In a chemical hot pack, iron powder and oxygen react to form iron oxide in the presence of a catalyst. This reaction causes the temperature of the hot pack to increase. This process is

Answer:

B.) 0.316

Explanation:

To find the moles, you need to multiply the given value by the molar mass. The molar mass is made up of each element's atomic mass times their quantities. It is important to arrange the conversion in a way that allows for the cancellation of units.

Atomic Mass (S): 32.065 g/mol

Atomic Mass (O): 15.998 g/mol

Molar Mass (SO₃): 32.065 g/mol + 3(15.998 g/mol)

Molar Mass (SO₃): 80.059 g/mol

25.3 grams SO₃                1 mole
-------------------------  x  -------------------------  =  0.316 moles SO₃
                                    80.059 grams

The resistance of the heating element is 21.61 Ω

Given

The power dissipated = 1500 W

Voltage = 180 V

We know that

Power = Voltage * Current

⇒ Power / Voltage = Current

⇒ 1500 W/180 V = Current

⇒ 8.33 A = Current

In order to calculate the resistance of the heating element. We Have to apply the formula

Power = (Current)^2 * Resistance

⇒ Resistance = Power / (Current)^2

⇒ Resistance = 1500 W/ (8.33) ^2

⇒ Resistance = 21.61 Ω

Hence the resistance of the heating element is 21.61 Ω

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There are  0.138 gram  copper could be electroplated on the cathode in an experiment where an average of 200 ma was passed through the cell for 35 minutes .

Calculation ,

Given ; Current passed through copper ( I ) = 200 mA =  200×[tex]10^{-3}[/tex] A

time in second = 35 minutes×60 = 2100 sec

Current ( I )= Q/t

Q =It =  200×[tex]10^{-3}[/tex] A  × 2100 sec  = 420 C

96500 C of charge =  1 mole

420 C of charge =  1 mole ×420 C/ 96500 C = 0.00435 mol

In  , the valancy of Cu is +2 .

2 moles of electron  are required for the decomposition of 1 mole of Cu on the cathode .

0.00435 mol  of electron  are required for the decomposition of Cu =  1mol × 0.00435 mol/2 = 0.002175 mol of Cu

Number of moles of Cu = given mass / molar mass

Mass of Cu = Number of moles of Cu × molar mass = 0.002175 ×63.546

Mass of Cu = 0.138 gram

Therefore , mass of copper is  0.138 gram

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A pure element unbound or in a diatomic state, such as cl2, always has an oxidation number of 0 (zero).

In a neutral substance with atoms of only one element, the oxidation number of an atom is zero. As a result, the oxidation number of the atoms in O2, O3, P4, S8, and aluminum metal is 0. The oxidation numbers for an element in its normal state will be zero. O2 and Cl2 are diatomic gas molecules that occur naturally, thus when they are in that state, they have an oxidation state of zero. Metals like zinc will also have an oxidation number of zero if they are in their natural solid state.

O2 and Cl2 are neutral diatomic, hence they will always have a zero oxidation state. It is impossible for one oxygen atom to have a negative 2 charge while the other has a positive 2. The oxidation states should be 0 if the elements are solids, liquids, or any type of diatomic molecule.

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option (d) 0 is the right option.

A pure element unbound or in a diatomic state, such as cl2, always has an oxidation number of 0.

An unbound or diatomic pure element, like cl2, always has an oxidation number of 0 (zero).

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There are  1.554 moles are in the sample of gas when a  gas has a volume of 27. 5 L at 302 K and 1. 40 atm.

Calculation,

The given question is solved by the using of ideal gas equation which is shown below.

PV = nRT                               .... ( i )

where , P is he pressure of the gas = 1. 40 atm

V is the volume occupied by the gas = 27.5 L

R is the universal gas constant = 0.082 L atm/K mol

T is the temperature =  302 K

n is he number of moles of the gas = ?

By putting the value of pressure  P , volume V , Universal gas constant and temperature T in the equation ( i ) we get the number of moles.

1. 40 atm × 27.5 L = n × 0.082 L atm/K mol×  302 K

n = 1. 40 atm × 27.5 L/0.082 L atm/K mol×  302 K = 1.554 mole

There are  1.554 moles are in the sample of gas

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The relationship between the light emitted by an atom and the energies of the electrons in the atom is that the energy emitted by an atom is equal to the difference between the energy of two orbitals.

According to Bohr's model:

In Bohr's theory, the electron can jump from a lower energy level to a higher energy level, and when the energy is removed electron comes back to the initial energy level. Bohr proposed the energy and radii of an electron in the atom are quantized.

