What were the 3 missing elements in the periodic table?

Answer:

a) Double replacement

b) Synthesis

Explanation:

a) For A, we have two ionic reactants that form two ionic products, where the anion (or cation) is swapped. This is a characteristic of a double replacement reaction.

b) For B, two elements, this time two elements, react together to form one product that's unlike the reactants. This is a characteristic of a synthesis reaction.

The concentration of the HCl solution is 0.816 M (or 816 mM).

To determine the concentration of the HCl solution, we can use the balanced equation for the neutralization reaction between HCl and NaOH:

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)

This reaction is a neutralization reaction, which means that the number of moles of H+ ions (from the HCl) is equal to the number of moles of OH- ions (from the NaOH).

Given that 20.4 mL of a 1 M NaOH solution was needed to completely react with 25 ml of HCl, we can use the volume and molarity of the NaOH solution to determine the number of moles of OH- ions:

Molarity = moles of solute/litres of solution

Moles of OH- = (20.4 mL x 1 M) / 1000 mL/L = 0.0204 moles

Since the number of moles of H+ ions is equal to the number of moles of OH- ions, we can use the number of moles of OH- to determine the number of moles of H+ ions:

moles of H+ = moles of OH- = 0.0204 moles

We can then use the number of moles of H+ ions and the volume of the HCl solution to determine the concentration of the HCl solution:

Molarity = moles of solute/litres of solution

concentration of HCl = moles of H+ / (25 mL / 1000 mL/L) = 0.0204 moles / 0.025 L = 0.816 M (or 816 mM)

Therefore, the concentration of the HCl solution is 0.816 M (or 816 mM).

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22.3 g of NaN₃ are required to fully inflate an airbag of 11.5 L at STP.

Chemical decomposition, also known as chemical breakdown, is the process of breaking down a single chemical entity into two or more components. Chemical breakdown is commonly thought of and characterized as the inverse of chemical synthesis. When one reactant breaks down into two or more products, this is referred to as a decomposition reaction. This is expressed by the following generic equation: AB A + B. The breakdown of hydrogen peroxide to water and oxygen is an example of a decomposition process, as is the breakdown of water to hydrogen and oxygen.

Here,

In airbags, sodium azide decomposes to form sodium and nitrogen gas, which inflates the bag. The decomposition reaction is:

2 NaN₃ ⇒ 2 Na + 3 N₂

We can calculate the mass of NaN₃ needed to produce 11.5 L of N₂ at STP, using the following relations.

At STP, 1 mole of N₂ occupies 22.4 L.

The molar ratio of N₂ to NaN₃ is 3:2.

The molar mass of NaN₃ is 65.01 g/mol.

=11.8*1/22.4*2/3*65.01/1

=118/112*21.67

=22.82 g

22.3 g of NaN₃ are required to fully inflate an airbag of 11.5 L at STP.

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The number of moles of MgCO3 that is present in the given mass of magnesium carbonate is 2.99 moles.

The number of moles can be defined as the ratio of given mass over molar mass. The chemical that is given is magnesium carbonate having molar mass of 84.314 g/mol and the given mass of the same is 252.939 grams.

The formula for number of moles that is 'n' can be given as follows:

n= m/M where m is the given mass and M is the molar mass.

Substituting the values,

n= 252.939 grams /84.314 grams/mol

n=2.99 moles

Therefore, the number of moles of MgCO3 is 2.99 moles.

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Explanation:

use to describe something that is complete opposite

When 200 grams of water cools from 50.0°C to 250°C, the total amount of heat energy released by the water is The total amount of energy released is 20, 930 J.

We will apply the formula. q = mCt, where q is the amount of heat energy released. m= mass. C is the specific heat of the water. T= temperature change. Because the specific heat of the water has not been specified, we will use the standard value of 4.186J/g °C. q = mCΔT. q = 200 × 4.186 × (50 -25) (50 -25) q = 200 × 4.186 × 25 q = 5000 × 4.186 q = 20, 930 The total amount of energy released is 20, 930 J.

