What are the molecular weights of the following compounds? 1. MgCl₂ 2. (NH4)SO4

Answer:

Oxygen-16 has 8 protons and 8 neutrons, and a mass number of 16. Oxygen-17 has 8 protons and 9 neutrons, and a mass number of 17. Oxygen-18 has 8 protons and 10 neutrons, and a mass number of 18.

Explanation:

Relative and average atomic mass both describe properties of an element related to its different isotopes. Out of these two Relative atomic mas is more accurate. Therefore, the average atomic mass of copper is 63.55amu.

Mass defines the quantity of a substance. It is measured in gram or kilogram. Average mass is the mass of atoms of an element that are isotopes. It can be calculated by multiplying mass of a isotope to natural abundance of that isotope.

Average atomic mass = (mass of first isotope× percent abundance of first isotope)+(mass of second isotope× percent abundance of second isotope)

Substituting the given values, we get

Average atomic mass=(  62.96  amu × 70.5% )+(64.96 amu ×29.5% )

Average atomic mass=55.58+12.27

Average atomic mass=63.55amu

Therefore, the average atomic mass of copper is 63.55amu.

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As per the balanced reaction, 4 moles or 156 g of potassium produces 2 moles or 188 g of K₂O. Hence, the mass of K required to produce 23.5 g of K₂O is 19.5 g.

Alkali metals such as sodium and potassium forms superoxide having the general formula, M₂O. These metals easily reacts with atmospheric oxygen forms their oxides.

The given reaction shows that, 4 moles of K gives 2 moles of K₂O.

atomic mass of K = 39 g/mol

mass of 4 K = 4 × 39 = 156 g

molar mass of K₂O = 94 g

mass of 2 moles = 188 g.

Hence, 156 g of K gives 188 g of potassium oxide. Thus, mass of K required to produce 23.5 g  is:

(23.5 × 156)/188 = 19.5 g.

Therefore, 19.5 g of potassium metal is required to produce 23.5 g of K₂O.

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A black precipitate is formed by the reaction; Li2S(aq) + Pb(NO3)2(aq) ------> PbS(s) + 2LiNO3(aq) and K2S(aq) + Sn(NO₃)₄(aq)→ SnS(s) + KNO₃(aq)

In a twofold decomposition reaction, the cations swap out their anion companions to form the final product. A precipitate can sometimes be produced by a twofold decomposition reaction.

A precipitate is a solid byproduct of an aqueous species reaction.

Hence, a black precipitate is formed by the reaction; Li2S(aq) + Pb(NO3)2(aq) ------> PbS(s) + 2LiNO3(aq) and K2S(aq) + Sn(NO₃)₄(aq)→ SnS(s) + KNO₃(aq)

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Insoluble sulfide compounds are generally black in color.

Which of the following combinations could yield a black precipitate?

Na2S(aq)+KCl(aq)

Li2S(aq)+Pb(NO3)2(aq)

Pb(ClO3)2(aq)+NaNO3(aq)

AgNO3(aq)+KCl(aq)

K2S(aq)+Sn(NO3)4(aq

Explanation:

The atomic mass of sulfur trioxide can be calculated as follows:

1 molecule of sulfuric acid has a mass of 98 amu, and it is composed of 2 hydrogen atoms, 1 sulfur atom, and 4 oxygen atoms. So, the mass of hydrogen and oxygen atoms in 1 molecule of sulfuric acid is (2 * 1 amu) + (4 * 16 amu) = 34 amu.

Therefore, the mass of sulfur in 1 molecule of sulfuric acid is 98 amu - 34 amu = 64 amu.

Since 1 molecule of sulfuric acid is formed from 1 molecule of sulfur trioxide, the atomic mass of sulfur trioxide can be calculated as 64 amu.

Sulfur trioxide reacts with water to form sulfuric acid according to the following reaction: SO₃ + H₂O → H₂SO₄ Given the atomic mass of hydrogen is 1 amu, the atomic mass of oxygen is 16 amu, and one molecule of sulfuric acid has a mass of 98 amu, the atomic mass of sulfur trioxide is 80 amu.

According to the law of conservation of mass, in a reaction, atomic mass of the reactants will be equal to atomic mass of the products if the reaction is balanced and above reaction is balanced. Hence,

Mass of SO₃ + Mass of H₂O = Mass of H₂SO₄

x + 18 = 98

x = 80 amu = Mass of SO₃

Therefore, when Sulfur trioxide reacts with water to form sulfuric acid according to the following reaction: SO₃ + H₂O → H₂SO₄ Given the atomic mass of hydrogen is 1 amu, the atomic mass of oxygen is 16 amu, and one molecule of sulfuric acid has a mass of 98 amu, the atomic mass of sulfur trioxide is 80 amu.

