determine the enthalpy change when 18.6 g of carbon is reacted with oxygen according to the reaction: c(s) o2 (g) --> co2 (g) the change in enthalpy for this reaction is -349 kj/mol.

Answer:

Calcium atom has two valency electrons in its outermost energy level and these participate in bonding with the two of the six valency electrons in the outermost energy level of oxygen atom.

Calcium loses these two electrons and it gains a charge of +2 while Oxygen atom gains these two electrons and gains a charge of -2 hence gains stability

\(Ca {}^{2 + } \: \: and \: \: O {}^{2 - } \)

As a result, Calcium oxide is formed due to ionic or electro valent bonding.

\(CaO\)

Explanation:

mole of acid/mole of base=(concentration of acid×volume of acid)/(concentration of base×volume of base)

Na/Nb=CaVa/CbVb

1/2=(Ca×16.7)/(0.2×25)

0.2×25=2×Ca×16.7

Ca=(0.2×25)/(2×16.7)

Ca=0.15mol/dm³

mole of acid=Concentration×volume

mole of acid=0.15×(16.7/1000)

mole of acid=2.5×10^-3moles

The answer is the concentration of H₂SO₄ = 0.25 mol/L or 0.25 M.

A neutralization reaction is when an acid and a base react to form water and a salt and involves the combination of H+ ions and OH- ions to generate water.

The neutralization of a strong acid and strong base has a pH equal to 7.

The neutralization of a strong acid and weak base will have a pH of less than 7, and conversely, the resulting pH when a strong base neutralizes a weak acid will be greater than 7.

When a solution is neutralized, it means that salts are formed from equal weights of acid and base

H₂SO₄(l) + 2NaOH(l) - - - > Na₂SO₄(aq) + 2H₂O((l)

From the Equation

Mole ratio of H₂SO₄ and NaOH = 1 : 2

Molarity of Sodium Hydroxide = 0.200mol/dm3

Molarity = moles of solute/litre of solution

moles of solute = 0.200 * 25 *10⁻³

moles of  NaOH = 5 *10⁻³ moles

As Mole ratio of H₂SO₄ and NaOH = 1 : 2

moles of H₂SO₄ = 2.5 *10⁻³

So, the concentration of H₂SO₄ = 0.25 mol/L or 0.25 M.

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To prepare 500.0 mL of a 0.750 M LiBr(aq) solution, the chemist would need to use 32.6 grams of lithium bromide.

Here is the step-by-step explanation of how to calculate the mass of lithium bromide needed:

1. First, we need to convert the volume of the solution from mL to L: 500.0 mL = 0.500 L

2. Next, we use the molarity equation M = mol/L to find the number of moles of LiBr needed: 0.750 M = mol/0.500 L --> mol = 0.750 M * 0.500 L = 0.375 mol

3. Finally, we use the formula mass of LiBr to convert from moles to grams: 0.375 mol * 86.84 g/mol = 32.565 g

4. Round the answer to 1 decimal place: 32.6 g

Therefore, the chemist would need to use 32.6 grams of lithium bromide to prepare the 500.0 mL of 0.750 M LiBr(aq) solution.

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A dirty pipette that consistently causes volume measurements to be off by 0.01 ml would be an example of a systematic error, which can be minimized or eliminated by ensuring proper calibration and maintenance of equipment, as well as accurate and consistent measurement techniques.

A dirty pipette that consistently causes your volume measurements to be off by 0.01 ml would be an example of a systematic error. Systematic error is a type of error in which the measured values are consistently offset from the true values by a fixed amount in the same direction.

It is caused by a flaw in the experimental design or equipment, such as an improperly calibrated instrument, malfunctioning equipment, or poor measurement techniques.Systematic errors can be minimized by ensuring that equipment is properly calibrated and maintained, and that measurement techniques are accurate and consistent. It is important to identify and correct systematic errors in order to obtain accurate and reliable data.

In the case of a dirty pipette, the error can be eliminated by thoroughly cleaning the pipette and ensuring that it is properly calibrated before use. If the pipette is damaged or malfunctioning, it may need to be repaired or replaced to eliminate the systematic error.

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Answer:

Hallo whats up?

