How could you tell if a substance has undergone a physical change or a chemical one?

Answers

Answer 1

Answer: Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions.

A physical change is are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds.


Related Questions

1 ton of methanol are accidentally discharged into a lake. By how much is the biological oxygen demand of this water increased

Answers

The biological Oxygen demand of the lake is increased by 1.5 ton.

Discussion:

The reaction of methanol with Oxygen is as follows;

2CH3OH + 3O2 ==> 2CO2 + 4H2O.

In the reaction above; Since Methanol, CH3OH and Oxygen, O2 have the same molar mass; 32.

Therefore we can say since;

2 moles of CH3OH requires 3 moles of O2.

Therefore, 1 ton of methanol will require 1.5 ton of oxygen.

The biological Oxygen demand of the water is therefore increased by 1.5 ton as this is the amount of Oxygen consumed by the ethanol.

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the bleaching action of sulphur (iv) oxide is by​

Answers

Answer:

The bleaching action of sulphur di oxide is temporary because it involves the process of reduction. sulphur di oxide removes oxygen from the coloured substance and makes it colourless. Atmospheric oxygen slowly takes place of the removed oxygen and because of which the material regains the co

The mass of a metal ball was 20.350 g. The volume of the water in a 25 mL graduated cylinder was increased from 16.05 to 17.90 mL when the metal ball was placed in the cylinder. What is the density of the metal ball

Answers

Answer:

11000 g/L

Explanation:

Since density is mass divided by volume, find the volume of the metal ball by subtracting the initial volume of water in the graduated cylinder from the ending volume. In this case, the volume would be 17.90 mL - 16.05 mL =  1.85 mL = 0.00185 L. Then using the formula for density, calculate 20.350 g / 0.00185 L = 11000 g/L.

Density is an intensive property as it does not depend on the quantity of the substances Whereas mass and volume are extensive property. Therefore, the density of the metal ball is 11000 g/L.

What is density?

Density tells about the compactness of the substances, how much dense is the substances in other words. Object that is more denser than water they just sink in the water.

Mathematically,

Density = Mass of the metal ball ÷volume marked on the graduated cylinder

volume=ending volume- initial volume of water in the graduated cylinder            

            =17.90 mL - 16.05 mL

            =  1.85 mL

            = 0.00185 L.

substituting all the given values in the above equation, we get

density=  20.350 g / 0.00185 L

            = 11000 g/L.

Therefore, the density of the metal ball is 11000 g/L.

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Electromagnetic waves travel fastest through
A -Solid
B -Liquid
C -Gas
D-Vacuum

Answers

Answer:

Gas

Explanation:

Mechanical waves- travel faster in solids & slowest in gases

Electromagnetic waves- travel fastest in empty space and slowest in solids.

Because they are so close, than can collide very quickly, i.e. it takes less time for a molecule of the solid to 'bump' into its neighborough. Solids are packed together tighter than liquids and gases, hence sound travels fastest in solids. The distances in liquids are shorter than in gases, but longer than in solids.

Answer C- Gas

Explanation:

Electromagnetic waves- travel fastest in empty space and slowest in solids.

A 15.0-L vessel contains 0.50 mol CH4 with a pressure of 1.0 atm. After 0.50 mol C2H6 is added to the vessel, what is the partial pressure of CH4? The temperature remains unchanged throughout the process.

Answers

Answer: Hi! The partial pressure of CH4 is

=1 atm

Explanation:

The partial pressure of methane in the mixture of methane and ethane has been 1 atm.

Partial pressure has been the pressure exerted by a gas in the solution or mixture. The partial pressure of each gas has been the total pressure of the gaseous mixture.

The partial pressure of the gas has been dependent on the volume, temperature, and concentration of the gas.

The given methane has a partial pressure of 1 atm in the 15 L vessel. The addition of ethane results in the change in the total pressure of the mixture, as there have been additional moles of solute that contributes to the solution pressure.