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0.248 gram of calcium ions are there in 4.13 g of CaCO3.

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.

One mole of any substance is equal to 6.023 × 10²³ units of that substance such as atoms, molecules, or ions. The number 6.023 × 10²³ is called as Avogadro's number or Avogadro's constant.

1 mole of any molecule = 6.023 × 10²³ molecules

1 mole of calcium ion = 6.023 × 10²³ molecules

Molar mass of CaCO3 = 1oogram / mole

Therefore,  4.13 g of CaCO3 of = 4.13 / 100 × 6.023 × 10²³

= 0.248 gram

Thus, 0.248 gram of calcium ions are there in 4.13 g of CaCO3.

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The half equation for this reaction is 2H2 + O2 = 2H2O and this is reduction because it is taking place in cathode.

Does cathode or anode decrease occur?

Although the direction of spontaneous electron flow in galvanic cells may be reversed in electrolytic cells, the definitions of cathode and anode where reduction takes place at the cathode and oxidation happens at the anode remain the same.

Which ions undergo cathodic reduction?

The positively charged ions will migrate toward the cathode after becoming reduced by receiving electrons. Since positive ions pick up electrons at the negative cathode, reduction takes place there.

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Answer:

To convert from Kelvin to Celsius, subtract 273 and vice versa to convert from Celsius to Kelvin.

Therefore:

298K - 273 = 24 °C

5°C + 273 = 278K

335K - 273 = 62°C

Based on the table above, the food chain Sun → grass → ground squirrel → coyote  most likely present in the prairie ecosystem. Therefore, the correct option is option B.

An ecosystem may be divided into its biotic constituents, which include all of its living members, and its abiotic constituents, which include minerals, the environment, soil, water, sunshine, and any other nonliving elements. The movement of energy through into the ecosystem as well as the cycle of nutrients inside the ecosystem are the two main factors that bind these components together.

The table below shows the organisms in a prairie ecosystem. It also shows where they get energy from. Based on the table above, the food chain Sun → grass → ground squirrel → coyote  most likely present in the prairie ecosystem.

Therefore, the correct option is option B.

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Electrons are transferred from atoms of sodium to atoms of phosphorous The sodium atom looses electron and the phosphorus atoms gains electrons.

The electron is a subatomic particle with an elementary electric charge of -1. Electrons are the first generation of the lepton particle family and are widely regarded as elementary particles due to the lack of known components or substructure.

This transfer causes the sodium atoms  to acquire positive charge and phosphorous to acquire negative charge .

Thus, the sodium and phosphorus atoms strongly attract with each other.

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Your question is incomplete, most probably, your question was

Complete the paragraph about the formation of sodium phosphide.

Electrons are transferred from atoms of

and the phosphorus atoms

to atoms of

C. This transfer makes the sodium atoms

As a result, the sodium and phosphorus atoms strongly

each other.

Water and salt is a correct combination. Therefore, the correct option is option A among all the given options.

Chemical reaction, the transformation of one or more chemicals (the reactants) into one or more distinct compounds (the products). Chemical elements or chemical compounds make up substances. In a chemical reaction, the atoms that make up the reactants are rearranged to produce various products.

Chemical reactions are a fundamental component of life itself, as well as technology and culture. Burning fuels, melting iron, creating glass as well as pottery, brewing beer, producing wine, and making cheese are just a few examples of ancient processes that involved chemical reactions. Water and salt is a correct combination.

Therefore, the correct option is option A.

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Answer: Henry's law states that the solubility of a gas in a liquid is proportional to the partial pressure of the gas over the solution. The relationship can be represented by the equation:

C = kP

where C is the concentration of the gas (in mol/L), k is the Henry's law constant, and P is the partial pressure of the gas.

Given that the mole fraction of oxygen in water is 0.210, the partial pressure of oxygen in the solution is:

P = 0.210 * 1 atm = 0.210 atm

Since the Henry's law constant for oxygen at 25 ∘C is 1.3 × 10^(-3) M/atm, the concentration of oxygen in water can be calculated as:

C = 1.3 × 10^(-3) M/atm * 0.210 atm = 0.000276 M

Finally, the mass of oxygen dissolved in 120.0 L of water can be calculated as:

mass = C * volume * molecular weight of oxygen

= 0.000276 M * 120.0 L * 32.0 g/mol

= 10.57 g

Explanation:

The density of nitrogen gas at 67.3 °C and 0.288 atm is approximately 0.0147 g/L.

Nitrogen are commonly used during sample preparation in chemical analysis and It also used to concentrate and reduce the volume of liquid sample.

The density of a gas can be calculated using the Ideal Gas Law:

PV = nRT

We can rearrange the equation to solve for the volume:

V = nRT / P

And then use the density formula:

density = mass / volume = m / V

where m is the mass of the gas and V is the volume.