In physics, energy (from Ancient Greek: v, enérgeia, "activity") is a quantitative property that is transferred to a body or a physical system and is visible in the performance of work as well as in the form of heat and light. Energy is a conserved quantity, which means that it can be converted in form but not created or destroyed. The joule is the SI unit of energy measurement (J).

The kinetic energy of a moving object, the potential energy stored by an object (for example, due to its position in a field), the elastic energy stored in a solid object, and the chemical energy associated with chemical reactions are all common types of energy.

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The three elements that are highly reactive belongs to alkali metals i.e., s-block elements that are lithium, sodium and potassium.

The elements that belongs to s block elements are hydrogen (H), lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). The nature of alkali metals is soft and shiny in appearance. They have low melting point and are highly reactive in nature and usually tarnish when exposed to air. Sodium (Na) is the most reactive element since it's valence electrons are not tightly held together in the atom. The three elements that are highly reactive are Lithium (Li), Sodium (Na), and potassium (K). The elements toward the bottom left corner of the periodic table are the metals that are the most active in the sense of being the most reactive

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The pressure in the container can be calculated using Ideal gas law. The pressure of the gas at the reduced temperature will be 0.17 atm.

Ideal gas law states the relation between volume, pressure, temperature and number of moles of a gas as written below:

PV = nRT.

Where R is the universal gas constant equal to 0.082 L atm/ K mol.

Given , T = 100 K

n = 0.13 moles

V = 6.1 L

Then, P = nRT/ V

The pressure of the gas at 100 K with 0.13 mole is calculated as follows:

P = (0.13 mole × 100 K × 0.082 L atm/ K mol) / 6.1 L = 0.17 atm.

Therefore, the pressure of the gas is 0.17 atm.

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a) The balanced equation is :

C₂H₆   +  Cl₂ --->  C₂H₅Cl  + HCl

b) The percent yield is the 83.0 % %.

a) The balanced equation  is given below :

C₂H₆   +  Cl₂ --->  C₂H₅Cl  + HCl

b) mass of the ethane = 300 g

molar mass of the ethane = 30 g/mol

moles of the ethane = 300 / 30

                                  = 10 mol

mass of chlorine = 650 g

molar mass of the chlorine = 71 g /mol

moles = 650 / 71

          = 9.15 mol

it is clear the the chlorine is the limiting reactant.

1 mole of the chlorine produces the 1 mole of the C₂H₅Cl

moles of the C₂H₅Cl = 9.15 mol

mass of the C₂H₅Cl = 9.15 × 64.5

                                  = 590.175 g

The percent yield = (experimental yield / theoretical yield )  × 100 %

                              = ( 490 / 590 .175 ) × 100 %

                              = 83.0 %

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The conclusion is supported by these results is binding of oxygen to the protein changes the protein's tertiary structure to a conformation that resists the effects of urea.

Fluorescence is a property that some chemicals have that allows them to emit visible light after absorbing radiation that is typically invisible, like ultraviolet light.

Fluorescence is the name given to the process of electromagnetic radiation typically visible light emitting from a material as a result of atoms being excited. These excited atoms almost immediately (within 10⁻⁸ seconds) begin emitting again. In most cases, the initial excitation is brought on by the energy absorption of incident radiation or particles, like X-rays or electrons.

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Answer:

By the process of evaporation

Explanation:

decentralized multinational corporations, centralised global corporations, international companies, and transnational enterprises.

The molarity of 2. 50 m NaCl solution is 2.68 molal and 48. 2 percent by mass KBr solution is 7.82 m.

Molality = moles solute / kg solvent  

Assume we have 1000 ml of solution.