Explanation:

According to Charle's law, the volume of the given mass of a gas is directly proportional to its absolute temperature provided that the pressure is constant. Mathemically;

where;

V1 and V2 are the initial and final volume of the gas

T1 and T2 are the initial and final temperatures of the gas (in Kelvin)

Given the following parameters:

Substitute the given parameters into the formula;

Therefore the volume of the gas at 20°C is approximately 97.67cm³

Answer:

The liquid state sometimes is described simply as the state that occurs between the solid and gaseous states. Some examples of liquids are:

- Water

- Milk

- Vinegar

Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire available volume like a gas. Some examples of solids are:

- Rocks

- Brick

- Coin

What distinguishes a gas from liquids and solids is the vast separation of the individual gas particles. This separation usually makes a colorless gas invisible to the human observer. Some examples of gases are:

- Helium

- Oxygen

- Neon

The combined mass of hydrochloric acid and sodium hydroxide is determined by adding their individual masses.

When calculating the combined mass of hydrochloric acid and sodium hydroxide, we need to consider the individual masses of these two substances. Hydrochloric acid (HCl) has a molecular formula of HCl and consists of one hydrogen atom (H) and one chlorine atom (Cl). Sodium hydroxide (NaOH), on the other hand, is composed of one sodium atom (Na), one oxygen atom (O), and one hydrogen atom (H). To calculate the combined mass, we add the individual masses of these reactants.

The molar mass of hydrogen (H) is approximately 1 gram/mol, while the molar mass of chlorine (Cl) is approximately 35.5 grams/mol. Sodium (Na) has a molar mass of around 23 grams/mol, oxygen (O) has a molar mass of approximately 16 grams/mol, and hydrogen (H) has a molar mass of around 1 gram/mol.

To determine the combined mass of hydrochloric acid and sodium hydroxide, we multiply the number of atoms of each element by their respective molar masses and sum them up. For example, hydrochloric acid has one hydrogen atom and one chlorine atom, so the total mass would be 1 gram/mol (hydrogen) + 35.5 grams/mol (chlorine). Similarly, sodium hydroxide has one sodium atom, one oxygen atom, and one hydrogen atom, resulting in a combined mass of 23 grams/mol (sodium) + 16 grams/mol (oxygen) + 1 gram/mol (hydrogen).

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Answer:

The tectonic plates do not slowly drift over time because they are floating on a layer of liquid rock. They drift because they are sitting on a layer of solid rock (the upper mantle or "asthenosphere") that is weak and ductile enough that it can flow very slowly under heat convection, somewhat like a liquid.

Explanation:

Many scientists are dependent on the government for funding for many reasons. One of the main reasons is that research is often too expensive to carry out without the help of the government. Option b)

The government plays a major role in scientific research, especially in areas of national interest. Government research funding plays an important role in promoting scientific inquiry and advancing knowledge of the natural world. The government is in charge of allocating research funds to public and private organizations. For scientists who want to carry out their research, it can be challenging to find funding from other sources, such as private companies.

As a result, the majority of researchers rely on government grants to finance their work. This dependence on government funding has advantages and disadvantages . One of the advantages is that it ensures that scientific research is carried out in areas that are of national interest. By prioritizing funding for specific areas, the government can direct research toward those issues that are considered important to the country. Another advantage is that it can lead to more innovation. Government grants often provide funding for research that might not be carried out otherwise, such as new technologies or techniques. This can result in breakthroughs that lead to new products, services, or ideas.However, there are also some disadvantages to being dependent on government funding. One of the main drawbacks is that it can lead to a lack of independence. Researchers who rely on government grants may feel obligated to focus on areas that the government deems important, rather than pursuing their own interests or those that are considered unconventional. Another disadvantage is that government funding can be unpredictable. Grants are usually awarded for a limited period of time and may be subject to budget cuts or changes in priorities. As a result, scientists may have to constantly seek new sources of funding or may be forced to abandon their research projects. Hence option b) is correct.