However, since there has been no change in the concentration and volume of methane, the pressure exerted by methane has been the same. Thus, the partial pressure of methane has been 1 atm.

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Can KI+Cl2 occur or not

Answers

Yes according to reliable sources.

Explain why caesium is more reactive than sodium.
You should answer in terms of electrons.

Answers

Caesium is more reactive than sodium because when it is burned sodium will smell, taste, and look like poop

cyclopropane is a commonly used anesthetic. If a 2.00 L flask contains 3.11 g of cyclopropane gas at 684 mmHg pressure and 23.0 C, what is the molecular mass of cyclopropane

Answers

Answer:

42.0g/mol

Explanation:

The steps for this question is to use the ideal gas law, and then use n=m/M to find molar mass.

PV = nRT

n= PV/RT

Change 23 degrees to 296.15 K and 684mmHg to kpa

n = (91.1925kpa)(2.00L)/(8.314Lkpa/mol K)(296.15K)

n= 0.074mol

n = m/M

M = m/n

M = 41.98489g/mol

A gas has a pressure of 8.5atm and occupies 24L at 25∘C. What volume (in liters) will the gas occupy if the pressure is increased to 13.5atm and the temperature is decreased to 15∘C? Round to the nearest liter.

Answers

The volume (in liters) that the gas will occupy if the pressure is increased to 13.5 atm and the temperature is decreased to 15 °C is 15 L

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

Initial pressure (P₁) = 8.5 atm

Initial volume (V₁) = 24 L

Initial temperature (T₁) = 25 °C = 25 + 273 = 298 K

Final pressure (P₂) = 13.5 atm

Final temperature (T₂) = 15 °C = 15 + 273 = 288 K

Final volume (V₂) =?

The final volume of the gas can be obtained by using the combined gas equation as illustrated below:

[tex]\frac{P_{1}V_{1}}{T_{1}} = \frac{P_{2}V_{2}}{T_{2}}\\\\\frac{8.5 * 24}{298} = \frac{13.5 * V_{2}}{288}\\\\ \frac{204}{298} = \frac{13.5 * V_{2}}{288}\\\\[/tex]

Cross multiply

298 × 13.5 × V₂ = 204 × 288

4023 × V₂ = 58752

Divide both side by 4023

[tex]V_{2} = \frac{58752}{4023}\\\\[/tex]

V₂ = 15 L

Therefore, the final volume of the gas is 15 L

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Your skin is an important organ and has several functions. All of the functions below are performed by the skin EXCEPT
A)
makes vitamin D.
B
prevents-dehydration:
C)
maintains body temperature.
D)
works with bones to help you move

Answers

Answer:

D. works with bones to help you move

Explanation:

Your muscles and tendons are what help bones move.

No one helps me please find an answer to my recent question in chemistry...please!!!​

Answers

oh so sad for ur msg

if i were science student then absolutely i will help

but i am। computer science student in management faculty so so sry

Explanation:

your answer to the chemistry question is given !

hope that helps you.

What is the use of GMO?

Answers

Some benefits of genetic engineering in agriculture are increased crop yields, reduced costs for food or drug production, reduced need for pesticides, enhanced nutrient composition and food quality, resistance to pests and disease, greater food security, and medical benefits to the world's growing population.

Insect resistance: Corn

Herbicide tolerance: Soybean

HELP ME OUT PLEASE!!

Barium sulfate, BaSO4 is a white crystalline solid that is insoluble in water. It is used by doctors to diagnose problems with the digestive system,

Barium hydroxide, Ba(OH)2 is also a white crystalline solid and is used in wastewater treatment.

How many more oxygen atoms are represented in the formula for barium sulfate than in the formula for barium hydroxide?

A) 2

B) 4

C) 1

D) 8​​

Answers

Answer: 2

Explanation:

Ba(OH)2 contains two oxygen atoms

BaSO4 contains four oxygen atoms.

