(1) (a) In an equilibrium reaction between gases Q2 and R2 to form QR, the energy content of the reactants is 100KJ and that of the product is 54KJ. The energy content of the activated complex is 210KJ. (i) Draw an energy profile diagram for the reaction. (ii) Determine the: I. activation energy of the reaction. II. enthalpy change A H of the reaction. (iii) Write a balanced equation for the reaction. (iv) State whether the reaction is exothermic or endothermic. (v) Give a reason for the answer given in 1(a)(iv). (b) (i) If sodium reacts with cold water, state ONE observation that would be made as the reaction Proceeds. (ii) Write a balanced chemical equation for the reaction in 1(a)(i) (iii) Calculate the volume of gas produced at s.t.p if 3.0g of sodium reacts with excess water. [Molar volume of gas at s.t.p = 22.4dm³; H = 1.0, O=16.0, Na = 23.0] (c) Name ONE allotrope of oxygen.​

V₂ = 6.45 mL (volume of analyte)

Here we use dilution formula, which is:

C₁V₁ = C₂V₂

where,

C₁ = initial concentration

V₁ = initial volume

C₂ = final concentration

V₂ = final volume

Given data,

C₁ = 1.0 mg/mL

C₂ = 15.5 mg/mL

V₁ = 100 mL

V₂ = ? (to be found)

Putting the values in the formula, we get:

1 × 100 = 15.5 × V₂

V₂ = 100/15.5

V₂ = 6.45 mL

A solution is diluted when more solvent is added without increasing solute. The final mixture is thoroughly mixed to make sure that every component is the same.

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The theoretical molar yield of lead (II) chloride will be 9 moles.

First, we need to look at the equation of the reaction:

[tex]Pb^{2+} + 2Cl^- --- > PbCl_2[/tex]

From the equation, the 1 mole of Pb2+ ion requires 2 moles of Cl- ion in order to produce 1 mole of lead (II) chloride.

Thus, with 18 moles Cl- ions, 9 moles of Pb2+ would be needed, instead of 12 moles. Pb2+ is simply in excess while Cl- can be said to be limiting.

Therefore, Cl- will determine how much of lead (II) chloride that will be produced. The ratio is 2 moles of Cl- to 1 mole of lead (II) chloride.

With 18 moles Cl-, 9 moles of lead (II) chloride will, thus, be produced.

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Alpha particles are identical to Helium Nuclei.

An alpha particle is subatomic particle which consist two protons and two neutrons tightly bound together. Alpha particle is identical to nucleus of helium atom. Alpha particle is a positively charged particle. Alpha particle is also known as Alpha radiation or Alpha ray.

Helium is a chemical element. The symbol of Helium is He. Atomic number of helium is 2. It is a colourless gas. Helium belongs to period 2.

Thus from the above conclusion we can say that Alpha particles are identical to Helium Nuclei.

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What is diffusion?

The diffusion of substances within a solution tends to move those substances down their concentration gradient.

Aim of diffusion:

The movement of molecules along a concentration gradient is known as diffusion. It is a significant process that all living things go through. Diffusion facilitates the flow of materials into and out of cells. Until the concentration is the same everywhere, the molecules travel from a location of higher concentration to a region of lower concentration.

Diffusion occurs in gases and liquids because random molecular movement is possible.

Types of diffusion:

Simple diffusion and facilitated diffusion are the two primary categories of diffusion.

The main aim of diffusion is to arrive at an equilibrium state. When the amount of the particles is uniformly distributed or constant throughout a solution, it is said to be in equilibrium.

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[tex]AgNO_3 + KCl[/tex] → [tex]AgCl + KNO_3[/tex] undergo a double replacement reaction and form a white, solid substance. Hence, option B is correct.

A double replacement reaction is a type of chemical reaction that occurs when two reactants exchange cations or anions to yield two new products.

Double-replacement reactions generally occur between substances in aqueous solution. In order for a reaction to occur, one of the products is usually a solid precipitate, a gas, or a molecular compound such as water.

[tex]AgNO_3 + KCl[/tex] → [tex]AgCl + KNO_3[/tex] undergo a double replacement reaction and form a white, solid substance.

Hence, option B is correct.

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It will take 14.13 years for the disintegration rate of this sample to drop to 878 disintegrations per minute.