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In this, each reaction involves nucleophilic substitution of SN2 mechanism at the benzylic position of benzyl bromide.

a)  Reaction of benzyl bromide with ethoxide ion forms benzyl ethyl ether as sodium ethoxide yields ethoxide ion in the reaction.

b) Reaction of benzyl bromide with tert-butoxide ion forms benzyl tert-butyl ether as potassium tert-butoxide yields tert-butoxide ion in the reaction.

c) Reaction of benzyl bromide with azide ion forms benzyl azide as sodium azide yields azide ion in the reaction.

d) Reaction of benzyl bromide with hydrogen sulfide ion forms phenylmethanethiol as sodium hydrogen sulfide yields hydrogen sulfide ion in the reaction.

d) Reaction of benzyl bromide with iodide ion forms benzyl iodide as sodium iodide yields  iodide ion in the reaction.

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Answer:

17.6510 L

Explanation:

First we should get the number of moles of helium here by Boyle's law

PV=nRT

P=750/760= 0.9868 atm

T=25+273=298 kelvin

R= 0.08206

V= 20L

so

n=PV/RT

n=0.9868×20/0.08206×298

n=0.80707 mol

Then use the same law

V=0.80707×0.08206×263/0.9869=

17.6510L

SO THE VOLUME WILL BE 17.6510 L

At the constant pressure in the balloon, the final volume of the helium gas was equal to 70.94 ml at a temperature of -10ºC.

Charles's law states that when the pressure of the gas keeps constant, the volume of the gas is directly proportional to its absolute temperature.

Therefore, V  ∝ T

or \(\frac{V_1}{T_1} =\frac{V_2}{T_2}\)                                                      .............(1)                          

Given, the initial temperature of the helium gas, T₁ = 25 ºC

The absolute temperature, T₁ = 25 + 273.15 = 298.15 K

The final temperature of the helium gas, T₂ = -10 ºC

T₂ = - 10 + 273.15 = 263.15 K

Given, the initial volume of the gas, V₁ = 20 L, and assume that V₂ is the final volume of the helium gas.

Substitute the value of V₁, T₁ and T₂ in the equation (1), we get;

\(\frac{20}{298.15} =\frac{V_2}{263.15}\)

\(V_2 = \frac{20\times 263.15}{298.15}\)

V₂ = 17.65 L

Therefore, the final volume of the helium gas is equal to 17.65 L at -10 ºC,  when the pressure in the balloon will constant.

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Answer:

This question is a practical question and hence incomplete

Explanation:

However, there are some steps that can be followed to achieve the aim of this question.

To convert millimeters (mm) to cubic centimeters (cm³), the value in millimeter will have to be divided by 1000. This is because 1 mm equals 0.001 cm³. Hence, if the volume in the data is 30 mm, the equivalent in cm³ will be

30/1000 = 0.03 cm³

OR

1 mm ⇒ 0.001 cm³

30 mm ⇒ ?

Let's assume the unknown (?) is X

1 × X = 30 × 0.001

X = 0.03 cm³

Hence, 30 mm equals 0.03 cm³

Also, to convert any volume from cubic centimeter (cm³) to square meter (m²), you will divide the unit in cm³ by 1 × 10⁶ (1,000,000). To convert the value obtained earlier (0.03 cm³ or 3 × 10⁻² cm³) to m², you will

1,000,000 cm³ ⇒ 1 m²

0.03 cm³ ⇒ ?

Let's assume the unknown (?) is Y

1000000 × Y = 0.03 × 1

Y = 0.03/1000000 OR you can write it as 3 × 10⁻² × 10⁻⁶

Y =  3 × 10⁻⁸m²

Hence, 0.03 mm equals 3 × 10⁻⁸ m²

The number of moles of NaCl = 0.103

Given

6 gram sample of NaCl

Required

moles

Solution

The mole is the number of particles contained in a substance

1 mol = 6.02.10²³

Moles can also be determined from the amount of substance mass and its molar mass

mole = mass : molar mass

Molar mass of NaCl = 58.5 g/mol

Input the value :

mole = 6 g : 58.5 g/mol

mole = 0.103

The  temperature of the water will reduce by 2.4 °C from 24.9 °C 22.5 °C.

The temperature change when 3.21 g of NH₄NO₃ is dissolved in 100 g of water under the same conditions is determined using the formula:

In example 5.6, when 3.21 g of NH₄NO₃ is dissolved in 50 g of water at 24.9°C in a calorimeter, the temperature decreases to 20.3°C.

The quantity of heat absorbed, q = -mcΔT

m = 50 + 3.21 = 53.21g

Assuming the specific heat of the solution is the same as that of water;

c = 4.18 J/g/K

ΔT = 20.3 - 24.9 = -4.6 K

q = -(53.21 * 4.18 * -4.6)

q = 1023.12 J

Since, the same mass of NH₄NO₃ is dissolved, the quantity of heat absorbed is the same.

ΔT = - q/mc

m = 100 + 3.21 = 103.21 g

ΔT = - 1023.12 J/103.21 * 4.18

ΔT = -2.4 °C

Therefore, the temperature of the water will reduce by 2.4 °C.

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The volume of the gas at STP = 35.01 L

Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure).

In general, the gas equation can be written  

\(\large {\boxed {\bold {PV = nRT}}}\)

where  

P = pressure, atm  

V = volume, liter  

n = number of moles  

R = gas constant = 0.08206 L.atm / mol K  

T = temperature, Kelvin  

V=17.4 L

T = 23 + 273 = 296 K

P = 2.18 atm

\(\tt mol=n=\dfrac{PV}{RT}\\\\n=\dfrac{2.18\times 17.4}{0.082\times 296}\\\\n=1.563\)

The volume of the gas occupy at STP :

\(\tt 1.563\times 22.4=35.01~L\)

Answer:

four

Explanation:

There is four

CH 4    methane

O2      oxygen

CO2    carbon dioxide

H20    water

Answer:

Nonrenewable

Explanation:

There is a finite supply of fossil fuels

The formula oh Hydride of of antimony is H3Sb.

Hydrides is the hydrogen anion with the the formula H-.It is the binary compound of the hydrogen with other elements .In this Hydrogen is covalently bonded. this is bonded to a less electronegative element. This only exists in extrema  condition. This consist of two electrons and a proton. Electronic configuration of hydride is 1S2.

[Kr]5s24d105p3 is antimony.

The formula of hydride in antimony is SbH3.This is a colorless gas and it is highly toxic. This is the main covalent hydride of antimony. This is also known as antimony hydride or hydrogen antimonite. This is the binary compound of Hydrogen with antimony.

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Expressing the answer in exponential form we get 3⁴.

To simplify the expression (3⁷/(3³), we can apply the properties of exponents. When dividing two exponential expressions with the same base, we subtract the exponents.

In this case, we have 3⁷ divided by 3³, which can be simplified as:

3⁽⁷⁻³⁾

3⁴

Therefore, the simplified expression is 3⁴.

To understand why we subtract the exponents when dividing, we can break down the steps.

The expression 3⁷ represents 3 multiplied by itself seven times:

3 × 3 × 3 × 3 × 3 × 3 × 3.

The expression 3³ represents 3 multiplied by itself three times:

3 × 3 × 3.

When dividing these two expressions, we can cancel out common factors by subtracting the exponents:

(3 × 3 × 3 × 3 × 3 × 3 × 3) / (3 × 3 × 3)

This simplifies to:

3 × 3 × 3 × 3

Which is equivalent to 3⁴.

Thus, the answer in exponential form is 3⁴

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The oxidation number of atoms (a) 1. (b) 6, and (c) 7 are as follows:The oxidation number of atom 1 is +8,The oxidation number of atom 6 is +5,The oxidation number of atom 7 is -2.The average oxidation number for carbon in this compound is -1.875.

The algorithm method with the formula is used to determine the average oxidation number for carbon in the compound. The formula to calculate the oxidation state of carbon can be given as:

Oxidation state of carbon = (number of carbon atoms x oxidation state of carbon) / total number of atoms.The given compound 8 N 5 2.3.4 consists of 19 atoms, of which 8 are carbon atoms, 5 are nitrogen atoms, and 6 are hydrogen atoms.

The oxidation state of nitrogen is -3 in the compound, and the oxidation state of hydrogen is +1.Now, the oxidation state of carbon is calculated as follows:

Oxidation state of carbon = (8 × oxidation state of carbon) / 19

We are supposed to find the average oxidation number of carbon atoms. To do this, we sum up the oxidation numbers of all carbon atoms and divide the sum by the total number of carbon atoms.