This means that barium sulfate contains two more oxygen atoms than barium hydroxide in its formula.

Hope this helps!! :)

According to formula BaSO₄, Barium sulfate contains 2 more oxygen atom.

The correct option is (A) 2

Barium sulfate's distinguishing feature

Ba(OH)₂ has two oxygen atoms in it.

Four oxygen atoms may be found in BaSO₄.

This indicates that the formula of barium sulfate has two extra oxygen atoms than the formula of barium hydroxide.

Barium sulfate, often known as BaSO4, is a transparent white pigment that has a long history. It is produced by combining sulfuric acid with barium hydroxide and other sources of barium.

Chemically speaking, barium hydroxide has the formula Ba(OH)2. The monohydrate of barium, sometimes referred to as baryta or baryta-water, is one of the element's main compounds. The typical commercial form of monohydrate is this white granular substance.

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Which statement best describes mechanical energy?

A.the energy of heat and magnetism

B.the energy of electricity and motion

C.the energy of moving parts and motion


D.the energy of electricity and heat

Answers

Answer:

the answer is B.

Explanation:

your welcome

Answer:

the answer is B

Explanation:

i have the same exact questionn

A 5.35 M sugar solution is diluted from 240.0 mL to 862.5 mL. What is the concentration of the dilute solution

Answers

Answer:

1.345.0

Explanation:

Hope this helpssss

which mass movement does this describe?

Answers

Answer:

landslide mudflows slump and creep

Explanation:

no explanation

Select the container from the figure (Figure 1) that represents the dilution of a 4 % (m/v) KCl solution to each of the following: Figure1 of 1 There is a diagram showing several containers. One container is filled with 4 percent of mass to volume solution of NaCl. Container 1 is filled with a solution in which volume is two times less than the volume of NaCl solution. Container 2 is filled with a solution of a volume two times larger compared to the NaCl solution. Container 3 is filled with a solution of a volume two times larger than the volume of the solution in container 2. Part A 2 % (m/v) KCl

Answers

From the dilution formula, we have that at constant value of the solute, the volume of the solution is inversely proportional to the concentration.

The correct responses are;

Part A: Container 2Part B: Container 3

Reasons:

The given parameters are;

The concentration of the KCl solution = 4% m/v

Taking the solution as solution of KCl

The volume of the solution in container 1 = Two times less than the volume of KCl solution.

[tex]V_{container \, 1} = \displaystyle \mathbf{ \frac{1}{2} \cdot V_{4\% \, solution}}[/tex]

The volume of the solution in container 2 = Two times larger compared to the volume of KCl solution.

[tex]V_{container \, 2} = \mathbf{\displaystyle 2 \times V_{4\% \, solution}}[/tex]

The volume of the solution in container 3 = Two times larger than the container two solution volume.

[tex]V_{container \, 3} = \displaystyle \mathbf{ 2 \times V_{container \, 2}}[/tex]

Therefore;

[tex]V_{container \, 3} = \displaystyle 2 \times 2 \times V_{4\% \, solution} = \mathbf{4 \times V_{4\% \, solution }}[/tex]

Part A Required:

a. To select the container that represent the dilution of the 4% solution to 2%

Solution:

The dilution formula is; C₁·V₁ = C₂·V₂

Therefore;

[tex]\displaystyle V_1 = \mathbf{\frac{C_1 \cdot V_1}{C_2}}[/tex]

C₁ =4%, C₂ = 2%, we get;

[tex]\displaystyle V_1 = \frac{4 \cdot V_1}{2} = 2 \cdot V_1[/tex]

The volume of the container that represents a 2% dilution is container 2

which is filled with a solution of a volume two times larger compared to the

KCl solution.

Part B:

Required:

The container diluted to a 1% m/v KCl solution.

Solution;

Using the dilution formula, we have;

C₁ = 4%, C₂ = 1%

Therefore;

[tex]\displaystyle V_1 = \frac{C_1 \cdot V_1}{C_2}[/tex]

[tex]\displaystyle V_1 = \frac{4 \cdot V_1}{1} = \mathbf{4 \cdot V_1}[/tex]

The volume of the solution is four times the volume of the 4% KCl solution, which is equivalent to the volume in container 3.

Possible parts of the question are;

Select the container that represents the dilution of the 4% (m/v) KCl solution to obtain the solutions that follows;

Part A: a 2% (m/v) KCl solution

Part B: a solution that is a 1% (m/v) KCl solution

Please see attached drawings

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Which model represents the chemical formula NO2, nitrogen dioxide?

A) A.

B) B.

C) C.

D) D.​

Answers

Answer:

C

Explanation:

The answer is C, because nitrogen is in purple, and oxygen is in blue, and in NO2 you have 2 oxygen atoms.

1. If the wavelength is changed, what will happen to the absorbance values?

Answers

Answer:

The longer the path length, the more molecules there are in the path of the beam of radiation, therefore the absorbance goes up. As you likely know from other experiences, a particular chemical species absorbs some wavelengths of radiation and not others

The wavelength is used to determine the concentration of a colored solution since at this wavelength a slight change in concentration allows for a significant change in the absorbance of light.

What is Wavelength?

Wavelength is the distance between equal points in adjacent cycles of a wave signal that propagates in space. Each wave has a definite shape and length, so  the distance between the peaks is called the wavelength.

It can be calculated by this formula-

[tex]\lambda=\frac{v}{f}[/tex]

[tex]where, \lambda =wavelength\\{v} = velocity\\{f} = frequency[/tex]

Absorbance measures the amount of light with a specific wavelength which a given substance prevents from passing through ii.

Thus, the wavelength is used to determine the concentration of a colored solution since at this wavelength a slight change in concentration allows for a significant change in the absorbance of light.

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The strongest intermolecular interactions between propanol (CH3CH2CH2OH) molecules arise from hydrogen bonding

a. True
b. False

Answers

The claim that the strongest intermolecular interactions between propanol molecules arises from hydrogen bonding is True.

Intermolecular forces are weaker attraction forces that are utilized to define physical characteristics of molecules such as:

boiling point temperature densitymelting points

Hydrogen bonding is an type of intermolecular forces.

It is a type of dipole-dipole interaction that only happens when a hydrogen atom is connected to the atomic element of oxygen, nitrogen, or fluorine.

From the question given, in the propanol (CH3CH2CH2OH) molecule, the hydrogen usually has a partially positive charge which attracts the partially negative charge of the oxygen.

Therefore, we can conclude that the claim is True.

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How many grams are 0.300 moles of glucose, C6H12O6?

Answers

Answer:

Explanation:

Firstly, let us calculate the molar mass of the glucose. To find the molar mass we need to add the masses of individual elements which constitute one glucose molecule.

Now, we know that

Molar mass of Carbon C=12gmol−1

Molar mass of Hydrogen H=1gmol−1

Molar mass of oxygen O=16gmol−1

Therefore, Molar Mass of glucose (C6H12O6) can be calculated as shown below

⇒ 6×12+12×1+6×16

⇒72+12+96⇒180gmol−1

Given mass of glucose = 300g

Now, we can calculate the number of moles in given mass of glucose, using the below formula,

Using the Formula numberofmoles=givenmassmolarmass we get

numberofmoles=300180 = 1.7 moles or 2 moles (approx.)

Hence the number of moles present in 300 g of glucose is 1.7 moles or 2 moles approximately.

A mixture of methanol and water was distilled using both simple distillation and fractional distillation. Which statement is NOT true

Answers

With regard to distilling the mixture of methanol and water using simple

distillation and fractional distillation, a statement that can be made that is

not true is that; Methanol and water form an azeotrope.

