How much energy is released when 31.0 g of water freezes? The heat of fusion for water is 6.02 kJ/mol.
Express your answer in kilojoules to three significant figures.

Answer:

The net ionic equation shows the actual reaction more clearly and closer to reality because it writes soluble ionic compounds as the ions and then cancel the spectator ions not involved in the chemical reaction . The net ionic equation results shows the actual chemical reaction taking place.

The net ionic equation for for 2AgF(aq) + k₂S = Ag₂S (s) + 2KF(aq) will be; 2 Ag⁺(aq) + S²⁻(aq) → Ag₂S(s).

To write the net ionic equation for the reaction, we first need to write the balanced molecular equation and then convert it into the ionic equation before finally identifying the net ionic equation.

Write the balanced molecular equation:

2 AgF(aq) + K₂S(aq) → Ag₂S(s) + 2 KF(aq)

In this reaction, silver fluoride (AgF) reacts with potassium sulfide (K₂S) to produce silver sulfide (Ag₂S) and potassium fluoride (KF).

Write the complete ionic equation:

In the complete ionic equation, we separate all the aqueous species (dissociated ions) into their individual ions. Only the solid (s) and gas (g) compounds remain unchanged.

2 Ag⁺(aq) + 2 F⁻(aq) + 2 K⁺(aq) + S²⁻(aq) → Ag₂S(s) + 2 K⁺(aq) + 2 F⁻(aq)

Identify the spectator ions and then write the net ionic equation:

The spectator ions are the ions that do not participate in the actual chemical reaction and remain the same on both sides of the equation. In this reaction, the potassium ions (K⁺) and fluoride ions (F⁻) are spectator ions because they appear on both sides of the equation unchanged.

Net ionic equation:

2 Ag⁺(aq) + S²⁻(aq) → Ag₂S(s)

The net ionic equation shows only the species that actively participate in the chemical reaction. In this case, the silver ions (Ag⁺) and sulfide ions (S²⁻) are the ones involved in forming the silver sulfide (Ag₂S) precipitate.

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--The given question is incomplete, the complete question is

"Write the net ionic equation for this reaction. 2AgF(aq) + k₂S = Ag₂S (s) + 2KF(aq)."--

Answer:

Formic acid

Sodium formiate

Explanation:

To determine acid or base that can generate a buffer solution with pH around 3.5, we have to think in the acid whose pKa = pH.

Although we have to also think in buffer capacity, a measure which can cause a change of 1 pH unit in 1 L of solution.

Buffer capacity does not only depend on the concentration of its components but also of the relationship between that concentrations.

When pH = pKa, buffer capacity is maximum which means that the concentration of conjugated species is the same and the ability to oppose pH changes is maximum.

One example with pH = pKa or nearly if:

COOH⁻  + Na⁺ →  NaCOOH

HCOOH  +  H₂O  →  COOH⁻  + H₃O⁺     Ka: 1.8×10⁻⁴

pKa = 3.74

Answer:

The options are

A) Glycosaminoglycans

B) Gangliosides

C) Peptidoglycans

D) Proteoglycans

E) Selectins

The answer is A) Glycosaminoglycans

Glycosaminoglycans are polysaccharides which comprises of repetitive disaccharides. They are negatively charged as a result of the strong anions present. They are present in some cells of the body and they help in transmission of signals between cells etc.

They also comprise of carboxylate and sulfate groups in its structure.

Answer:

Explanation:

Molecular weight of potassium permanganate is 158 g .

12 g = 12 g / 158 g moles

= .076 moles .

250 mL = .25 L .

Molarity of solution = moles dissolved / volume of solution

= .076 / .25 L

= .304 M .

Molarity of solution is .304 M.  

The molarity of a solution prepared by dissolving 12.0 g of potassium permanganate, KMnO4, in water to make 250.0 mL of solution will be 0.304 M. It can be calculated by using mole formula.

The amount of material in a given volume of the given solution has been measured in molarity (M). The moles of a particular solute per liter of a solution can be known as molarity. The molar solution of known concentration is indeed known as molarity.

A mole is just the quantity of a material that includes exactly 6.022 × [tex]10^{23}[/tex] of the particular chemical elementary entities.

Molecular weight potassium potassium permanganate = 12 g

Volume of the solution = 250mL = 25 L.

Calculation of mole:

Mole can be calculated by using the formula.

Mole = mass / molar mass

Mole = 12 g / 158 g

Mole = 0.076 mole.

Calculation of molarity:

Molarity can be calculated by using the molarity formula:

Molarity = moles of dissolved / volume of solution

Molarity = 0.076 / 0.25

Molarity = 0.304 M

Therefore, the molarity of the solution will be 0.304 M.

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Answer:

the number of protons in a atom is unique to each element

Explanation:

protons are about 99.86% as massive neutrons. The number of protons in a atom is unique to each element .For example carbon atoms have six protons in an atom is referred to as the atomic number of that element

Answer:

Decreases.

Explanation:

The arterial PO2 of a person is decreasing because of carbonmonoxide poisoning due to higher affinity to hemoglobin than oxygen. The PO2 in the blood of arteries are used up by the cells and then there is higher concentration of  carbonmonoxide in the blood as compared to oxygen. Due to this higher amount of carbonmonoxide in the blood, many complications occur such as headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion.

Answer:

4552 mL

Explanation:

From the question given above, the following data were obtained:

Volume of stock solution (V₁) = 55 mL

Molarity of stock solution (M₁) = 12 M

Molarity of diluted solution (M₂) = 0.145 M

Volume of diluted solution (V₂) =?

The volume of the diluted solution can be obtained by using the dilution formula as illustrated below:

M₁V₁ = M₂V₂

12 × 55 = 0.145 × V₂

660 = 0.145 × V₂

Divide both side by 0.145

V₂ = 660 / 0.145

V₂ ≈ 4552 mL

Thus, the volume of the diluted solution is 4552 mL

Answer:

This question is incomplete

Explanation:

This question is incomplete but the completed question is below;

"The following list of properties is most descriptive of a(n) ______

1. High melting point, conductor of electricity when dissolved in water

2. Low melting point, non-conductor of electric current

3. Malleable, ductile, insoluble in water.

The choices for all 3 are: a) metallic solid b) molecular solid c) ionic solid d) all of these e) none of these f) more than one of these"

1. Ionic solid: Ionic solids are solids that have ionic/electrovalent bonds holding it's constituent molecules together. These bonds are strong bonds that involve the transfer of electrons from one constituent atom (the metal) to another constituent atom (the nonmetal). This strong bond causes the solid to have a high melting and boiling point. Also, when dissolved in water, the constituent atoms (involved in the electron transfer) dissociate to form ions (become charged) and thus easily carry electric charges (i.e conduct electricity).

Examples are Sodium Chloride and Potassium Iodide

2. Molecular solids: These are solids whose constituent molecules are held together by a weak bond/force known as Van der Waal forces. This forces are easily broken down when subjected to heat and thus the molecular solids have a low melting point. Also, these solids do not have carriers of heat or electric charges in them and are thus non-conductors of electric current.

Examples are Ice (frozen water) and sucrose

3. Metallic solids: These of solids made from constituent metal atoms only. The nuclei of these constituent metal atoms have the ability to move past one another without disrupting there metallic bonding; it is for this reason they are malleable and ductile. There constituent atoms however do not dissociate in water and are thus insoluble in water.

Examples are aluminium and copper crystal.

Answer:

a. discrete analyzer

b. 96 well microplate

c. flow injection analysis

d. colorimeter

Explanation:

96 well microplates are instruments designed for sample collection and throughput screening. If an environment lab has collected 2000 samples then 96 well microplate is best suited application. Discrete analyzer is automated chemical analyzer which performs test on samples kept in discrete cells. Flow injection analysis is approach used for chemical analysis. It injects a plug of sample into a flowing carrier stream. Colorimeter is a device which measures absorbance of wavelength of light by a specific solution.

Answer:

NON-METAL

Explanation:

Phosphorus is a non-metal that sits just below nitrogen in group 15 of the periodic table. This element exists in several forms, of which white and red are the best known.

Answer: The boiling point of the solution is [tex]101.02^oC[/tex]

Explanation:

We are given:

3.5 % (by weight) NaCl

This means that 3.5 g of NaCl is present in 100 g of solution

Mass of solvent = Mass of solution - Mass of solute

Mass of solvent (water) = (100 - 3.5) g = 96.5 g

Elevation in the boiling point is defined as the difference between the boiling point of the solution and the boiling point of the pure solvent.

The expression for the calculation of elevation in boiling point is:

[tex]\text{Boiling point of solution}-\text{boiling point of pure solvent}=i\times K_b\times m[/tex]

OR

[tex]\text{Boiling point of solution}-\text{Boiling point of pure solvent}=i\times K_f\times \frac{m_{solute}\times 1000}{M_{solute}\times w_{solvent}\text{(in g)}}[/tex] ......(1)

where,

Boiling point of pure solvent (water) = [tex]100^oC[/tex]

Boiling point of solution = ?

i = Vant Hoff factor = 2 (for NaCl)

[tex]K_b[/tex] = Boiling point elevation constant = [tex]0.512^oC/m[/tex]