Oxidation state of carbon = (5* -1 + 3* -2 + 6 * +1) / 8

Oxidation state of carbon = (-5 - 6 + 6) / 8

Oxidation state of carbon = -1.875

Thus, the average oxidation number for carbon in this compound is -1.875.

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The balanced net ionic equation for the setup with a Zn electrode in a 1.0 M aqueous  Zn²⁺ solution on the left side and an Ag electrode in a 1.0 M aqueous Ag⁺ solution on the right side with a salt bridge added can be represented as follows: Zn(s) + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag(s)

In this setup, zinc metal (Zn) is oxidized and loses electrons at the anode to form zinc ions (Zn²⁺), while silver ions (Ag⁺) from the silver salt solution (AgNO₃) gain electrons at the cathode to form silver metal (Ag). The salt bridge is necessary to maintain electrical neutrality in both half-cells by allowing the transfer of anions and cations between them.

The balanced net ionic equation above represents only the species involved in the redox reaction, with the spectator ions (NO₃⁻ and Cl⁻) omitted. It also indicates the physical states of the reactants and products, with (s) representing solid, (aq) representing aqueous, and (l) representing liquid.

In summary, the balanced net ionic equation for the setup described is Zn(s) + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag(s), where zinc metal is oxidized at the anode and silver ions are reduced at the cathode, with a salt bridge facilitating the transfer of ions between the two half-cells.

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The improved telescope showed scientists that the solar system contained comets.

The solar system has to do with the arrangement of the sun and the planets. The sun lies at the center of the solar system and then the sun is surrounded by the planets that move all around the sun in concentric circles.

Now we know that the telescope is the kind of object that could be used in the study of the outer space. We could use it to study the stars as well as other celestial bodies in the study of astronomy.

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Answer:

The Earth and the Moon both rotate on an axis. They are both terrestrial objects, which means they have a solid, rocky surface. They both receive light and heat energy from the Sun.

Natural gas is primarily composed of methane (CH₄), which is a hydrocarbon gas consisting of one carbon atom bonded to four hydrogen atoms.

Methane is the main component of natural gas and typically accounts for the largest percentage of its composition. However, natural gas may also contain small amounts of other hydrocarbons such as ethane, propane, and butane, as well as traces of non-hydrocarbon gases like nitrogen, carbon dioxide, and hydrogen sulfide.

The exact composition of natural gas can vary depending on its source and processing methods. Methane is a clean-burning fuel that is commonly used for heating, cooking, and electricity generation due to its high energy content and lower greenhouse gas emissions compared to other fossil fuels.

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The board of examiners in each state is responsible for granting licensure to individuals seeking to work in certain professions. This licensure is typically granted through one of three methods: examination, endorsement, or reciprocity.

Examination involves taking a test to demonstrate one's knowledge and proficiency in the field. This is often the most common method of licensure, as it ensures that individuals have a certain level of competence before being allowed to practice. Endorsement allows individuals who have already been licensed in another state to apply for licensure in a new state without having to take another examination. This is often an option for individuals who have already demonstrated their competence and don't want to go through the entire examination process again. Reciprocity is similar to endorsement, but it involves states recognizing each other's licensing requirements and granting licensure to individuals who have met those requirements in another state. In short, the board of examiners in each state can grant licensure through any of these methods, depending on the individual's situation and the requirements of the profession.

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A radioactive substance decreases by 65% each hour. Find the hourly decay factor. The hourly decay factor is 0.35.

Chemicals in the class of radionuclides (also known as radioactive materials) have unstable atomic nuclei. They become stable by undergoing modifications in the nucleus (spontaneous fission, alpha particle emission, neutron conversion to protons, or the opposite).

A radioactive atom will naturally emit radiation in the form of energy or particles in order to transition into a more stable state. The difference between radioactive material and the radiation it emits must be made.

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The correct answer to the first part of your question is option (c): Energy is released by water vapor as it condenses.

When water vapor condenses into liquid water, it undergoes a phase change from a gaseous state to a liquid state. During this phase change, energy is released in the form of latent heat. This release of energy occurs because the water molecules in the vapor phase are more energetic and have higher kinetic energy compared to the water molecules in the liquid phase.

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