A___ change occurs when a substance changes phase.

Answer:

11) the difference in heat energies between products and reactants

12) enthalpy change

Explanation:

The heat of reaction is defined as that energy released or absorbed as chemical substances participate in a chemical reaction. It is a term used to denote the change in energy as reactants change into products.

Another name of heat of reaction is enthalpy of reaction. It is a state function since it depends on the initial and final states of the system.

Answer:

pH < 7; pH = 7; pH > 7

Explanation:

when dealing with an acidic base, you have the formula for [H3O+] > [OH-] which yields a pH < 7.

when you have a neutral base, the reactive ion concentration would be [H3O^+] = [OH^-] which yields a pH = 7.

finally, when dealing with a basic classification, the formula would be [H3O^+] < [OH^-] yields a pH > 7.

The density of the rock as we have it is 7.11 g/mL.

We know that when we talk about the density of the object we are talking about the ratio of the mass of the object to the volume of the object. In the case that we have here we know that the  rock weighing 32.0g is placed in a graduated cylinder displacing the volume from 12.3mL to 16.8mL.

Volume of the rock is the volume of the fluid that has been displaced by the rock as such we have;

Density = mass/ volume

= 32.0 g/16.8 mL - 12.3 mL

= 7.11 g/mL

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The volume of hydrogen gas is 67.2L (Option -B)

A chemical reaction known as an oxidation-reduction (redox) reaction includes the exchange of electrons between two substances. Any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by acquiring or losing an electron is referred to as an oxidation-reduction reaction. Many fundamental processes of life, such as photosynthesis, respiration, combustion, and corrosion or rusting, depend on redox reactions.

Now, the reaction of Reduction of Boron trichloride from hydrogen is

\(2BCl_{3}+3H_{2}\rightarrow2B+3HCl\)

Now, it is clear that \(2\) moles of boron chloride reacts with \(3\\\) moles of hydrogen gas to give \(2\) moles of boron and \(3\\\) moles of hydrogen chloride.

So,

Atomic mass of boron is \(10.8g\)

Mass of \(2\) moles of boron \(=2\times10.8=21.6g\)

Which states that \(3\) moles of hydrogen gas reacts with \(2\) moles of boron chloride to give \(21.6 g\\\) of boron.

By avogadro hypothesis, \(1\) mole take \(22.4L\) of volume

\(3\) moles will occupy \(=3\times22.4L=67.2L\).

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Answer:

pH of buffer solution is 7.0

Initial pH of Weak acid is 3.27

Final pH of weak acid is 3.07

Amount of NaOH added is 1ml

Explanation:

Titration is a process in which acid and base are introduced together until a neutral solution is achieved whose pH value is near to buffer solution which is 7.0, the pH value for acid is below 7 while pH value for base is above 7.

Answer:

False

Explanation:

Hope I helped! Love, Josie.

A combustion reaction is a reaction that reacts in the presence of oxygen molecules. Methane will release -3115 kJ/mol of heat.

A combustion reaction includes the reaction between the chemical reactant and oxygen molecule to produce the product. The combustion reaction between methane and oxygen is given as:

CH₄(g) + 2O₂ (g) → CO₂(g) + 2H₂O (l), ΔH = -890 kJ/mol

The stoichiometry coefficient from the reaction gives 1 mole of methane releases -890 kJ/mol enthalpy.

So, 3.5 moles methane will release = 3.5 × -890 = -3115 kJ/mol

Therefore, -3115 kJ/mol of heat is released.

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Answer:

No entendí porfavor puedes explicarme

The grams of magnesium hydroxide needed to yield 8.00 moles of magnesium chlorate is approximately 466.64 g. None of the options provided match the calculated value of 466.64 g.

To determine the grams of magnesium hydroxide (Mg(OH)2) needed to yield 8.00 moles of magnesium chlorate (Mg(ClO3)2), we need to consider the balanced chemical equation for the reaction between magnesium hydroxide and chlorine.

The balanced equation is as follows:

2 Mg(OH)2 + 6 Cl2 → 2 Mg(ClO3)2 + 2 H2O

From the balanced equation, we can see that 2 moles of Mg(OH)2 react with 6 moles of Cl2 to produce 2 moles of Mg(ClO3)2.

Therefore, the stoichiometric ratio is 2 moles of Mg(OH)2 : 2 moles of Mg(ClO3)2.

To calculate the grams of Mg(OH)2 needed, we can use the stoichiometric ratio and the given moles of Mg(ClO3)2.

Given:

Moles of Mg(ClO3)2 = 8.00 moles

Using the stoichiometric ratio, we have:

8.00 moles Mg(ClO3)2 × (2 moles Mg(OH)2 / 2 moles Mg(ClO3)2) = 8.00 moles Mg(OH)2

To convert moles to grams, we need to multiply by the molar mass of Mg(OH)2.

The molar mass of Mg(OH)2 = (24.31 g/mol) + (2 * 16.00 g/mol) = 58.33 g/mol

Grams of Mg(OH)2 = 8.00 moles Mg(OH)2 × 58.33 g/mol = 466.64 g

Therefore, the grams of magnesium hydroxide needed to yield 8.00 moles of magnesium chlorate is approximately 466.64 g.

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The electronic configuration is given as a gray circle is labeled 5 P 6 N. It is surrounded by two concentric circles. The inner circle has gray dots at the north and south positions. Option B

Electron configuration is simply described as the even distribution of electrons in an atom's energy levels, orbitals, and sub orbitals.

It also shows the arrangement of electrons within the electron shells of an atom

The sublevels are written as  (s, p, d, f),

Also, the energy levels, also known as electron shells, are denoted by whole numbers (1, 2, 3, etc)

For Helium with only two electrons, we have;

1s²

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We can see here that the best fuel is the one that produces the most heat per unit mass. In this case, the fuel that produces the most heat per unit mass is methanol.

Fuel is a substance that is used to produce energy through combustion or other chemical reactions. It is commonly utilized to power various forms of transportation, generate heat or electricity, and operate machinery and appliances.

The results of the experiment are shown below:

Fuel            Mass (g)      Heat produced (J)       Heat per gram (J/g)

Methanol 1.0                          350                   350

Ethanol         1.0                          250                   250

Propane         1.0                          200                   200

Butane         1.0                          150                            150

Pentane         1.0                          100                            100

It is important to note that the results of this experiment are only a measure of the heat produced by the fuels.

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The periodic table is arranged in such a way that elements with similar valence electron configurations are placed in the same group or column.

Valence electrons are the outermost electrons in an atom, and they play a critical role in determining the chemical properties of an element.

The elements in each column of the periodic table have the same number of valence electrons, which gives them similar chemical properties

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The number of moles of silver present in a silver spoon that has a mass of 12.86g is 0.12 moles.

The number of moles of a substance can be calculated by dividing the mass of the substance by its molar mass as follows:

The mass of a substance is the quantity of matter which a body contains, irrespective of its bulk or volume.

The mole of a substance is the amount of substance of a system which contains exactly 6.02214076 × 10²³ elementary entities e.g. atoms, molecules.

moles = mass ÷ molar mass

According to this question, silver spoon has a mass of 12.86g. The number of moles can be calculated as follows:

Molar mass of silver (Ag): 107.8682g/mol

moles = 12.86g ÷ 107.8682g/mol

moles = 0.12 moles

Therefore, 0.12 moles of silver are present in the silver spoon.

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Answer:

will be 9.7 Liters

Explanation:

The balanced molecular equation for the reaction between sodium hydroxide (NaOH) and aluminum chloride (\(AlCl_3\)) in aqueous solution can be written as follows: 2NaOH(aq) + 3\(AlCl_3\)(aq) → 3NaCl(aq) + \(Al(OH)_3\)(s)

In this reaction, sodium hydroxide (NaOH) reacts with aluminum chloride (\(AlCl_3\)) to form sodium chloride (NaCl) and aluminum hydroxide (\(Al(OH)_3\)). The coefficients in the balanced equation indicate the stoichiometric ratio between the reactants and products.

The physical states of the substances are indicated by the symbols (aq) for aqueous solutions and (s) for the solid precipitate.

The reaction is a double-displacement reaction, also known as a precipitation reaction. Double-displacement reactions involve the exchange of ions between two compounds, resulting in the formation of a precipitate.

In this case, sodium hydroxide and aluminum chloride react to form sodium chloride and aluminum hydroxide, with aluminum hydroxide being the white solid precipitate.

It's worth noting that the actual reaction might involve hydrated forms of the compounds, such as NaOH·x\(H_2O\) and \(AlCl_3\)·y\(H_2O\). However, for simplicity, these hydrated forms are not included in the balanced equation.

Overall, the balanced equation represents the chemical reaction between sodium hydroxide and aluminum chloride, showing the reactants, products, and their stoichiometric ratios.

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In evolution, isolation means one group is separated and isolated from a population to study the adaption of evolutionary changes over a period of time.

A natural phenomenon called evolution describes how inheritable traits of a species alter through time.

Natural selection, mutation, genetic drift, and migration are the key drivers. Geographical or reproductive isolation stop the exchange of genetic material across populations. As a consequence of adaptation to a particular environment or niche throughout time, populations of many species changed (natural selection).

When there is a barrier that the creatures can't overcome, they become isolated, which implies they are separated from other members of their species. The isolation of organisms is a consequence of environmental change. When mountain ranges or deserts emerge or when continents separate, isolation may develop gradually.

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Tera is 1 trillion

1 trillion has 12 zeros

10^12

While the length is less than a double bond, the strength exceeds that of a double bond.

Due to the presence of two bonds rather than one, triple bonds are stronger than double bonds. An sp-sp sigma bond is created when one of each carbon atom's two sp hybrid orbitals intersects with the corresponding orbital from the other carbon atom.

Six electrons are shared by a sigma bond, two bonds, and a triple bond. Double bonds are more powerful than single bonds, and triple bonds are more powerful than double bonds, according to experiments.

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Answer: third

Explanation:

Answer:

C. Products have higher potential energy, and the reaction is endothermic.

Answer:

0.445 M

Explanation:

Molarity = moles/Volume

M = 9.95/22.35 = 0.445 M

The condensed structure that corresponds to the the lewis structure has a main backbone is 2,2 dichloro butane.

A Lewis structure, also known as a Lewis point formula, Lewis point structure, electron point structure, or Lewis electron point structure, is a diagram showing the bonds between the atoms of a molecule and the lone pairs of electrons present in the molecule.

The Lewis structure is a very simplified representation of the valence shell electrons in a molecule. Used to describe how electrons are arranged around individual atoms in a molecule. Electrons are represented as "dots" or as lines between two atoms to join electrons.

The Lewis structure is based on the concept of the octet rule in which atoms share electrons, so each atom has eight electrons in its outer shell. For example, the oxygen atom has six electrons in its outer shell.

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Answer:

A.) Beaker

B.) Watch Glass

C.) Wire Gauze

D.) Iron Ring

E.) Funnel

F.) Test Tube

G.) Eye Dropper

H.) Pipettes

I.) Tongs

J.) Thermometer

K.) Graduated Cylinder

L.) Ring Stand

M.) Bunsen Lab Burner

N.) Test Tube Holder

O.) Utility Clamp

P.) Water Bottle

Q.) Goggles

R.) Test Tube Rack

S.) Erlenmeyer Flask

T.) Evaporating Dish

U.) Hot Plate

V.) Scoopula/Spatula

The balanced net ionic equation for the reaction that occurs when aqueous solutions of lead(II) nitrate and barium bromide is,

    Pb2+ (aq.)  + 2Br-(aq.) -------------> PbBr2

Lead(II) nitrate, Pb(NO3)2 and barium bromide, BaBr2, are soluble in aqueous solution. This which means that they dissociate completely to form cations and anions when dissolved in water.

Pb(NO2)3 (aq.) + BaBr2(aq.) -----------> PbBr2 (s) + Ba(NO3)2 (aq.)

Balanced net ionic equation for the reaction is the chemical equation that shows only those elements, compounds, and ions that are directly involved in the chemical reaction. Net ionic equations must be balanced by both mass and charge. Balancing by mass means ensuring that there are equal masses of each element on the product and reactant sides. Balancing by charge means making sure that the overall charge is the same on both sides of the equation.

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Answer:

\(12.16\)

Explanation:

We have to start with the reaction between nitric acid and potassium hydroxide:

\(HNO_3~+~KOH~->~H_2O~+~KNO_3\)

With this in mind, we can calculate the number of moles of each compound if we use the molarity equation: \(M=\frac{mol}{L}\) (this means that we have to find the Litters dividing by 1000)

\(95~mL~=~0.095~L\)

\(320~mL~=~0.32~L\)

Now, we can calculate the moles:

\(moles~=~0.2*0.095~=~0.019~mol~HNO3\)

\(moles~=~0.078*0.32~=~0.025~mol~KOH\)

If we have a molar ratio 1:1 (1 mol of \(KOH\) reacts with 1 mol of \(HNO_3\)). So, if we have \(0.019~mol~HNO3\) we will need \(0.019~mol~KOH\). So, we have to calculate the amount of KOH that remains in the solution, so:

\(0.025-0.019~=~0.006~mol~KOH\)

If we have an excess of KOH, this compound will be the cause of the pH value. Therefore we have to calculate the concentration. We already know the moles we have to calculate the volume. The total volume:

\(Vt~=~95mL~+~320mL~=~415~mL~=~0.415~L\)

With this value, we can calculate the concentration of KOH:

\(M=\frac{0.006~mol~KOH}{0.415~L}=0.0145~M\)

We have to keep in mind that this compound is a base, so we have to calculate the pOH value first and then the pH:

\(pOH~=~-Log(0.0145~M)~=~1.84\)

If we remember that: 14 = pH + pOH we can find the pH value:

\(pH~=~14-1.84~=~12.16\)

I hope it helps!

The partial pressure of hydrogen is 0.98 atm while the partial pressure of water is 0.02 atm. The total pressure of the system is 1 atm.

We have seen the reaction as it has been shown in the equation that is attached to the question above. Now, we must have to find the number of moles of the hydrogen that was obtained.

Number of moles of sodium =  1.90 g/23 g/mol = 0.08 moles

2 moles of sodium produces 1 mole of hydrogen

0.08 moles of sodium would produce 0.08 moles * 1 mole/ 2 moles

= 0.04 moles

Given that;

P = pressure

V = volume

n = Number of moles

R = gas constant

T = temperature

PV = nRT

P = nRT/V

P = 0.04 * 0.082 * 298/1

P = 0.98 atm

The partial pressure of the hydrogen = 0.98 atm

The partial pressure of the water = SVP of water at 18°C = 0.02 atm

Total pressure of the system =  0.98 atm +  0.02 atm = 1 atm

The system has a total pressure of 1 atm.

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Answer:

diamond

sugar

rubber

salt (NaCl)

wood

ice

flour

Answer:

diamond

sugar

salt

ice

Explanation:

The purpose of this process is to reduce the risk of having outliers of false results.

It is important to bear in mind that a good scientific experiment usually tests one independent variable at a time, and that is why it is important to keep all other potential variables constant and to use a control group.

Although, the experiment you are referring to in your question is missing the general principle when conducting an experiment is the running of multiple tests before coming up with an actual test result.

Therefore, when completing a science experiment it is important to run multiple tests like heating the substance several times until a constant mass value is obtained,  in other to ascertain the results. the reason why such process is undertaken is to reduce the risk of having outliers of false results.  

A scientific experiment involves several procedures and this depends on the type and purpose of the experiment.

for example ;

An experiment with the purpose of determining how the mass of an object reacts to heat will require the mass of the object to be recorded  after heating the object/substance several times.

Hence we can conclude that the purpose of the process is to reduce the risk of having outliers of false results.

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Explanation:

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Phosphatidylserine is a type of phospholipid that is mainly found in cell membranes. Its structure is made up of two fatty acid chains, a phosphate group, a serine molecule, and a glycerol molecule.

The fatty acid chains are hydrophobic, meaning they repel water, while the phosphate group and serine molecule are hydrophilic, meaning they attract water.

The glycerol molecule acts as a bridge that connects the two fatty acid chains to the phosphate group and serine molecule.
The structure of phosphatidylserine is important for its function in the cell membrane.

Because of the hydrophobic and hydrophilic components of its structure, phosphatidylserine is able to form a lipid bilayer, which is a barrier that separates the inside of the cell from the outside environment.

The hydrophilic heads of the phosphatidylserine molecules face outward and interact with water, while the hydrophobic tails face inward and repel water.
Phosphatidylserine also plays a role in cell signaling and apoptosis, which is programmed cell death.

It acts as a signaling molecule by binding to proteins that are involved in cellular pathways.

In addition, phosphatidylserine is translocated to the outer leaflet of the cell membrane during apoptosis, which signals to immune cells that the cell is ready to be removed.
In conclusion, the structure of phosphatidylserine is made up of two fatty acid chains, a phosphate group, a serine molecule, and a glycerol molecule. Its hydrophobic and hydrophilic components allow it to form a lipid bilayer in cell membranes, and it also plays a role in cell signaling and apoptosis.

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Answer:

4 orbits in the fourth period.

19 electrons in the atom from group 1 and fourth period.

Explanation:

Potassium has 19 electrons distributed in its 4 orbits

The number of periods in a periodic table, tells the number of shells or orbitals of the atoms in that row in which the electrons are filled. Thus the fourth period elements have 4 orbitals and the first element in group one of the fourth period is potassium containing 19 electrons.

All elements in a periodic table are classified into different groups and periods. The vertical columns in the periodic table is called groups and the horizontal rows are called periods.

A group contains elements with same number of valence electrons and similar physical and chemical properties. In a period from left to right the atomic number increases but the number of orbitals in which the electrons are filled will be the same.

Down a group the number of orbitals increases by one. Thus, each elements contains electrons in an increment of 8, 18, 18 and 32 down a group. Thus, from third period to fourth period the number of orbital increases to 4.

The number of electrons will be +8 from the previous element in the group in third period. Thus, below sodium (11) the first element in fourth period is potassium with 19 electrons.

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