Given that,

Half life of Sr-90 = 28.49 years

This decay process is first order decay kinetics

So according to [tex]1^{st}[/tex] order reaction

Half life = 0.693/k

k= 0.693/28.49

k= 0.0243 [tex]years^{-1}[/tex]

According to the integrated rate law for [tex]1^{st}[/tex] order reaction

ln[Rn] = ln[Rn][tex]{o}[/tex] - kt  …..(1)

where, Rn = 878 disintegrations/minute

Rn[tex]_{o}[/tex] = 1238 disintegrations/minute

Putting the values in equation (1)

ln[878] = ln[1238] - 0.0243 × t

6.7776 = 7.1212 - 0.0243 × t

0.0243t = 0.3436

t= 14.13 years

Hence, it will take 14.13 years for the disintegration rate of this sample to drop to 878 disintegrations per minute.

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The safety data sheet section which includes chemical abstract service number, european commission number and european chemical agency number are section3 and section 1 respectively.

Section 3 lists the ingredients, including stabilizers and contaminants, that are present in the product mentioned on the SDS. Information on compounds, concoctions, and any chemicals where a trade secret is asserted is provided in this section. The following details must be included in this section are Chemical Abstract Service (CAS) number and other unique identifiers.

The Safety Data Sheet(SDS's) compounds are listed in Section 1 along with suggested applications. It also offers the supplier's contact details. This section must have the following information of name, location, contact information, and emergency phone number for the manufacturer, importer, or other accountable party like European commission number and European chemical agency number.  

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Charcoal with a carbon-14 activity of 0.60 compared to new wood has less than 5,730 years.

A radioactive isotope is an element in nature that emit radioactivity in a given period of time (e.g., the half-life for C14 is equal to 5,730 years).

Radioactive dating is a technique to measure the age of an element by measuring its radioactive activity.

In conclusion, charcoal with a carbon-14 activity of 0.60 compared to new wood has less than 5,730 yr.

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1M KCl will require 25 mL to generate 100 mL of 0.25M KCl.

Molarity of a solution is defined as number of moles of solute present in 1000 mL of the solution.

[tex]M=\frac{n}{V}\times1000[/tex]

So molarity is inversely proportional to the volume of the solution.

As solution is diluted. Molarity of the solution decreases.

1M of KCl means 1 mole of KCl in 1000 mL of the solution.

1M KCl is four times as concentrated as 0.25M KCl.

Therefore, to make 100 mL of 0.25M will require [tex]\frac{100}{4}= 25 mL[/tex] of 1M KCl diluted to 100 mL of distilled water.

Easy alternative: Dilution formula

[tex]M_1\times V_1 = M_2\times V_2[/tex]

Where [tex]M_1 \,and\, V_1[/tex] are volume and concentration of first solution

and [tex]M_2\,and\, V_2[/tex] are of second solution.

[tex]1\times V= 0.25\times100\\\\V= 25\,mL[/tex]

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Answer:

d. Transition metal

Explanation:

A transition metal is an element which has an atom or forms an ion with a partially-filled d-subshell.

As we can see from the electronic configuration of Copper 2+ ion, Cu²⁺:

[tex]_{27}Cu^{2+} = 1s^2\space\ 2s^2 \space\ 2p^6 \space\ 3s^2 \space\ 3p^6 \space\ 3d^9[/tex] ,

copper forms an ion with an incomplete d-subshell that contains 9 electrons; therefore copper is a transition metal.

• Option a. is wrong because copper is not a metalloid. Metalloids have characteristics of both metals and non-metals; copper only has metallic properties.

• Option b. is wrong because 'alkaline earth metals' are the elements in Group 2 of the periodic table; copper is in Group 11.

• Option c. is wrong because 'alkali metals' are in Group 1 of the periodic table.

Answer:

b. independent/manipulated variable

Explanation:

Independent/manipulated variable - refers to the variable that is changed by the scientist or an experimenter. Only one variable that is independent is required to ensure a fair test in an excellent experiment. As the independent variable is being changed by an experimenter or scientist, data is being recorded simultaneously as they are collected.

The limiting reactant will be HCl.

They limit the amount of products produced in reactions.

From the equation, the mole ratio of Mg to HCl is 1:1.

Mole of 4.00 g mg = 4/24.3 = 0.1646 moles

Mole of 3.2 g HCl = 3.2/36.458 = 0.0878 moles

Thus, Mg is in excess while HCl is limiting in availability.