1000 ml ₓ 1.08 g/ml = 1080 g

Now find the mass of NaCl:

2.50 M NaCl = 2.50 mol/L and 2.50 mol/L x 1 L = 2.50 moles of NaCl

molar mass NaCl = 58.4 g/mol, therefore mass NaCl present = 2.50 mol ₓ 58.5 g/mol = 146 g NaCl

Now find the mass of H₂O:

grams H₂O present = 1080 g - 146 g = 934 g H2O = 0.0.934 kg

We now have moles NaCl and kg H₂O

Molality  = 2.50 mol / 0.934kg = 2.68 molal

48.2% by mass of KBr means 48.2 g KBr / 100 g solution

To find molality, we need moles of KBr and kg of H₂O.  We can easily find he moles of KBr from the mass and the molar mass.

If we have 100 g solution, 48.2 g is KBr so the rest is H₂O.

100 g - 48.2 g = 51.8 g H₂O and this is equal to 0.0518 kg H₂O

Moles KBr = 48.2 g KBr ₓ 1 mol KBr/119 g = 0.405 moles KBr

Molality = 0.405 moles KBr / 0.0518 kg H₂O = 7.82 m

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The percent yield of water vapor is 1000%, which is not possible and this is an indication that the experiment has not been done accurately or there is an error in the data, or the reaction is not a complete reaction.

To calculate the percent yield of a reaction, you need to know the theoretical yield (the maximum amount of product that could be produced based on the balanced equation) and the actual yield (the amount of product that was actually produced in the lab). To find the theoretical yield, you can use the balanced equation for the reaction and the amount of reactant that was used.

The balanced equation for the decomposition of iron(III) hydroxide is:
Fe(OH)3 --> Fe2O3 + H2O

We are given that 8.0 g of Fe(OH)3 was used in the reaction.
From the balanced equation, we can see that for every 1 mole of Fe(OH)3 that reacts, 1 mole of H2O is produced.

The molar mass of Fe(OH)3 is 106 g/mol
so the amount of moles of Fe(OH)3 is 8.0 g / 106 g/mol = 0.075 moles

The theoretical yield of H2O would then be 0.075 moles.

We also know that 0.75 L of H2O is isolated at STP, which is equivalent to 0.75 moles of H2O.

The percent yield can be calculated by dividing the actual yield by the theoretical yield, and multiplying by 100%.

% yield = (actual yield / theoretical yield) * 100%

% yield = (0.75 moles / 0.075 moles) * 100%
% yield = 10 * 100%
% yield = 1000%

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Use the grams to moles formula to calculate the number of moles, n, of a substance with a given mass, m, (in grams) accurately, where M denotes the substance's molar mass. Typically, g/mol is used as the unit.

n = m / M

The mole is the SI unit used to measure a substance's quantity. There are precisely 6.02214085774× 10²³ atoms, molecules, or other particles in one mole of matter. The Avogadro number is this enormous magnitude. A mole of a substance is defined as a mass of material that contains exactly 12,000 g of 12C's exact number of atoms as fundamental units. The International System of Units uses the mole (symbol: mol) as the unit of material quantity (SI). 

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Answer:

Explanation:

They are Covalent networks solids

As the air gets warmer it rises because,  particles spread out making it less dense. The diffusing capability of gas molecules make it possible.

Intermolecular force are the force that keep the particles of a substance binded together. Gaseous molecule easily diffuse in air , since the intermolecular attraction is very less in them.

In solid state molecules are densely packed and difficult to move apart. In liquid state , particles have some space to move and in gases molecules are far apart due to less intermolecular force.

As the gas molecules in air absorbs heat energy, they overcome all the intermolecular forces and will spread out in the air. Thus, they rises above over a temperature gradient.

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If the density of blood is 1.060 g/mL, then the mass of 6.56 pints of blood is 3.29 grams.

The density of a substance is the measure of how densely it is packed together. It is expressed as mass per unit volume. Symbol for density: D or Formula for Density: = m/V, where is the density, m is the object's mass, and V is the object's volume. Density is the amount of things (people, animals, plants, or items) in a given area. To compute density, divide the number of items by the area measured. A country's population density is the number of inhabitants divided by its area in square kilometers or miles.

