\\\\lambda =\frac{0.693}{t_{\frac{1}{2}}}[/tex]

where,

[tex]N_o[/tex] = initial mass of isotope

N = mass of the parent isotope left after the time, (t)

[tex]t_{\frac{1}{2}}[/tex] = half life of the isotope

[tex]\lambda[/tex] = rate constant

We have:

[tex][N_o]=100 g[/tex]

[tex]t_{1/2}=10 years[/tex]

[tex]\lambda =\frac{0.693}{t_{1/2}}=\frac{0.693}{10 year}=0.0693 year^{-1}[/tex]

1) mass of isotope left after 10 years:

t = 10 years

[tex]N=N_o\times e^{-\lambda t}[/tex]

[tex]N=100g\times e^{-0.0693 year^{-1}\times 10}=50.007 g[/tex]

2) mass of isotope left after 20 years:

t = 20 years

[tex]N=N_o\times e^{-\lambda t}[/tex]

[tex]N=100g\times e^{-0.0693 year^{-1}\times 20}=25.007 g[/tex]

3) Half-lives will occur in 40 years

Mass of isotope left after 40 years:

t = 40 years

[tex]N=N_o\times e^{-\lambda t}[/tex]

[tex]N=100g\times e^{-0.0693 year^{-1}\times 40}=6.2537 g[/tex]

number of half lives = n

[tex]N=\frac{N_o}{2^n}[/tex]

[tex]6.2537 g=\frac{100 g}{2^n}[/tex]

[tex]n\ln 2=\frac{100 g}{6.2537 g}[/tex]

n = 23

23 half-lives will occur in 40 years.

Because we do not know if the value of the change in free energy will be positive or negative.  It is not possible to determine without more information.

Option E

Heat Energy is simply defined as an energy that is moved from one body to another using the concept of difference temperature changes.

Generally, the equation for the change in enthalpy  is mathematically given as

ΔG = ΔH - T ΔS

In conclusion, we do not know the magnitude of positive or positive value and hence, we do not know if the value of the change in free energy will be positive or negative.

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C3.

Tes

Example 8

Name each ionic compound.

CaCl2

AlF3

Co2O3

Solution

Using the names of the ions, this ionic compound is named calcium chloride. It is not calcium(II) chloride because calcium forms only one cation when it forms an ion, and it has a characteristic charge of 2+.

The name of this ionic compound is aluminum fluoride.

We know that cobalt can have more than one possible charge; we just need to determine what it is. Oxide always has a 2− charge, so with three oxide ions, we have a total negative charge of 6−. This means that the two cobalt ions have to contribute 6+, which for two cobalt ions means that each one is 3+. Therefore, the proper name for this ionic compound is cobalt(III) oxide.

Test Yourself

Name each ionic compound.

Sc2O3

AgCl

Answers

scandium oxide

silver chloride

How do you know whether a formula—and by extension, a name—is for a molecular compound or for an ionic compound? Molecular compounds form between nonmetals and nonmetals, while ionic compounds form between metals and nonmetals. The periodic table (Figure 3.2 “A Simple Periodic Table”) can be used to determine which elements are metals and nonmetals.

There also exists a group of ions that contain more than one atom. These are called polyatomic ions. Table 3.7 “Common Polyatomic Ions” lists the formulas, charges, and names of some common polyatomic ions. Only one of them, the ammonium ion, is a cation; the rest are anions. Most of them also contain oxygen atoms, so sometimes they are referred to as oxyanions. Some of them, such as nitrate and nitrite, and sulfate and sulfite, have very similar formulas and names, so care must be taken to get the formulas and names correct. Note that the -ite polyatomic ion has one less oxygen atom in its formula than the -ate ion but with the same ionic charge.

Table 3.7 Common Polyatomic Ions

Name Formula and Charge  Name Formula and Charge

ammonium NH4+  hydroxide OH−

acetate C2H3O2−, or CH3COO− nitrate NO3−

bicarbonate (hydrogen carbonate) HCO3− nitrite NO2−

bisulfate (hydrogen sulfate) HSO4− peroxide O22−

carbonate CO32− perchlorate ClO4−

chlorate ClO3− phosphate PO43−

chromate CrO42− sulfate SO42−

cyanide CN− sulfite SO32−

dichromate Cr2O72− triiodide I3−

The naming of ionic compounds that contain polyatomic ions follows the same rules as the naming for other ionic compounds: simply combine the name of the cation and the name of the anion. Do not use numerical prefixes in the name if there is more than one polyatomic ion; the only exception to this is if the name of the ion itself contains a numerical prefix, such as dichromate or triiodide.

Writing the formulas of ionic compounds has one important difference. If more than one polyatomic ion is needed to balance the overall charge in the formula, enclose the formula of the polyatomic ion in parentheses and write the proper numerical subscript to the right and outside the parentheses. Thus, the formula between calcium ions, Ca2+, and nitrate ions, NO3−, is properly written Ca(NO3)2, not CaNO32 or CaN2O6. Use parentheses where required. The name of this ionic compound is simply calcium nitrate. Write the proper formula and give the proper name for each ionic compound formed between the two listed ions. cause the ammonium ion has a 1+ charge and the sulfide ion has a 2− charge, we need two ammonium ions to balance the charge on a single sulfide ion. Enclosing the formula for the ammonium ion in parentheses, we have (NH4)2S. The compound’s name is ammonium sulfide.