Energy between the orbits is given by,

∆E = E -E°

where ∆E = difference between the energy of orbital.

E = initial energy

E° = final energy.

Thus, we concluded that the energies of electron in the atom is equal difference between the energy of two orbitals.

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Answer:

136 g Al₂O₃

Explanation:

Assuming you do not need to find the limiting reactant, to find the mass of Al₂O₃, you need to (1) convert grams O₂ to moles O₂ (via molar mass), then (2) convert moles O₂ to moles Al₂O₃ (via mole-to-mole ratio from equation coefficients), and then (3) convert moles Al₂O₃ to grams Al₂O₃ (via molar mass). It is important to arrange the conversions in a way that allows for the cancellation of units. The final answer should have 3 sig figs to match the sig figs of the given value (64.0 g).

Molar Mass (O₂): 32 g/mol

Molar Mass (Al₂O₃): 102 g/mol

4 Al + 3 O₂ -----> 2 Al₂O₃

64.0 g O₂           1 mole           2 moles Al₂O₃            102 g
-----------------  x  --------------  x  ------------------------  x   -------------  =  136 g Al₂O₃
                             32 g               3 moles O₂             1 mole

Answer:

Explanation:

Based of the fact that you were given 2 masses I would assume this to be a limiting reagent question. However amount on the left side both equal 2. Ignoring limiting reagents and focusing on just O2 the steps would be:

1. Make sure the equation is balanced ( already given)

2- Use given values to find the mols of O2 (mass/molar mass)

3. Mols are conserved but due to the coefficients the molar value from O2 must be divided by three and multiplied by 2 to ensure proper ratios

4. Using that amount the mass can derived using amount/molar mass

5. Use proper significant digits and units(3 in this case)

Fe is the limiting reactant.

The balanced chemical equation between iron and oxygen to produce iron (III) oxide is

4Fe(s) + 302(g) - ---> 2Fe2O3(s)

Mass of Fe = 227.8 g

Moles of Fe = 227.8gFe*Imol Fe/55.85g Fe = 4.079mol Fe

Mass of oxygen = 128 g

Moles of O2 = 128g02 * 1molo/32g02 = 4molO2

Calculating the limiting reactant: The reactant that produces the least amount of product will be the limiting reactant.

Mass of iron (III) oxide produced from Iron = 4.079mol Fe*2molFe2O3/4molFe*159.69g Fe2O3/1 mol Fe2O3 = 325.7gFe2O3

Mass of iron (III) oxide produced from oxygen = 4molO2 *2mol Fe2O3/3molO2*159.69gFe2O3/1mol Fe2O3 = 425.84gFe2O3

Iron (Fe) produces the least amount of the product iron (III) oxide. So, Fe is the limiting reactant.

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Answer:

Explanation to the following:

A glow stick will glow longer at lower temperatures than at room temperature, one can infer from the observation. Temperature and reaction time are the test variables.

We notice in this reaction that a glow stick stored in the freezer lights for a longer period of time than a glow stick stored at normal temperature. This implies that temperature affects how long a response lasts.

The most straightforward explanation for this observation is that glow sticks glow longer in colder temperatures than they do at room temperature; as a result, glow sticks kept in the freezer are observed to glow longer than glow sticks kept at room temperature.

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The external expression of a mineral’s orderly internal arrangement of atoms is referred to as its crystal form

Internally, a mineral's crystal structure, or regular, repeating arrangement of atoms, reflects the chemical makeup of the mineral. A CHEMICAL FORMULA, which only lists the proportions of the various elements and groups of elements in the mineral, can be used to describe the composition of a mineral. For minerals with a narrow range of composition, the latter idea—groups of elements—comes into play. Color, hardness, luster, crystal formations, density, and cleavage are characteristics that aid geologists in determining a mineral's identity in a rock. The atomic structure of a crystal essentially determines its form, cleavage, and hardness. Chemical composition is the main determinant of color and density.

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Answer:

3.3 x 10⁻¹⁷ Hz    

Explanation:

To find the frequency, you can use the following equation:

E = h / f

In this equation,

-----> E = energy (J)

-----> h = Planck's Constant (6.626 x 10⁻³⁴ J*s)

-----> f = frequency (Hz)

You can plug the given values into the equation and simplify to find the frequency. This equation will require a little bit of rearranging.

E = h / f                                                        <----- Given equation

(2.0 x 10⁻¹⁷ J) = (6.626 x 10⁻³⁴ J*s) / f         <----- Insert values

(2.0 x 10⁻¹⁷ J) x f = (6.626 x 10⁻³⁴ J*s)        <----- Multiply both sides by f

f = 3.3 x 10⁻¹⁷ Hz                                        <----- Divide both sides by 2.0 x 10⁻¹⁷

The frequency of an x-ray wave with an energy of 2.0 x 10^-17 J is 3.3 x 10⁻¹⁷ Hz.

The term frequency is defined as the number of waves that pass a fixed point in unit time. Frequency is measured in hertz which is equal to one event per second.

Frequency also describes the number of cycles undergoes during one unit of time by a body in periodic motion.

Calculating the frequency, you can use the following equation:

E = h / f

Where,

E = energy (J)

h = Planck's Constant (6.626 x 10⁻³⁴ J*s)

f = frequency (Hz)

Insert his values in the given equation

(2.0 x 10⁻¹⁷ J) = (6.626 x 10⁻³⁴ J × s) / f        

(2.0 x 10⁻¹⁷ J) x f = (6.626 x 10⁻³⁴ J × s)        

f = 3.3 x 10⁻¹⁷ Hz                

Thus, The frequency of an x-ray wave with an energy of 2.0 x 10^-17 J is 3.3 x 10⁻¹⁷ Hz.

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4 ml stock is needed for the standard of 1 mg/ml creatinine if a 4.0 mg/dl creatinine standard is needed to prepare 100 ml of the working standard.

Your muscles produce creatinine as a waste product during routine, everyday action. In a typical state, your kidneys remove creatinine from your blood and excrete it in urine. Creatinine can accumulate in the blood and less creatinine will be excreted in the urine if there is an issue with your kidneys.

A high amount of creatinine in the blood or urine may indicate that the kidneys are not doing a good job of filtering the blood. Although high creatinine levels do not pose a life-threatening hazard, they may be a sign of a major health problem, such as chronic renal disease.

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The nature of ions formed by different atoms is as follows:

Ions are substances which are formed when neutral atoms gain or lose electrons.

There are two types of ions based on the charge the ion carries;

The nature of the ions formed by different atoms depend on whether the atoms are atoms of metals or atoms of non-metals.

Metal atoms form positively-charged ions by the loss of one or more electrons as illustrated below:

where; M is a metal atom, M⁺ is a metal ion, and e⁻ is an electron.

Non-metal atoms form negatively-charged ions by the gain of one or more electrons as illustrated below:

where; N is a non-metal atom, N⁻ is a non-metal ion, and e⁻ is an electron.

In conclusion, the nature of ions formed by atoms depends on the nature of the atom, whether they are metallic or non-metallic atoms.

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The coefficient of performance (cop) of a refrigerator is defined as the ratio of " the work necessary to heat or cool something usefully."

The usable heating or cooling delivered to work required ratio, also known as the coefficient of performance, or COP, of a heat pump, refrigerator, as well as air conditioning system. Higher efficiency, less energy (power) usage, and thus reduced operational costs are all related to higher COPs.

Coefficient of performance formula:

[tex]K = Q_{H} / W_{in}[/tex]

where, K = Coefficient of performance, [tex]Q_{H}[/tex] = heat of pumps output, [tex]W_{in}[/tex] = work required by the system.

It is refrigeration's coefficient of performance (COP) will always be greater than 1.

Therefore, the coefficient of performance (cop) of a refrigerator is defined as the ratio of " the work necessary to heat or cool something usefully."

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Na -k pumps couple atp hydrolysis with the transport of Na and k.

Both ions are used for active transport.

d. K+ and Na+ both diffuse into the cell along their concentration gradients and drive the transport of glucose.

Na/K pump is a pump located on the plasma membrane which uses ATP to move 3 Na ions out the cell and brings in 2 K ions into the cell. It is an example of primary active transport. As a consequence, concentration of Na is higher outside the cell, while K concentration is higher inside the cell.

Glucose is transported in the cell against its gradient, together with Na ions (symport) which move down their concentration gradient.

This is an example of secondary active transport because it uses the energy from the primary active transport to move other substances such as glucose against their own gradients.

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The half-life of sr-89 will be 51 days.

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0.6 mol / L is the molarity of a solution prepared by dissolving 36. 0 g of NaOH in enough water to make 1. 50 l of solution.

The amount of a substance in a specific volume of solution is known as its molarity (M). The number of moles of a solute per liter of a solution is known as molarity. The molar concentration of a solution is another term for molarity.

The ratio employed to indicate the solution's concentration is called its molarity. Understanding a solution's molarity is important since it allows you to determine the actual concentration as well as whether the solution is diluted or concentrated.