Since the moles and the mass of a gas are related by its molecular weight (m = n * MW), we can substitute n * MW for m:

density = (n * MW) / V

Plugging in the values we get:

density = (n * 28.01) / (RT / P)

density = (n * 28.01 g/mol) / ((8.31 J/molK * (67.3 + 273.15 K)) / 0.288 atm)

density = (n * 28.01 g/mol) / (547.57 J/mol / 0.288 atm)

density = (n * 28.01 g/mol) / (1915.69 J/mol / atm)

density = (n * 28.01 g/mol) * (1 atm / 1915.69 J/mol)

density = 0.0147 g/L

Therefore, The density of nitrogen gas at 67.3 °C and 0.288 atm is approximately 0.0147 g/L.

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The density of the Nitrogen gas is 0.29 g/mol.

The Ideal gas law is a scientific equation that describes the behavior of an ideal gas, a theoretical gas made up of a large number of particles that do not interact with each other. The Ideal gas law states that the pressure, volume, and temperature of an ideal gas are directly proportional to each other.

Using the formula;

d = MP/RT

Density = d

Molar mass of the gas = M

Gas constant = R

Temperature = T

d= 28 g/mol * 0.288/0.082 * 340.3

d = 8.06/27.9

d = 0.29 g/mol

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Answer: 33.2 micrograms

Explanation:

We are going to convert grams to micrograms.

Step 1

Determine the conversion factors to use for converting grams to micrograms.

1 gram = 1000 milligrams

1 milligram = 1000 micrograms

Step 2

Use the number in the problem and the conversion factors to set up the problem so all conversion factors cancel except micrograms.

3.32 x 10⁻⁵ grams x (1000 milligrams/1 gram) x (1000 micrograms/1 milligram) = 33.2 micrograms/1 = 33.2 micrograms

Note that grams and milligrams cancel and you are left with micrograms. The given quantity 3.32 x 10⁻⁵ grams has 3 significant figures, so the final answer should have 3 significant figures too.

The bond that holds the amino acids is called the peptide bond and the bond is formed by the reaction between the -COOH group and the -NH2 group.

The amino acids are the compounds that can be formed by the reaction of the carbonyl group of the acid and the amide group.

Amino acids are the building blocks of proteins. They are organic compounds containing both a carboxyl (-COOH) and an amino (-NH2) group, as well as a unique side chain (R group) specific to each amino acid.

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Hydrogen gas and zinc chloride are quickly formed when zinc and hydrochloric acid interact. It is a single displacement reaction: Zn (s)+2HCl(aq), ZnCl2(aq), and H2 (g).

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The true statements are;

The reaction is endothermic

Heat is a reactant

ΔHrxn is 89 kJ/mol

Enthalpy is a thermodynamic property that represents the total energy of a system, including both its internal energy (the energy of its constituent particles) and the energy it has due to its temperature and pressure. It is commonly used in energy analysis and heat transfer calculations and is expressed in units of joules (J) or calories (cal).

We know that the enthalpy of the reaction can obtained from;

Enthalpy of the products - Enthalpy of the reactants

ΔH reaction = 2(-391.4) - 2(-435.9)

(-782.8) - (-871.8)

= 89 kJ/mol

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The units are kilojoules and calorie are used to express the energy o a system. One kJ  is 0.239 cal. Using this relation, we can convert kJ to calorie.

Energy of a system is equivalent to  the work done on the system or by the system using a force applied. The SI unit of work and energy is joule (J). One J of energy is the basic unit.

1000 joules = one kilojoule.

Other units of energy are, calorie, erg etc. The relation between one kJ and calorie unit is:

1 kJ = 0.239 calories.

Using this relation we can interconvert these two units.

For example, 20 KJ of energy is converted to calories as:

20 kJ  × 0.239 cal / 1 kJ =  4.78 calories.

Therefore, kJ of energy can be converted to cal by multiplying with 0.239.

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ilmenite, FeTiO3: 0.770 mole * (1 Ti atom / (1 FeTiO3 formula unit)) * (1 FeTiO3 formula unit / 3 Ti atoms) = 0.770 mole * (1/3) = 0.257 mole of Ti atoms.

titanium(IV) chloride, TiCl4: 0.770 mole * (1 Ti atom / (1 TiCl4 formula unit)) * (1 TiCl4 formula unit / 1 Ti atom) = 0.770 mole of Ti atoms.

Ti2O3: 0.770 mole * (2 Ti atoms / (1 Ti2O3 formula unit)) * (1 Ti2O3 formula unit / 2 Ti atoms) = 0.770 mole of Ti atoms.