[tex]m_{solute}[/tex] = Given mass of solute (NaCl) = 3.5 g

[tex]M_{solute}[/tex] = Molar mass of solute (NaCl) = 36.5 g/mol

[tex]w_{solvent}[/tex] = Mass of solvent (water) = 96.5 g

Putting values in equation 1, we get:

[tex]\text{Boiling point of solution}-(100)=2\times 0.512\times \frac{3.5\times 1000}{36.5\times 96.5}\\\\\text{Boiling point of solution}=(1.02+100)^oC\\\\\text{Boiling point of solution}=101.02^oC[/tex]

Hence, the boiling point of the solution is [tex]101.02^oC[/tex]

Answer:

a. True

Explanation:

There is strong inhibition of Carbon Anhydrase by Aceta-zolamide Carbonic Anhydrase. The drug acetazolamide is used as diuretic which increase the urine production in human body. It lowers pressure in eye in glaucoma.

Answer:

a. 599 cm³

b. 1.49 g/cm³

Explanation:

Volume is the amount of space an object occupies. Since this is a brick, the object is a rectangular prism. The formula for the volume of a rectangular prism is the product of length, width, and height.

[tex]V= l *w*h[/tex]

The brick's length (l) is 13.77 centimeters, the width (w) is 8.50 centimeters, and the height (h) is 5.12 centimeters. Substitute these values into the formula.

[tex]V= 13.77 \ cm * 8.50 \ cm * 5.12 \ cm[/tex]

Multiply the numbers together.

[tex]V= 117.045 \ cm^ 2* 5.12 \ cm[/tex]

[tex]V= 599.2704 \ cm^3[/tex]

The original measurements have at least 3 significant figures, so our answer must have 3. For the number we calculated, that is the ones place. The 2 in the tenths place tells us to leave the 9 in the ones place.

[tex]V \approx 599 \ cm^3[/tex]

[tex]\bold {The \ volume \ of \ the \ brick \ is \ approximately \ 599 \ cubic \ centimeters}}[/tex]

Density is the amount of matter in a specified space. The formula for density is mass over volume.

[tex]d= \frac{m}{v}[/tex]

The mass of the brick is 895.3 grams and we just found the volume to be 599.2704 cubic centimeters. Substitute the values into the formula.

[tex]d= \frac{895.3 \ g}{599 \ cm^3}[/tex]

Divide.

[tex]d= 1.494657763 \ g/cm^3[/tex]

Round to three significant figures. For the number we calculated, that is the hundredth place. The 4 in the thousandth place tells us to leave the 9 in the hundredth place.

[tex]d \approx 1.49 \ g/cm^3[/tex]

[tex]\bold {The \ density\ of \ the \ brick \ is \ approximately \ 1.49 \ grams /cubic \ centimeters}}[/tex]

Answer:

1860g.

Explanation:

It is known that the molar mass of C2H6O2 is 62.08 g/mol.,

Now to  solve for the number of moles of solute, one must multiply both

sides by the volume:

moles of solute = (6.00 M)(5.00 L) = 30.0 mol

Notice since the definition of molarity is mol/L, the

product M × L gives mol, a unit of amount.

Use the molar  mass of C3H8O3, one can convert mol to g:

Mass m =30 mol × 62.08 g/mol

m = 1860g.

Hence, there are 1,860 g of C2H6O2 in the specified amount of

engine coolant.

Explanation:

since there are no lone pairs on the central atom, the shape will be tetrahedral

Answer:

1569 torr

Explanation:

Assuming ideal behaviour and constant temperature, we can solve this problem by using Boyle's law, which states:

Where in this case:

We input the data given by the problem:

And solve for P₂:

Answer:

c9h8o2

Explanation:

The molecule which has 9 carbon atom is [tex]C_{9} H_{8} O[/tex](cinnamaldehyde).

 More than one atoms make up a molecule. If they have more than one atom, atoms could be the same for example, an oxygen molecule contains two oxygen atoms) as well as different (for example, a hydrogen molecule contains two hydrogen atoms.

Cinnamaldehyde is a kind of organic chemical with the formula C6H5CH=CHCHO and the formula C6H5CH=CHCHO. It's mostly the trans isomer that's found in nature.

It is known that the number of carbon atom is 9 hence molecule will be cinnamaldehyde

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TRUE

Explanation:

*not sure about this answer

Answer:

welcome to mobile legends

Explanation:

ml ka muna maya kana mag module

Answer:

Temperature affects the kinetic energy in a gas the most, followed by a comparable liquid, and then a comparable solid. The higher the temperature, the higher the average kinetic energy, but the magnitude of this difference depends on the amount of motion intrinsically present within these phases.

Explanation:

Liquids have more kinetic energy than solids. When a substance increases in temperature, heat is being added, and its particles are gaining kinetic energy. Because of their close proximity to one another, liquid and solid particles experience intermolecular forces. These forces keep particles close together.