Because the ions have the same magnitude of charge, we need only one of each to balance the charges. The formula is AlPO4, and the name of the compound is aluminum phosphate.

Neither charge is an exact multiple of the other, so we have to go to the least common multiple of 6. To get 6+, we need three iron(II) ions, and to get 6−, we need two phosphate ions. The proper formula is Fe3(PO4)2, and the compound’s name is iron(II) phosphate.

Test Yourself

Write the proper formula and give the proper name for e

Answer: check explanation.

Explanation:

The three elements/metals, that is Calcium, Barium and Magnesium all belongs to group 2A on the periodic table. Other elements/metals of group 2A in the periodic table are; Beryllium, Strontium and Radium.

As one go down the group, the atomic radius increases from Magnesium to Barium(this is because of the increase in number of shells of electrons). And, as one go down the group the first ionization energy decreases.Because of this decease in ionization energy it makes it easier for the valence electrons to be removed and thus, REACTIVITY INCREASES DOWN THE GROUP.

Ca^2+ + 2OH^- --------> Ca(OH)2.

Mg^2+ + 2OH^- ---------> Mg(OH)2.

PS: The Na^+ is a spectator ion.

Answer:

85%

Explanation:

Firstly, we will need to calculate the molar mass of the molecule. We simply use the atomic masses of each of the elements. The atomic masses are as follows:

C = 12

H = 1

O = 16

N = 14

S = 1

All units are in a.m.u

The molecular mass is thus:

(135 × 12) + (96 × 1) + (16 × 9) + 14 + 32 = 1906g/mol

The percentage by mass of carbon = (135 × 12)/1906 × 100% = 85%

Final answer:

The percentage by mass of carbon (C) in coal, given the formula C135H96O9NS, is approximately 84.97%.

Explanation:

To calculate the percentage by mass of carbon (C) in coal using the approximate formula C135H96O9NS, we first need to determine the molar mass of the entire compound, and then compare it to the mass of just the carbon atoms within the compound. The atomic masses for C, H, O, N, and S are roughly 12.01 g/mol, 1.008 g/mol, 16.00 g/mol, 14.01 g/mol, and 32.07 g/mol, respectively.

To find the molar mass of C135H96O9NS:

C: 135 atoms × 12.01 g/mol = 1621.35 g/mol

H: 96 atoms × 1.008 g/mol = 96.768 g/mol

O: 9 atoms × 16.00 g/mol = 144.00 g/mol

N: 1 atom × 14.01 g/mol = 14.01 g/mol

S: 1 atom × 32.07 g/mol = 32.07 g/mol

The total molar mass of the coal formula is therefore 1621.35 + 96.768 + 144.00 + 14.01 + 32.07 = 1908.198 g/mol.

To calculate the percentage of carbon in the compound:

Percentage of C = (Mass of C / Molar mass of compound) × 100

Percentage of C = (1621.35 g/mol / 1908.198 g/mol) × 100 ≈ 84.97%

Therefore, the percentage by mass of carbon in coal for this given formula is approximately 84.97%.

Explanation:

The given data is as follows.

     mass = 0.158 g,      volume = 100 ml

     Molarity = 1.0 M,      [tex]\Delta T[/tex] = [tex](32.8 - 25.6)^{o}C = 7.2^{o}C[/tex]  

The given reaction is as follows.

         [tex]Mg(s) + 2HCl(aq) \rightarrow MgCl_{2}(aq) + H_{2}(g)[/tex]  

So, moles of magnesium will be calculated as follows.

         No. of moles = [tex]\frac{mass}{\text{molar mass}}[/tex]                            

                               = [tex]\frac{0.158 g}{24.305 g/mol}[/tex]

                               = [tex]6.5 \times 10^{-3}[/tex]

                               = 0.0065 mol

Now, formula for heat released is as follows.

              Q = [tex]m \times C \times \Delta T[/tex]

                  = [tex]\text{volume} \times \text{density} \times C \times \Delta T[/tex]

                  = [tex]100 ml \times 1.0 g/ml \times 4.184 \times 7.2^{o}C[/tex]

                  = 3010.32 J

Hence, heat of reaction will be calculated as follows.

            [tex]\Delta H_{rxn} = \frac{\text{-heat released}}{\text{moles of Mg}}[/tex]

                      = [tex]\frac{3010.32 J}{0.0065 mol}[/tex]

                      = -4.63 J/mol

or,                  = [tex]-463 \times 10^{-5} kJ/mol[/tex]                (as 1 kJ = 1000 J)

Thus, we can conclude that heat of given reaction is [tex]-463 \times 10^{-5}[/tex] kJ/mol.    

Answer:

v = 37.9 ml

Explanation:

Given data:

Mass of compound = 1.56 kg

Density = 41.2 g/ml

Volume of compound = ?

Solution:

First of all we will convert the mass into g.

1.56 ×1000 = 1560 g

Formula:

D=m/v

D= density

m=mass

V=volume

v = m/d

v =  1560 g / 41.2 g/ml

v = 37.9 ml

The volume of the compound is 37.86 mL.

Volume is the capacity of an object.

To calculate the volume of the compound, we use the formula below.

Formula:

Where:

make v the subject of the equation

From the question,

Given:

Substitute these values into equation 2

Hence, the volume of the compound is 37.86 mL.

Learn more about volume here: https://brainly.com/question/1972490

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