Amount of NaOH = 36. 0 g

Amount of water = 1. 50 L

1 mol of NaOH = 40 g,

Moles of NaOH = 36. 0 / 40 g = 0.9 mol NaOH

Molarity of a solution = moles of solute / Liters of solution

Molarity of a solution = 0.9 / 1.50

Molarity of a solution = 0.6 mol / L

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The pH of the solution is 12.88.

millimoles of NaOH = volume x Molarity

                                 = 24.00 mL x 0.25 M

                                 = 6.00 mmole

millimoles of HCl = 24.00 mL x 0.10 M

                            = 2.40 mmole

Total volume = 48.00 mL

                            NaOH + HCl   →     NaCl + H2O

initial                       6.00      0               0         0

added                                 2.40

change                   -2.40  -2.40      +2.40  +2.40

equilibrium               3.60    0           2.40    2.40

The pH is determined by the excess of NaOH present.

[NaOH] = millimoles/volume

            = 3.60/48.00

            = 0.075 M

pOH = -log (OH⁻).

        = -log (0.075)

        = 1.12

Then

pH + pOH = pKw = 14.00.

pH = 14 - pOH

pH = 14 - 1.12

pH = 12.88

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Answer:

C. C-14 decays but C-12 stays the same after death.

Explanation:

C-12 is stable and won't change.  C-14 is slightly radioactive.  It decays over time to C12.  A living plant or animal has a fairly constant C14/C12 ratio during it's lifetime.  Sources of food have a fairly consistent C-14/C-12 ratio.  Once it dies, the C-14 is no longer replenished, so the ratio of C-14 to C-12 drops over time, giving paleontologists the ability to carbon-date the sample.  The less C-14, the older the sample.

Molality of ethylene glycol, C₂H₄(OH)₂, in a solution prepared from 2. 331×10³ g of ethylene glycol and 2.00×10³ g of water, H₂O is 47.6m

Ethylene Glycol is known as C₂H₄(OH)₂. It is added in water to prepare an Antifreeze solution.

Given,  

Mass of Ethylene Glycol = 2.331 × 10³ g = 2.331kg

Mass of Water = 2.00 × 10³ g

Since, Ethylene Glycol is in excess. Hence, it acts as a solvent and water acts as a solute.

We know, Molar Mass of Water = 18g

Hence, Moles of  Water = Given mass of water / Molar Mass of Water

⇒             Moles of  Water = 2000 / 18

⇒            Moles of  Water = 111.1

Molality is defined as the moles of solute present in a given solvent in kg.

∴ Molality = Moles of  Solute / Mass of Solvent (in kg)

Molality = Moles of  Water / Mass of Ethylene Glycol

⇒ Molality = 111.1 / 2.331

⇒ Molality = 47.6m

Molality of ethylene glycol, C₂H₄(OH)₂, in a solution prepared from 2. 331×10³ g of ethylene glycol and 2.00×10³ g of water, H₂O is 47.6m

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Explanation:

The similarities between chemical and physical changes include change in state of matter and both process involve change in energy.

Chemical changes of a substance results in the formation of entirely new substances. These changes are not reversible.

Physical changes results in the change of the state of the substance which can be reversed.

However, both chemical and physical changes results in change of state of matter and both process results in change in energy.

Thus, we can conclude that the similarities between chemical and physical changes include change in state of matter and both process involve change in energy.

(it's alre answered but here it again 'NOTE: not my answer')

The molar mass of the compound is 68 g/mol.

The Osmotic pressure can be obtained from the relationship;

π= iCRT

π= osmotic pressure = 28.1 mmHg or 0.037 atm

i = Vant Hoff factor = 1

C = concentration = ?

R = gas constant = 0.082 atmLK-1Mol

T = temperature = 20°c + 273 = 293 K

C = π/iRT

C =  0.037/1 * 0.082  * 293

C = 0.0015 M

Now;

Number of moles = C/V = 0.0015/100 * 10^-3

= 0.015 moles

Number of moles = mass/molar mass

Molar mass =  mass/Number of moles = 0. 102 g/ 0.015 moles = 68 g/mol

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Based on the calculations, the total pressure of the final products is equal to 1.76 atm.

From the information provided about this chemical reaction, we can logically deduce the following parameters:

Next, we would write the properly balanced chemical equation for this chemical reaction:

                               I₂ + 5F₂   ⇒  2IF₅

Also, we would determine the number of moles of each atom of I₂ and F₂:

[tex]Number \;of \;moles = \frac{mass}{molar\;mass}[/tex]

Substituting the given parameters into the formula, we have;

Number of moles = 63.45/253.8

Number of moles = 0.25 moles.