Ti3O5: 0.770 mole * (3 Ti atoms / (1 Ti3O5 formula unit)) * (1 Ti3O5 formula unit / 3 Ti atoms) = 0.770 mole of Ti atoms.

An atom is the smallest unit of matter that retains the chemical properties of an element. It consists of a central nucleus made up of protons and neutrons, surrounded by electrons in orbit. The number of protons in the nucleus of an atom determines what element the atom is.

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Answer:

X(HCO3)2 is X2(C2H2O6), so the total number of atoms for each element can be calculated:

2 X atoms

4 H atoms

6 C atoms

12 O atoms

Calculate the total atomic mass of the elements:

2 X atoms * atomic mass of X = 2X * atomic mass of X

4 H atoms * 1.0 amu = 4.0 amu

6 C atoms * 12.0 amu = 72.0 amu

12 O atoms * 16.0 amu = 192.0 amu

The molar mass of X(HCO3)2 is 162 g/mol, so the total atomic mass of the elements should add up to 162 g/mol:

2X * atomic mass of X + 4.0 amu + 72.0 amu + 192.0 amu = 162 g/mol

Solve for X by rearranging the equation:

2X * atomic mass of X = 162 g/mol - 4.0 amu - 72.0 amu - 192.0 amu = -12.0 amu

2X = -12.0 amu / atomic mass of X

Divide both sides by 2:

X = -6.0 amu / atomic mass of X

So the relative atomic mass of X is 6.0 amu.

Answer: 0.112 atm.

Explanation:

(PV = nRT), which states that the pressure times volume of a gas is equal to the number of moles of gas times the ideal gas constant times the temperature.

Since the volume of the bottle is constant, we can rearrange the Ideal Gas Law to solve for pressure:

P = (nRT) / V

where

n = 0.000540 moles (the amount of O2 remaining after the candle goes out)

R = 8.31 J/mol*K (the ideal gas constant)

T = 35 + 273 = 308 K (the temperature in kelvins)

V = 250 mL = 0.25 L (the volume of the bottle in liters)

Plugging in the values, we get:

P = (0.000540 * 8.31 * 308) / 0.25

P = 0.112 atm

So, the pressure inside the bottle after the candle goes out is approximately 0.112 atm.

What causes the changes in the ice ages is when the earth's orbits tilts.

The ice ages are caused by changes in Earth's orbit and tilt, which affect the amount of solar radiation received by the planet. These changes alter the climate and trigger the growth and retreat of ice sheets.

We know that the changes in the climates is responsible for most of the changes that we can see in the universe as we have come to experience it today.

Thus the earth's orbits is what does control the changes in the ice ages.

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The statement which is true for a heating curve is that it shows how the temperature of a substance changes when heated and is therefore denoted as option B.

This is referred to as the degree of hotness or coldness of a substance and it is influenced by thermal energy with its unit being kelvin.

Heating curve on the other hand is a type of graph which shows the manner in which the temperature of a substance changes when heated as a result if the values being depicted and is therefore the reason why option B was chosen.

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Beta decay will occur in isotopes with a N/Z ratio greater than 1, which translates to an overabundance of neutrons.

Beta decay produces a new element that has one more proton and one fewer neutron while alpha decay produces a new element with some less protons and two fewer neutrons. When a nucleus from a higher energy state descends to a lower energy state and releases the excess energy through to the emission of high energy photons, this process is known as gamma decay.

Any one of three radioactive disintegration processes known as beta decay occurs when some unstable atoms spontaneously release surplus energy and undergo a shift in one unit of positive ions without changing their mass number.

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An electron get from one lobe of a p orbital because of the wave behavior of the p- orbital, electrons do not cross through the node or point of zero electron density when traveling from one lobe (positive lobe) to the other lobe (negative lobe).

The effective nuclear force of attraction is lower with p orbital electrons than with s orbital electrons. As a result, removing an electron from the s orbital requires more energy than removing an electron from the p orbital.

One orbital maximum can have two electrons. Because the s sublevel has only one orbital, it can only hold two electrons. Because the p sublevel has three orbitals, it can hold a maximum of six electrons.

Thus, Electrons can move out between orbits by releasing or absorbing energy.

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In nature, oxygen exists as a molecule. To create dioxygen, or O2, two oxygen atoms must make a covalently double bond with one another. Typically, oxygen exists as a molecule. It has the name dioxygen.

Its original definition, "the simplest form of a substance which still maintains the properties of the that substance," was intended to be encompassed by this name. "An atom is a body that can't be cut in 2; a molecule is the littlest portion of the a particular substance," wrote James Maxwell in 1873 when defining atom and molecule. Since ...

According to the contexts, this word might or might not include ions that meet this requirement. A molecule is a collection of atoms that are held together by the force of attraction known as chemical bonds.

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Answer:

keep the object away from moisture.

Explanation: