How can you determine if a chemical change has occured

Answer:

B. (Linear graph with positive slope)

Explanation:

The picture above showing that  

1. T2 is higher than T1

2. V2 is higher than V2

From this, we can conclude that the relationship for temperature (T) and volume(V) is positive. That means a higher temperature will result in a higher volume.  

Since the relationship positive, the graph will have a positive slope. We can't prove if the graph should be linear or exponential since we don't have the exact number of the experiment.

Answer:

B.

Explanation:

Answer: m= 1.02x10² g AlCl3 or 1091.3 g AlCl3

Explanation: solution attached.

Convert mass of Mg to moles

Do the mole ratio between Mg and AlCl3 based from the balanced equation.

Convert moles of AlCl3 to mass using its molar mass.

Answer: Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus. 

so C would seems to be right.

Explanation: The energy of an electron depends on the size of the orbit and is lower for smaller orbits. Radiation can occur only when the electron jumps from one orbit to another. The atom will be completely stable in the state with the smallest orbit, since there is no orbit of lower energy into which the electron can jump.

Answer:

d

Explanation:

Just did it on edge

The wavelength of the light emitted is 5 x [tex]10^{-3}[/tex] nm

Explanation:

The wavelength of light from an LED with a frequency of 60 Hz is not in the visible spectrum and would be extremely long, measuring 5 x 10^15 nm, which falls within the range of radio waves.

To determine the wavelength of light emitted by an LED lightbulb with a frequency of 60 Hz, we must use the relationship between the speed of light, frequency, and wavelength. The equation we use is c = λν, where c is the speed of light in vacuum (approximately 3 × 108 m/s), λ is the wavelength, and ν is the frequency. However, a frequency of 60 Hz would result in a wave that is not within the visible light spectrum but rather in the range of radio waves, and its wavelength would be extremely long compared to visible light wavelengths measured in nanometers.

To calculate the wavelength in meters, we divide the speed of light by the frequency:

λ = c / ν

λ = (3 × 108 m/s) / (60 Hz)

λ = 5 × 106 m

To convert this to nanometers (nm), knowing that 1 m = 109 nm, we multiply by 109:

λ = 5 × 106 m × 109 nm/m

λ = 5 × 1015 nm

This wavelength is much larger than the wavelengths for light in the visible spectrum, which are typically between 380 nm and 750 nm. Consequently, the wavelength of 60 Hz frequency light cannot be represented in nanometers as it falls outside the visible range.

Final answer:

DNA is packaged into a structure called a chromosome inside cells. In prokaryotes, supercoiling helps in this process, while in eukaryotes, DNA wraps around histone proteins to form nucleosomes and further condenses into chromatin fibers, ultimately forming chromosomes.

Explanation:

When the DNA molecule folds, coils, and supercoils to fit inside a cell, it forms a structure known as a chromosome. In prokaryotic cells, like E. coli, DNA supercoiling helps to fit the large DNA molecule into a very small space. In eukaryotic cells, the process is more complex, involving the winding of DNA around histone proteins to form nucleosomes, which look like 'beads on a string.' These nucleosomes further coil into a 30-nm chromatin fiber. During cell division, the chromatin fibers condense even further to form the tightly-packed chromosomes visible under a microscope.

The degree of DNA supercoiling can vary, resulting in DNA that is either under-wound or over-wound. Proteins like topoisomerases are involved in maintaining the supercoiled structure of chromosomes, which is crucial for efficient DNA replication and transcription. This intricate packaging allows DNA, which can be up to 2 meters long in humans, to fit within the tiny nucleus of a cell.

The number of protons in an isotope of an element is determined by its atomic number. The element Chromium (Cr) has an atomic number of 24, so all its isotopes, including Cr-50, Cr-52, Cr-53, and Cr-54, contain 24 protons.

The element symbol Cr represents the element Chromium. The number of protons in any isotope of an element is determined by the atomic number, not the isotope number. Chromium has an atomic number of 24, so all isotopes of Chromium, including Cr-50, Cr-52, Cr-53, and Cr-54, contain 24 protons.

The number of protons in an isotope of an element is determined by its atomic number. The element Chromium (Cr) has an atomic number of 24, so all its isotopes, including Cr-50, Cr-52, Cr-53, and Cr-54, contain 24 protons.

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Answer:

             The structure of Ethambutol is attached below. As it can be seen in structure that there are three different atoms which can act as a central atom and hence, can make a geometrical shape. These three atoms are;

(i) Carbon (Tetrahedral):

                Each carbon atom in this compound is Sp³ hybridized because there is no double or triple bond in this compound. So, according to VSEPR theory the four bonded atoms will keep a maximum distance from each other to experience less repulsion. Therefore, the bond angle about carbon atom will be 109.5° and the shape will be Tetrahedral.

(ii) Nitrogen (Trigonal Pyramidal):

                 There are two atoms of Nitrogen in this compound. These Nitrogen atoms are bonded to three atoms. Also, it has one lone pair of electron. This pair of electron will cause the the bond between the atoms to decrease due to more repulsion hence making the bond angle less than 109.5° and giving a Trigonal Pyramidal shape.

(iii) Oxygen (Bent / Angular):

                 The two oxygen atoms are bonded to two atoms and contain two lone pair of electrons, hence, more repulsion and more small angle i.e. 104° giving a bent or angular shape.

Ethyne is prepared by using water and calcium carbide in the laboratory.

Explanation:

Acetylene is conveniently prepared in the laboratory by the action of water(H₂O) on calcium carbide (CaC₂). Calcium carbide in turn is obtained by heating the mixture of coke and lime stone in an electric furnace.

CaC₂ + 2H₂O → Ca(OH)₂ + C₂H₂

Ethyne gas prepared in the lab using the above method may contain impurities like H₂S, PH₃, AsH₃, NH₃etc. The gas is purified by bubbling it through acidified copper sulfate solution.

Answer:

mol H2S = 1.28 mol

Explanation:

balanced reaction:

∴ moles HCl = 2.56 mol

⇒ moles H2S = ?

⇒ moles H2S = (2.56 mol HCl)*(mol H2S/2 moles HCl)

⇒ moles H2S = 1.28 mol

Explanation:

This given reaction is a chemical reaction that is : Double decomposition reaction .

In this reaction , there is a reaction between two compounds in which they mutually interchange their ions .

That is :

AB +CD ---> AC +BD

Similarly in this we have :

Na3PO4+KOH—->NaOH + K3PO4

The double decomposition reaction is either :

Precipitation reaction : resulst in the formation of ppt .

Neutralization reaction : results in the formation of neutral substance

Answer:

Water

Explanation:

one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. Water is a tasteless, odorless liquid at ambient temperature and pressure. Which is known to be crystal blue.

Answer:

well I t could be in liquid form or in air form

Explanation:

Answer:

density

Explanation:

There are, mainly, three states of matter (solid, liquid and gas). These can be defined differently from the other according to their physical properties. In order to do this, scientists use the word "density" to compare their properties.

Solid has a higher density compared to liquid and gas. This is because its particles are tightly packed. Liquid has a lower density when compared to solid because its particles are loosely arranged. Gas has the lowest density among the three. This means that the gas particles have a very big space, thus rising to a higher kinetic energy.

Thus, this explains the answer.

Answer:

It stays àt 80j

Explanation:

The total energy of the isolated system remains 80 J as the gravitational potential energy is converted into kinetic energy in a frictionless environment, maintaining conservation of energy.

As the box slides down the frictionless slide, the total energy of the system remains constant due to the conservation of energy principle. The initial 80 J of gravitational potential energy is progressively converted into kinetic energy as the box moves down the slide. Since the slide is frictionless, there are no dissipative forces like friction to convert mechanical energy into heat. Hence, the isolated system, which includes the box, slide, and earth, will still store 80 J of total energy, but in different forms (mostly kinetic energy when the box is at the bottom of the slide).

The human use of coal impacts air and water quality significantly. The burning of coal results in air pollution, contributing to global health and environmental issues. Additionally, processes related to coal use also contaminate local water bodies, damaging aquatic ecosystems and affecting the safety of drinking water.

The human use of coal has significant impacts on both air and water quality. When coal is burned for energy, it releases pollutants, including sulfur dioxide and nitrogen oxides into the atmosphere. These substances can lead to air pollution, contributing to issues like acid rain, smog, respiratory diseases, and global warming.

Coal mining and combustion also affect water quality. Acid mine drainage, where water in coal mines becomes acidic and leaks out, can contaminate local water bodies, harming aquatic life and making the water unsafe for human consumption. Moreover, coal-fired power plants often discharge waste materials containing heavy metals like mercury into water bodies, further deteriorating water quality.

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Answer: 2 NH3 => 2 N + 3 H2

Explanation: The equation is now balanced.

2 atoms of N in both the reactant and product side and 6 atoms for H on both sides.

"An advertisement for a commercial hand warmer claims that the hand warmer works because a chemical reaction in the hand warmer draws out the body’s own natural heat causing a warming effect"

Explanation:

Hand warmer

        A) Crystalline type

        B) Air activated

        C) Lighter

        D) Battery

        E) Charcoal

Answer:

false

Explanation:

Answer:

Lead (/ˈlɛd/) is a chemical element with the symbol Pb

Answer:

12.371

Explanation:

pH of a 0.0235 M HCl solution is;

pH = -log[H+ ] = -log(0.0235) = 1.629

pOH = 14.000 – pH = 14.000 – 1.629 = 12.371

Taking into account the definition of pH and pOH, the pOH of a 0.0235 M HCl solution is 12.37.

In first place, pH is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance. Mathematically, pH is expressed as the negative base 10 logarithm of the hydrogen ion concentration:

pH= - log [H⁺]= -log [H₃O⁺]

A strong acid is an acid that ionizes almost completely in aqueous solution, so the concentration of protons equals the concentration of the acid.

Being HCl a strong acid, then

[HCl]= [H⁺]= [H₂O⁺]= 0.0235 M

Then, the pH of the solution is:

pH= -log (0.0235 M)

pH= 1.63

On the other hand, pOH is a measure of the concentration of hydroxyl ions in a solution. The following relationship can be established between pH and pOH:

pH+ pOH= 14

In this case:

1.63 + pOH= 14

Solving:

pOH= 14 - 1.63

pOH= 12.37

Finally, the pOH of a 0.0235 M HCl solution is 12.37.

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The mass of 187 liters of CO2 gas is 0.36 g.

Explanation:

The molecular weight of CO2 is 44 g / mol.

1 kg of CO2 = 1000 g [tex]\times[/tex] ( 1 mole / 44 g) = 22.7 mole of CO2.

By using the ideal gas equation,

                                    PV = nRT

                                      V = nRT / P

where P represents the pressure,

          V represents the volume,

          T represents the temperature,

          R represents the ideal gas constant,

          n represents the amount of substance.

                                   V = (22.7)[tex]\times[/tex](0.0821)[tex]\times[/tex](273.15) / 1

                                   V = 509.6 L of CO2 at STP

            Mass = (187 L of CO2 gas) / (509.6 L of CO2 at STP)

                       = 187 / 509.6

            mass = 0.36 g

To find the mass of 187 liters of CO2 gas at STP, we calculate the number of moles using the molar volume of 22.4 L/mol and then multiply by the molar mass of CO2 (44.01 g/mol) to get a mass of approximately 367.34 grams.

The mass of 187 liters of CO2 gas at STP (standard temperature and pressure) can be calculated by first determining the number of moles of CO2. The molar volume of an ideal gas at STP is 22.4 liters, so by dividing the volume of the gas by the molar volume, we can get the numbers of moles.

Here's the calculation:

Number of moles of CO2 = Volume of CO2 / Molar Volume at STP = 187 L / 22.4 L mol-1

Number of moles = 8.348 moles (rounded to three decimal places)

The molar mass of CO2 is 44.01 g/mol, so now we can calculate the mass:

Mass of CO2 = Number of moles×  Molar Mass = 8.348 moles ×44.01 g/mol

Mass = 367.34 g (rounded to two decimal places)

The mass of 187 liters of CO2 gas at STP is approximately 367.34 grams.

The increase in pressure will result in the decrease of the total number of gas molecules due to the shift in equilibrium toward the side with fewer moles of gas, following Le Châtelier's principle.

According to Le Châtelier's principle, how will a pressure increase affect a system that includes matter in the gas phase and another phase? The correct answer is D. The total number of gas molecules will decrease. This is because Le Châtelier's principle states that a pressure increase will shift an equilibrium toward the side of the reaction with the fewer number of moles of gas, as this helps to counteract the change by reducing the pressure within the system. This principle is particularly useful when predicting how a change in pressure will affect the position of equilibrium in a chemical reaction involving gases.

Final answer:

Le Châtelier's principle indicates that increased pressure in a gaseous reaction shifts equilibrium toward the side with fewer gas molecules to reduce the stress caused by the pressure increase.

Explanation:

According to Le Châtelier's principle, a pressure increase in a system involving gases will cause a shift in equilibrium towards the phase with the fewer number of gas molecules. In the case of a reaction with different numbers of gas molecules on each side of the reaction, such as 2NO(g) + O₂(g) ⇒ 2NO₂(g), an increase in pressure would shift the equilibrium towards the formation of NO₂, since it has fewer gas molecules (2) compared to the reactants (3). This phenomenon occurs because the system responds to reduce the pressure by favoring the production of fewer molecules that would occupy less volume.

Answer:

                     D) There are fewer grams of HCl than Mg(OH)₂

Explanation:

                    The balance chemical equation for given reaction is as;

                        Mg(OH)₂ + 2 HCl → MgCl₂ + 2 H₂O

Step 1: Calculate Moles of Mg(OH)₂ and HCl as;

Mg(OH)₂:

              Moles  =  Mass / M.Mass

              Moles  =  25.3 g / 58.319 g/mol

              Moles  =  0.433 moles of Mg(OH)₂

HCl:

              Moles  =  Mass / M.Mass

              Moles  =  22.5 g / 36.460 g/mol

              Moles  =  0.617 moles of HCl

Step 2: Find out Limiting reagent as;

According to equation,

                   1 mole of Mg(OH)₂ reacted with  =  2 moles of HCl

So,

             0.433 moles of Mg(OH)₂ will react with  =  X moles of HCl

Solving for X,

                     X  =  0.433 mol × 2 mol / 1 mol

                    X =  0.866 moles of HCl

This means for given amount of Mg(OH)₂ we require 0.866 moles of Hcl while, we are only provided with 0.617 moles of HCl hence, HCl is the limiting reagent and will control the final yields of products.

Step 3: Find out Moles of MgCl₂ produced;

According to equation,

                   2 moles of HCl produced  =  1 mole of MgCl₂

So,

             0.617 moles of HCl will produce  =  X moles of MgCl₂

Solving for X,

                     X  =  0.617 mol × 1 mol / 2 mol

                    X =  0.3085 moles of MgCl₂

Step 4: Calculate Mass of MgCl₂ as;

                   Mass  =  Moles × M.Mass

                   Mass  =  0.3085 mol × 36.46 g/mol

                   Mass =  11.24 g of MgCl₂

Answer:

A) The amounts of both reactants are given.

Explanation:

The amounts of both reactants are given. You cannot tell which reactant will be used up first. Calculate the mass of product that can be produced from the amount of the first reactant; calculate the mass of product that can be produced from the second reactant. Compare the two. The limiting reactant produces the least product.

The same volume, pressure, and temperature. Option C

Equal volumes of gases at equal temperatures and pressures contain an equal number of molecules, according to Avogadro's principle. Thus, it can be presumed that two gas samples have the same volume, pressure, and temperature if they contain the same number of molecules and no information about changes in circumstances is given.

The relationship between pressure (P), volume (V), and temperature (T) for a given amount of gas (n) is described by the ideal gas law, which is compatible with this.

Answer:

1.0511458x10^22

Explanation:

0.633 mol/ 1 x 6.022x10^23/1 mol

Answer:

pumice and gneiss

Explanation:

both are formed by conduction of energy

Explanation:

Combination reaction

It is a reaction in which some substances or reactants combine to form a single substance or we can all it as single product .

Like : A + B --> C+D

This combination can be between a element and a element like :

H₂ +O₂--> H₂O

It can be between element and a compound like :

SO₂ + O₂---> SO₃

It can be between a compound and a compound like :

H₂O + CO₂---> H₂CO₃

In the above asked question , the combination is between Cu and a sulphur that is element and a element that is :

Cu + S ---> CuS

                 (copper sulphide )

Answer:

MgCl2

Explanation:

Lattice energy will be higher on ion with higher charge, or smaller size. A higher charge means it will have a stronger force. Smaller size ion will have less distance.  

Magnesium has +2 charge and located in the third row, make it strongest of these three. Natrium will be the second strongest even though its charge is +1, the same as Kalium. Natrium has smaller size as it is on the third row, compared to Kalium that was in the fourth row.

MgCl2 would have the most negative lattice energy due to the higher charge of Mg²⁺ and its smaller ionic radius.

Lattice energy refers to the energy required to separate one mole of an ionic compound into its gaseous ions. It is determined by the charges and sizes of the ions involved. The more negative the lattice energy, the stronger the ionic bond.

The most negative lattice energy among NaCl, KCl, and MgCl2 is found in MgCl2. This is due to the higher charge of Mg²⁺ compared to Na⁺ and K⁺, as well as its smaller ionic radius. These factors result in stronger electrostatic attractions between the ions, leading to a more negative lattice energy.

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Answer:

n=N/Na

----. N=nxNa=3x6.023x10^23=1.8069e+24

Answer:

Square root { 2g * Delta-y * /m}

Explanation:

it is as shown in the attached file.

Note that the expression "2gΔy" with the square root can be represented as: [tex]\[2g\sqrt{\Delta y}\][/tex]

The expression [tex]\[2g\sqrt{\Delta y}\][/tex] represents a mathematical formula involving the square root of the change [tex](\Delta)[/tex] in the variable y. Here:

- 2 is a constant multiplier,

- g is a constant (possibly representing the acceleration due to gravity),

-  [tex]\sqrt{\Delta y}[/tex] denotes the square root of the change in y.

It is a concise way to express a quantity that involves a constant, the square root, and a change in a variable. The specific interpretation would depend on the context of the problem or equation in which it appears.

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Answer: 3.25x10²⁴ atoms Zn

Explanation: Convert moles of Zn to atoms using Avogadro's number

5.4 moles Zn x 6.022x10²³ atoms Zn/ 1 mole Zn

= 3.25x10²⁴ atoms Zn

Answer:

                    49.52 g of H₂O

Explanation:

                    The balance chemical equation for given reaction is as follow;

                                  4 HCl + O₂ → 2 H₂O + 2 Cl₂

Step 1: Find out Limiting reagent as;

According to balance equation,

                    4 moles of HCl reacted with  =  1 mole of O₂

So,

                5.50 moles of HCl will react with  =  X moles of O₂

Solving for X,

                     X =  5.50 mol × 1 mol / 4 mol

                     X =  1.375 moles of O₂

This means to completely consume 5.5 moles of HCl we will need 1.375 moles of O₂ while, we are provided with 3.0 moles of O₂ which is in excess hence, the limiting reagent in this problem is HCl and it will control the yield of products.

Step 2: Calculate Moles of H₂O produced;

According to balance equation,

                    4 moles of HCl produced  =  2 moles of H₂O

So,

                5.50 moles of HCl will react with  =  X moles of H₂O

Solving for X,

                     X =  5.50 mol × 2 mol / 4 mol

                     X =  2.75 moles of H₂O

Step 3: Calculate Mass of H₂O as;

                Mass  =  Moles × M.Mass

                Mass  =  2.75 mol × 18.01 g/mol

                Mass =  49.52 g of H₂O