Reasons:

Azeotrope are liquid mixtures that have the property of a constant boiling

point due to the contents of the vapor are the same as the mixture.

Water when mixed with methanol form network structures. However,

methanol does not form a binary azeotrope with water.

Therefore, a statement that is not true is that methanol and water form an

azeotrope a mixture that has a constant boiling temperature.

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Disadvantage and advantage of iodine ?


- umoren sŭm..​

Answers

THE ADVANTAGE OF IODIN

IODINE CAN LEAD TO GOITER AND OTHER THYROID PROBLEMS.

THE DISADVANTAGE OF IODIN

IODIN MAY LEAD TO THYROIDITIS AND THYROID PAPILLARY CANCER

Cesium-137 is part of the nuclear waste produced by uranium-235 fission. The half-life of cesium-137 is 30.2 years. How much time is required for the activity of a sample of cesium-137 to fall to 8.32 percent of its original value

Answers

Answer:

la primera va con la última

In experiment 9, in one operation, we heat up the alcohol with acid and do a concurrent distillation. What was the purpose of doing this

Answers

Answer:

we heat up because the component with lower boiling evaporates first,

leaving the other behind


Question 2
Which of the following models the arrangement of atoms in a gas?

O None of these

PLEASE HELP ASAP

Answers

Answer:

The option where the atoms are furthest apart.

Explanation:

Gasses are the most energetic of the three basic states of matter, their atoms have more kinetic energy than either solids or liquids and will therefore also have the most spread out atoms.

Which stage of a fire can be described as follows: The flames are not visible and the combustible item no longer generates heat or combustion products

Answers

Fire extinguishment is referred to the stage in which flames are not visible

and the combustible item no longer generates heat.

This stage refers to when the fire has been put out through a fire

extinguisher or other compounds.   When fire is put out, there is no longer

flames present.

The absence of flames also means that there is no heat generation or

combustion products due to the absence of a heat source.

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từ một dung dịch có pH=7 muốn tạo thành dung dịch có pH nhỏ hơn 7 thì cho vào dung dịch

Answers

Answer:

you lift my feet off the ground spin me around you make me crazier crazier

Which of the following is NOT a type of evidence indicating that a chemical change has occurred? *

- fizzing/bubbling
- heat is released
- solubility
- sound is given off

Answers

Answer:

sound is given off

Explanation:

due to a number of scientific research sound that is given off of an object is not due to a chemical reaction.

What are the dependent and independent variables in this experiment? How are outside factors being controlled in this experiment to make sure that the results test only the dependent variable?

Answers

Answer:

1. An independent variable is manipulated, or changed. The dependent, or responding variable, changes based on the independent variable. The dependent variable is examined.

2. It is a controlled experiment.

Explanation:

In a controlled experiment all variables are kept the same, except for the one being tested, which is called the experimental variable , or independent variable . This group is the experimental group . The group that is not affected by the experimental variable is the control group .

Very often a graph will be used to analyze the results of the experiment. The independent/experimental variable is placed on the x-axis and the dependent variable is placed on the y-axis. The dependent variable is what is measured as a result of the application of the experimental variable.

A variable that is independent is altered. Based on the independent variable, the responding variable, or dependent variable, alters. Examining the dependent variable. The experiment is carefully controlled.

What is an independent variable ?

In mathematical modeling, statistical modeling, and experimental sciences, there are dependent and independent variables. Dependent variables get their name because, during an experiment, their values are investigated under the presumption or requirement that they are dependent on the values of other variables due to some law or rule.

A variable that is independent is precisely what it sounds like. It is a stand-alone variable that is unaffected by the other variables you are attempting to assess. Age, for instance, could be an independent variable.

When doing an experiment, the independent variable is what you alter, and the dependent variable is what changes as a result of that change. This is an easy way to conceive of independent and dependent variables.

Thus, based on the independent variable, the responding variable, or dependent variable, alters.

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