Here,

6.56 pints  * 473.1765 ml/pint  * 1.060 g/ml = 3.290  gm

The mass of 6.56 pints of blood is 3.29 grams if the density of blood is 1.060 g/mL.

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A carbonyl group is bound to hydrogen bond or to a hydrogen ion and an alkoxy substituent in an organic compound known as an aldehyde.

Aldehyde is an organic compound containing a functional group with the structure −CHO, in which a carbon atom is double-bonded to an oxygen atom and single-bonded to a hydrogen atom. Aldehydes are the simplest type of carbonyl group and the most common type of organic compound. Aldehydes are found in many natural and manufactured products, including perfumes and food products. The most common example of a natural aldehyde is formaldehyde, which is produced by plants and animals.

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A neon sign contains 2.01 x 10^25 atoms of gas. 3.34 x 10^-3 moles of neon are in the sign.

The term mole is defined as the amount of substance of a system which contains as many elementary entities.

1 mole is equal to 6.023 × 10 ²³ molecules.

According to Avogadro's constant, in one mole, there are 6.02 x 10^23 atoms.

To calculate how many moles are in 2.01 x 10^21 atoms, you would divide it by the amount of atoms that fit in a mole.

2.01 x 10^21 atoms / 6.02 x 10^23

= 0.00334 moles,

= 3.34 x 10^-3 moles

Thus, A neon sign contains 2.01 x 10^25 atoms of gas. 3.34 x 10^-3 moles of neon are in the sign.

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Your question is incomplete, most probably your question was

A neon sign contains 2.01 X 1021 atoms of the gas. How many moles of neon are in the sign?

a1.21 X 1045 mole Ne

b3.34 X 10-3 mole Ne

c2.00 X 102 mole Ne

d12.10 X 102 mole Ne

H₂ (g) + O₂ (g) ⇒ H₂O (g) because Hydrogen and oxygen gas both exist as diatomic molecules. The water is in gaseous state due to the heat given off by the combustion reaction.

Combustion, often known as burning, is a high-temperature exothermic redox chemical reaction that occurs between a fuel and an oxidant, typically atmospheric oxygen, to generate oxidized, generally gaseous products in a mixture known as smoke. A combustion reaction is a type of chemical reaction that occurs when any combustible component reacts with an oxidiser to generate an oxidised product. Fires and the release of energy in the form of heat are frequently associated with combustion processes. A hydrocarbon generally combines with oxygen in most combustion processes to produce carbon dioxide and water.

Here,

Because hydrogen and oxygen gas exist as diatomic molecules, H2 (g) + O2 (g) = H2O (g). Because of the heat produced by the combustion reaction, the water is in a gaseous condition.

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The coefficient of ammonia in the above chemical equation is 3.

A chemical equation is said to be balanced when the number of the atoms involved in the reactants side is equal to the number of atoms in the products side.

Balancing chemical equations involves the addition of stoichiometric coefficients to the reactants and products.

According to this question, ammonia reacts with oxygen gas to produce nitrogen oxide and water as follows:

4NH₃ + 50₂ → 4NO + 6H₂O

Based on the above balanced equation, it can be said that the coefficient of ammonia is 4.

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The more stable carbocation that forms through a 1,2-shift is a tertiary carbocation.

A 1,2-shift is a rearrangement of a carbon-carbon double bond, where one of the carbons moves two positions away from its original location with its original bonding partner following it. This creates a carbocation intermediate, with the carbon that moved being the positively charged center. Since tertiary carbocations are the most stable of the carbocation intermediates, the more stable carbocation that forms through a 1,2-shift is a tertiary carbocation.

The more stable carbocation that forms through a 1,2-shift is a tertiary carbocation.

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A 7.5 10-3 M Ba(OH)2 solutions at 25°C has a pH of 1.82. (option b).

A homogenous solution of two or more ingredients with particles smaller than one nm is referred to as a solution. Solutions come in many forms, such as soda water, salt and sugar solutions, etc. In a solution, every element appears as a single phase.