Answer:

where are the muscle tissues

Answer:

e−(Ea/RT): the fraction of the molecules present in a gas which have energies equal to or in excess of activation energy at a particular temperature

Answer:

The volume will be 185.83 mL.

Explanation:

Gay-Lussac's law indicates that when there is a constant volume, as the temperature increases, the pressure of the gas increases. And when the temperature is decreased, the pressure of the gas decreases. Gay-Lussac's law can be expressed mathematically as follows:

[tex]\frac{P}{T} =k[/tex]

Where P = pressure, T = temperature, k = Constant

Boyle's law says that the volume occupied by a given gaseous mass at constant temperature is inversely proportional to pressure. Boyle's law is expressed mathematically as:

P*V=k

Where P = pressure, V = volume, k = Constant

Finally, Charles's Law consists of the relationship that exists between the volume and the temperature of a certain quantity of ideal gas, which is kept at a constant pressure. For a given sum of gas at a constant pressure, as the temperature increases, the volume of the gas increases and as the temperature decreases, the volume of the gas decreases because the temperature is directly related to the energy of the movement of the gas molecules. .

In summary, Charles's law is a law that says that when the amount of gas and pressure are kept constant, the quotient that exists between the volume and the temperature will always have the same value:

[tex]\frac{V}{T} =k[/tex]

Combined law equation is the combination of three gas laws called Boyle's, Charlie's and Gay-Lusac's law:

[tex]\frac{P*V}{T} =k[/tex]

Studying two different states, an initial state 1 and a final state 2, it is satisfied:

[tex]\frac{P1*V1}{T1} =\frac{P2*V2}{T2}[/tex]

In this case:

Replacing:

[tex]\frac{720 torr*256 mL}{308 K} =\frac{950 torr*V2}{295 K}[/tex]

Solving:

[tex]V2= \frac{295K}{950 torr} *\frac{720 torr*256 mL}{308 K}[/tex]

V2= 185.83 mL

The volume will be 185.83 mL.

Answer:

a. 0.7119 g

Explanation:

To solve this question we need to know that all carbon of the compound will react producing CO2 and all Hydrogen producing H2O.

Thus, we can find the mass of C and the mass of H and by difference regard to the 2.584g of the compound we can find the mass of oxygen as follows:

Moles CO2 = Moles C -Molar mass: 44.01g/mol-

5.874g CO2 * (1mol/44.01g) = 0.1335 moles CO2 = 0.1335 moles C

Mass C -Molar mass: 12.01g/mol-:

0.1335 moles C * (12.01g /mol) = 1.6030g C

Moles H2O -Molar mass: 18.01g/mol-

2.404gH2O * (1mol / 18.01g) = 0.1335 moles H2O * (2mol H / 1mol H2O) = 0.267 moles H

Mass H -Molar mass: 1g/mol-

0.267 moles H * (1g/mol) = 0.2670g H

Mass Oxygen =

Mass O = 2.584g compound - 1.6030g C - 0.2670g H

Mass O = 0.714g O ≈

Answer:

2 H₂O(l) + 2 e⁻ ⇒ H₂(g) + 2 OH⁻(aq)

Explanation:

Let's consider the unbalanced half-reaction for the reduction of liquid water to gaseous hydrogen in basic aqueous solution.

H₂O(l) ⇒ H₂(g)

First, we will perform the mass balance. We will balance oxygen atoms by multiplying H₂O by 2 and adding 2 OH⁻ to the right side.

2 H₂O(l) ⇒ H₂(g) + 2 OH⁻(aq)

Then, we perform the charge balance by adding 2 electrons to the left side.

2 H₂O(l) + 2 e⁻ ⇒ H₂(g) + 2 OH⁻(aq)

Answer:

[tex]V_{O2}= 1.5m^3[/tex]

Explanation:

From the question we are told that:

Volume of H_2O consumed [tex]V_{H2O}=3.0cm^3[/tex]

Balanced equation of Reaction is

[tex]2 F_2 + 2 H_2O -> 4 HF + O_2[/tex]

Therefore

O_2 produced in Volume is

 [tex]V_{O2}= \frac{1}{2}*V_{H2O}[/tex]

 [tex]V_{O2}= \frac{1}{2}*3.0m^3[/tex]

 [tex]V_{O2}= 1.5m^3[/tex]

Answer:

Mass=Moles × RFM

Mass= 0.28M× 164

Mass= 45.92 grammes

Answer:

Explanation:

The electron affinity (EA) of an element is the energy change that occurs ... Atoms with the largest radii, which have the lowest ionization energies (affinity for their own valence electrons), also have the ... Based on their positions in the periodic table, which of Rb, Sr, or Xe would you