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Answer:

HCI , Excess reactant is Mg , and 4.18 g MgCl

Answer:

1,250 °C

Explanation:

To find the new temperature, you need to use a variation of the Combined Gas Law. The equation looks like this:

P₁V₁ / T₁ = P₂V₂ / T₂

In this formula, "P₁", "V₁" and "T₁" represent the initial pressure, volume, and temperature. "P₂", "V₂", and "T₂" represent the final pressure, volume, and temperature. You can find the new temperature by plugging the given values into the equation and simplifying.

P₁ = 3.00 atm                      P₂ = 1.00 atm

V₁ = 10.0 L                           V₂ = 125 L

T₁ = 300 °C                          T₂ = ? °C

P₁V₁ / T₁ = P₂V₂ / T₂                                               <----- Combined Law equation

(3.00 atm)(10.0 L) / (300 °C) = (1.00 atm)(125 L) / T₂         <----- Insert values

0.1 = (1.00 atm)(125 L) / T₂                                    <----- Simplify left side

0.1 = 125 / T₂                                                         <----- Multiply 1.00 and 125

0.1 x T₂ = 125                                                        <----- Multiply both sides by T₂

T₂ = 1,250                                                             <----- Divide both sides by 0.1

A reaction that creates larger molecules from substrates and results in water as a byproduct would be catalyzed by a synthase enzyme.

Synthase is an enzyme that catalyzes the synthesis of new compounds in the body. As a result, it is a very widespread enzyme that can be found in both higher and lower-order species. Synthases do not use energy from nucleoside triphosphates.

A synthase is a ligase that joins two chemicals or compounds together with the need for energy, whereas a synthase is a lyase that catalyzes the breakage of numerous chemical bonds through methods other than hydrolysis and oxidation.

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The gauge pressure of the oxygen in the tank in atmospheres is 11.46 atm.

The gauge pressure is given as the pressure relative to the ambient atmospheric pressure. The gauge pressure can be calculated as:

Gauge pressure = System pressure - Atmospheric pressure

The system pressure of the 35-liter tank with 18.3 moles oxygen is given as:

Pressure = moles * Rydberg constant * Temperature / Volume

Pressure = 18.3 moles * 0.08 L.atm.mol⁻¹.K⁻¹ * 298 K / 35 L

Pressure = 12.46 atm

The standard pressure is given as 1 atm.

Thus, the gauge pressure of the oxygen in the tank can be:

Gauge pressure = System pressure - Atmospheric pressure

Gauge pressure = 12.46 atm - 1 atm

Gauge pressure = 11.46 atm

The gauge pressure of the oxygen in the tank in atmospheres is 11.46 atm.

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Answer:

The answer is 8.31 atm.

Explanation:

Ideal Gas Law = PV = nRT
(where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.)

First, convert the temperature from Celsius to Kelvin:

25°C + 273.15 = 298.15 K

Next, plug in the known values into the Ideal Gas Law equation:

P * 35.0 L = 18.3 moles * 8.31 J/mol*K * 298.15 K

Finally, solve for P:

P = (18.3 moles * 8.31 J/mol*K * 298.15 K) / 35.0 L

The pressure is in units of joules per liter. To convert it to atmospheres, divide by the atmospheric pressure in joules per liter:

1 atm = 101,325 Pa = 101,325 J/m^3 = 101.325 kPa

P (in atm) = (18.3 moles * 8.31 J/mol*K * 298.15 K) / (35.0 L * 101.325 kPa)

= 8.31 atm

Answer: Mechanical Energy

Explanation:

    To produce electricity, a generator needs an input of mechanical energy. Mechanical energy is a combination of potential energy and kinetic energy. Generators use this to create electricity to power light bulbs, technological devices, and more!

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706.1652 g is the molar mass of 4.68 mol of sodium bromate.

Given:

Sodium bromate is used in a mixture which dissolves gold from its ores.

Moles of sodium bromate= 4.68 mol

Molar mass of sodium bromate = 150.89 g/mol number of moles × mol

                                                       = 150.89 × 4.68

                                                       = 706.1652 g

Therefore, 706.1652 g is the molar mass of 4.68 mol of sodium bromate.

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The number of moles (n) of O2 will be double if atmospheric pressure was doubled and all other variables stayed the same.

The general gas equation, often known as the ideal gas law, is the equation of state for a fictitious ideal gas. It has a number of limitations, but it provides a decent approximation of the behavior of numerous gases under various circumstances.

Applying the law of ideal gas: PV = nRT.

where,

P= pressure of the gas in the atm.

V= volume of the gas in L.

n = no. of moles of the gas in mol.

R = Universal gas constant,

T = temperature of the gas in K.

If V and T are constant and have different values of P and n:

(P₁n₂) = (P₂n₁).

P₂ = 2P₁,

∴ n₂ = (P₂n₁)/(P₁) = (2P₁n₁)/(P₁) = 2n₁.

therefore if we double the pressure then no. of the moles of O2 will be doubled.

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The United States was waiting for all other industrialized countries to adopt it before proceeding.

The big reasons the U.S. hasn't adopted the metric system are simply time and money. When the Industrial Revolution began in the country, expensive manufacturing plants became a main source of American jobs and consumer products so money for the installation of new system.

So we can conclude that the US was waiting for all other industrialized countries to adopt it before proceeding.

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The House of Representatives defeated the bill calling for conversion to metrics in 1974. Option B

The metric system is the most current system of measurement which is generally accepted in the scientific world. It is the system of measurement that is widely reported in scientific literature.

The reason why the United States have not officially adopted the metric system is that the House of Representatives defeated the bill calling for conversion to metrics in 1974.

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Answer:

In its organic form, metabolism is usually (not always) related with the metabolic processes of living organisms.

Explanation:

In this context, metabolism refers to how quickly a person's body consumes any fuel it consumes. Because the energy from meals is used up more rapidly when someone has a high metabolism, they require food more frequently. These folks typically feel and are warmer. A person with a high metabolism may not acquire as much weight as they would expect even if they eat more since their body uses up the food before it can be converted to fat or muscle. Consider an automobile where the accelerator has been floored. More frequent gas additions would be required, and the engine's temperature would rise. Slower metabolisms function like an idle automobile. They typically don't need to eat as frequently since their bodies use fuel more slowly. The quantity people typically consume may, however, exceed what they truly require to maintain their current state of health. They constantly use additional fuel, which tends to be stored as fat. Thus, it is not always true that everyone who is slim has a fast metabolism and everyone who is overweight has a sluggish one. It ultimately comes down to how many calories you consume against how many your body actually requires. Simply said, a person's metabolism may make or break this score relative to the norm. Therefore, those with slower metabolisms tend to put on weight quickly since they require less food than predicted to maintain their bodies whereas those with faster metabolisms prefer to be slim because of this.

The changes in matter/energy can be classified as follows:

Matter and energy undergo physical, chemical and nuclear changes.

Physical changes are changes in which no new product is formed.

Chemical changes are changes in which no new product is formed.

Nuclear changes are changes in which no new product is formed.

Examples of each of the given changes is as follows:

Therefore, matter/energy undergo changes.

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It is a limitation of the kinetic-molecular theory because closeness and low speed don't allow  intermolecular forces to become important at certain pressure and temperature.

The kinetic gas theory explains micro-particles (atoms and molecules). The kinetic theory is basically  based upon the assumption of microscopic particles . We can use it as a microscopical model.

And the kinetic theory of gases explains how gases behave by assuming that they are made up of quickly moving atoms or molecules.

Basically kinetic model is based on the below assumptions.-

I t is assumed that the gas is made by a large number of identical molecules. And molecules are moving in random directions. And also separated by the large distances as compared to their size.

The molecules collide completely elastically  without no energy loss.

Always kinetic energy is transferred between molecules through heat.

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Answer:

V2 = 0.941 L

Explanation:

This follows the Charles' law, a gas law.

Using this eq [tex]\frac{V1}{T1} =\frac{V2}{T2}[/tex]

From the given, the missing variable is V2

[tex]\frac{752 ml}{298 K} =\frac{V2}{373 K}[/tex], change ml to SI unit of Volume (L)

752 ml = 0.752 L

[tex]\frac{752 L}{298 K} =\frac{V2}{373 K}[/tex], then cross multiply

[tex]280.496 L (K) =298K (V2)[/tex]

[tex]\frac{280.496 L (K) }{298K} = (V2)[/tex]

[tex]V2 = 0.941 L[/tex]

Answer:

A. a compound that donates protons

Explanation: According to the Brønsted-Lowry definition, an acid is a substance that can donate a proton (H+ ion) to another molecule. A base is a substance that can accept that donated H+. After the Brønsted-Lowry acid donates its proton, it becomes the conjugate base of the acid.