In chemistry, a solution is a homogeneous mix of two or more molecules in relative proportions that can be constantly changed up to what is known as the limit of solubility. Although the term "solution" is frequently used to refer to the liquid state of matter, solutions of gases and solids are also possible.

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a weak acid. The Ka (acid dissociation constant) is a measure of the strength of an hydrofluoric acid in solution. It is defined as the equilibrium constant for the dissociation reaction of the acid in water,.

which is usually written as:

HA + H2O → H3O+ + A-

A lower Ka value indicates that the acid is a weak acid, meaning that it does not dissociate very well in water and thus has a low concentration of H3O+ ions. A higher Ka value indicates that the hydrofluoric acid is a strong acid, meaning that it dissociates very well in water and thus has a high concentration of H3O+ ions. Given that the Ka for hydrofluoric acid is 7.2 x 10-4, this means that hydrofluoric acid is a weak acid. This means that it does not dissociate very well in water and thus has a low concentration of H3O+ ions. It is a weaker acid than the strong acids like Hydrochloric acid, Sulfuric acid, Nitric acid and many others.

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The empirical and molecular formula of benzene is CH and C6H6 that contains only carbon and hydrogen and the mass of hydrogen is 7.74%.

Molar mass of benzene is = 78.1%

Hydrogen = 7.44%

We have to find empirical and molecular formula

We calculate the percentage of Carbon in the compound is as follow:

Percentage of compound = 100%

Hydrogen = 7.44%

We have find the percentage of carbon

Carbon = (Percentage of compound) - (Hydrogen)

= 100-7.44

= 92.56%

Calculate empirical formula:

Carbon (C) = 92.56%  Hydrogen (H) = 7.44% Empirical formula = ?

Firstly, divide by their molar mass

C = 92.56 / 12 = 7.71, H = 7.44 / 1 = 7.44

Divide by the smallest

C = 7.71 / 7.74 = 1, H = 7.44 / 7.44 = 1

Empirical formula of benzene = CH

Calculate Molecular formula

Molecular mass of benzene = 78.1 g / mol. Empirical formula = CH, Molecular formula = ?

Molecular formula = Empirical formula  X n

Molecular formula = molar mass

Therefore, Empirical formula x n = molar mass

[CH]n = 78.1, [12 + 1]n = 78.1,

13n = 78.1

Divide both sides by 13

n = 78.1 / 13

n = 6

Molecular formula = C6H6

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After solving the equation: The half-life for this reaction is 0.693/0.271 = 2.56 s.

Reaction is the response of a system to an external or internal stimulus. It is the way a person or object behaves in response to a change in their environment. Reactions can be physical, chemical, or psychological. Physical reactions involve changes in the body, such as muscle tension, sweating, or heart rate.

The half-life for this reaction is the time it takes for the concentration of molecular iodine to decrease by a factor of 2, or for half of the original amount of molecular iodine to react. This can be calculated using the equation:

T1/2 = 0.693/k

where k is the first-order rate constant.

Therefore, the half-life for this reaction is 0.693/0.271 = 2.56 s.

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Answer:

because I'm the reactivity table of metals it shows that iron is indeed more reactive than copper

Explanation:

potassium (most reactive)

sodium

lithium

calcium

magnesium

aluminum

zinc

iron

tin

lead

hydrogen

copper

mercury

silver

gold( least reactive)

On the basis of arrangement of atoms, the matter is classified into three states: solid, liquid and gas.

In Chemistry, there are three fundamental states of matter based on the arrangement of molecules and atoms inside it.

Generally, solids have strict and rigid arrangement of atoms as they posses strong intermolecular forces and have high melting and boiling points. solids have fixed composition of atoms.

Similarly, liquids have loose arrangement of atoms and molecules keep moving randomly in a liquid. Liquids have low melting and boiling points as compared to solids. Gases have weakest intermolecular forces and atoms are arranged randomly in them. Also, their molecules keep moving in all directions.

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