Assuming I₂ were limiting, we would need:

5 × 0.25 = 1.25 moles of F₂.

For fluorine gas, we have:

PV = mRT/MM

Mass, m = PVMM/RT

Mass, m = 2.5(5.00)(38)/(0.0821 × 298)

Mass, m = 475/24.4658

Mass, m = 19.42 grams.

Number of moles = 19.42/38

Number of moles = 0.51 moles.

The total number of moles = 0.25 + 0.51 = 0.76 mol.

For the mole fraction of I₂, we have:

Mf = 0.25/0.76

Mole fraction = 0.33.

For the mole fraction of F₂, we have:

Mole fraction = 1 - 0.33 = 0.67.

Next, we would determine the total pressure of the two elements by applying Dalton's law:

Total pressure = 0.33 × 0.27 + 0.67 × 2.5

Total pressure = 1.76 atm.

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Answer:

0.453 moles

Explanation:

The Ideal Gas Law equation looks like this:

PV = nRT

In this formula,

-----> P = pressure (atm)

-----> V = volume (L)

-----> n = moles

-----> R = Ideal Gas Constant (0.08206 atm*L/mol*K)

-----> T = temperature (K)

To find the amount of moles of gas, you can plug the given values into the equation and then simplify.

P = 2.7 atm                                 R = 0.08206 atm*L/mol*K

V = 4.2 L                                     T = 305 K

n = ? moles

PV = nRT

(2.7 atm)(4.2 L) = n(0.08206 atm*L/mol*K)(305 K)

11.34 = n(25.0283)

0.453 = n

Typically, amides will hydrolyze under milder conditions than esters.

So, second option is correct one.

In acidic medium, amide interact with the water molecules to give a carboxylic aid and salt of ammonia or amine salt whereas in a basic medium, amides interacts with water molecules to give carboxylic aid and salt of ammonia or amine salt. An amides will hydrolyze under milder conditions because amide is least reactive than ester. The electronegativiy of nitrogen is less than oxygen. So, nitrogen transfer more electron cloud than oxygen towards carbonyl carbon. So, carbonyl group of amide hydrolysis in milder condition than ester.

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Answer:

D. carbohydrate, blue-purple

Explanation:

Carbohydrates are one of many types of macronutrients found in certain foods and drink. For example, sugars, starches, and fibers are carbohydrates.

When starch is present, using an iodine solution will turn it blue-black or purple. If starch is NOT present, it will stay orange or yellow. The reason starch reacts with iodine is due to the amylose present in starch. Iodine is not soluble in water, so it's dissolved along with potassium iodide that forms a triiodide molecule. That then enters the helical structure of amylose and changes its color.

Answer:

An increase in the intensity of sounds or fire issuing from a relief valve.

Propane serves as the propellant in all aerosols. R-12, a Freon that was the previous propellant, has been outlawed because it harms the ozone layer above the poles. Propane and R-12 share the same pressure-temperature characteristics.

Propane's boiling point is quite low. It desires a boil-off at ambient temperature. And it continues to do so until the pressure inside a closed container rises to roughly 150 psi (give or take depending on temperature), at which time the boiling point is raised high enough to cause the substance to stop boiling.

"Contents Under Pressure" is exactly what the notice indicates. Paint, hairspray, lubricant, wasp and hornet spray, among other liquids, can be found within an aerosol can, which is a pressure vessel. By inspecting the bottom, you may determine whether a vessel is a pressure vessel. If it is dished in like a bowl, it has the same pressure-holding end as a huge propane tank, with the exception that the curve on the latter has an outward orientation. On aerosol canisters, it is inward because they must sit upright for ease. A circular bottom just cannot accomplish that. But the top resembles an outer hemisphere more or less.

Thank you,

Eddie

For calculating mean value, add up all of the values then divide by the number of them. 815/9 is about 90.6

The mean refers to the average of a set of values. The mean can be computed in a number of ways, including the simple arithmetic mean (add up the numbers and divide the total by the number of observations), the geometric mean, and the harmonic mean.

Moreover, the mean can be used to represent the typical value and therefore serves as a yardstick for all observations. For example, if we would like to know how many hours on average an employee spends at training in a year, we can find the mean training hours of a group of employees.

Hence, the mean can be calculated only for numeric variables, no matter if they are discrete or continuous. It's obtained by simply dividing the sum of all values in a data set by the number of values.

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