Answer:

A: a compound that donates protons.

Explanation:

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When selecting a photometric technique that is more sensitive to a low concentration of analyte, a laboratory director compares absorbance measuring devices against those that measure fluorescence intensity. Fluorescence spectroscopy is considered more sensitive in its measurements.

Spectro-fluorometer works on the above mentioned principle...

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The specific heat of the metal is 0.30J/g°C.

The specific heat capacity is defined as the quantity of heat (J) absorbed per unit mass (kg) of the material when its temperature increases 1 K (or 1 °C), and its units are J/(kg K) or J/(kg °C).

Step 1: Data given

Mass of metal = 75.0 g

Temperature of the metal = 65°C

Mass of water = 100.0 g

Temperature of the water = 20.0°C

Final temperature of the water = 22.3 °C

The specific heat of water is 4.184 J/g°C

Step 2: Calculate the specific heat of metal

Qlost = -Qgained

Q= m xCxΔT

Qmetal = -Qwater

m(metal) x c(metal) x ΔT(metal) = - m(water) x c(water) x ΔT(water

⇒m(metal) = the mass of metal = 75.0 g

⇒c(metal) = the specific heat of the metal = ?

⇒ΔT = The change of temperature = 22.3 - 65°C = -42.7 °C

⇒m(water) = the mass of water = 100.0 g grams

⇒c(water) = the specific heat of water = 4.186 J/g°C

⇒ΔT(water) = T2 - T1 = 22.3 - 20.0 = 2.3 °C

75.0 g x c(metal) x -42.7 °C= -100.0 g x  4.186 x 2.3

75.0 g x c(metal) x -42.7 °C = −962.78

c(metal) = 0.3006338798J/g°C =0.30J/g°C

The specific heat of the metal is 0.30J/g°C.

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1. The empirical formula of the hydrocarbon is CH₃

2. The molecular formula of the hydrocarbon is C₂H₆

Mass of C = (12 / 44) × 1.47

Mass of C = 0.4 g

Mass of H = (mass of compound) – (mass of C)

Mass of H = 0.5 – 0.4

Mass of H =0.1 g

Divide by their molar mass

C = 0.4 / 12 = 0.03

H = 0.1 / 1 = 0.1

Divide by the smallest

C = 0.03 / 0.03 = 1

H = 0.1 / 0.03 = 3

Thus, the empirical formula of the compound is CH₃

Molecular formula = empirical × n = mass number

[CH₃]n = 30

[12 + (3×1)]n = 30

15n = 30

Divide both side by 15

n = 30 / 15

n = 2

Molecular formula = [CH₃]n

Molecular formula = [CH₃]₂

Molecular formula = C₂H₆

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Answer:

wheres the options?

Explanation:

-25 J is the change in internal energy, for a system that does 70 joules of work as it absorbs 45 joules of heat.

According to first law of thermodynamics energy cannot be created or destroyed but it can be changed from one form to another. First law of thermodynamics is also known as the law of conservation of energy.

Equation of first law of thermodynamics

ΔU = Q - W

where,

ΔU = Change in internal energy

Q = Heat added to the system

W = Work done by the system

Now put the values in above equation

ΔU = Q - W

      = 45 - 70

      = -25 J

Thus from the above conclusion we can say that -25 J is the change in internal energy, for a system that does 70 joules of work as it absorbs 45 joules of heat.

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if we did not use an excess of the BaCl2 solution it would decrease the mass percentage of sulfate in the unknown sample.

The net precipitation equation would be.

Ba2+(aq) + SO42-(aq)  → BaSO4(s)

If BaCl2 (Ba2+) is not taken in excess then the precipitation would not be completed as some of the sulfate ions would still be remaining in the solution. This would decrease the mass percentage of sulfate in the unknown sample.

If some tiny pieces of filter paper still remained mixed with the precipitate(BaSO4) then the mass of sulfate would increase and it gives a high mass percentage of the sulfate.

mass percentage of sulfate = (mass of sulfate/mass of sample)*100

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