What is the only way to be certain that a chemical change has occurred

Answers

Answer 1

Answer:

New kinds of products forms and the reaction is not easily reversible.

Explanation:

The only way to be certain that a chemical change has occurred is by finding out if new kinds of products have been formed.

A chemical change is a change in which new kinds of matter is formed. It is always accompanied by energy changes.

The process is not easily reversible.

Examples of chemical changes are combustion, rusting of iron, precipitation and souring of milk.


Related Questions

How many moles of ethane gas, C2H6(g), will occupy 15.0 L at 30 degrees Celsius and 5.0 atm?

Answers

Answer:

3 mol

Explanation:

Given data:

Volume of ethane = 15.0 L

Temperature = 30°C

Pressure = 5.0 atm

Number of moles of ethane = ?

Solution:

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

Now we will convert the temperature.

30+273 = 303 K

5.0 atm × 15.0 L = n×0.0821 atm.L/ mol.K   × 303 K

75 atm.L =  n× 24.87 atm.L/ mol

n = 75 atm.L / 24.87 atm.L/ mol

n = 3 mol

A mixture is made by combining 1.29 lb of salt and 5.35 lb of water.
What is the percentage of salt (by mass) in this mixture?

Answers

Answer:

19.47%

Explanation:

[tex]\frac{1.29}{1.29+5.35}[/tex]

Please recheck, for this answer may not be correct

Which of the following does NOT determine local weather patterns?

Answers

Answer:

do you have a picture of the choices?

The table below shows properties of two compounds at standard pressure. Which statement classifies the two compounds? 1)Both compounds are ionic, 2)Both compounds are molecular, 3) Compound 1 is ionic, and compound 2 is molecular, 4)Compound 1 is molecular, and compound is ionic

Answers

Answer:

answer of this question is option. 3. compound 1 is ionic ,and 2 is molecular

Compound 1 is ionic and compound 2 is molecular. The correct option is 3) Compound 1 is ionic, and compound 2 is molecular

From the question,

We are to classify the compounds according to the information provided in the table

First,

We will list the properties of ionic and molecular compounds

Properties of ionic compounds

The exist as solid at room temperature. They generally have high melting and boiling temperatures. They are good electrical conductors when molten or in solution.

Properties of molecular compounds

They can exist as solid, liquid or gas.They generally have low melting and boiling temperatures. They are poor electrical conductors.

In the given table,

Compound 1 has high melting and boiling points, and it is a good electrical conductor. Therefore, compound 1 is ionic

Compound 2 has low melting and boiling points, and it is a poor electrical conductor. Therefore, compound 2 is molecular

Hence, Compound 1 is ionic and compound 2 is molecular. The correct option is 3) Compound 1 is ionic, and compound 2 is molecular

Learn more on properties of ionic and molecular compounds here: https://brainly.com/question/13878434

Sulfur dioxide (SO2) is an unwelcome result
of burning soft coal in power plants. Some
of the SO2 ends up as sulfuric acid in acid
precipitation. The net reaction is
2 SO2(g) + O2(g) + 2 H2O(l) —— 2 H2SO4(l)
What mass in grams of SO2 is needed to
react with 1771 g of O2?
Answer in units of g.

Answers

Answer:

I believe it is 1771 divided by 4

Explanation:

How many liters are in 7.41 x 1026 atoms of helium (He) at STP?

Answers

Answer:

Explanation: Avogadro number,N, = 6.02214076*10^23per mole —> 22.71L

—>( 7.41*10^26/N)*22.71 = 22.79*10^3 = 22,790L

what is a physical quantity​

Answers

A quantity that can be measured physically.


6. Three of these terms belong together. Which one doesn't belong?
A) nucleus
B) cytoplasm
C) cell wall
D) cell membrane
Explain why the one you chose doesn't belong with the other three?

Answers

Answer:

i am 50/50 at the memoent but i have a feeling it is the cytoplasm as it isnt a cell like the others. Hope this helps :(

Explanation:

PLEASE HELP PLEASE LLEASE HELP, WILL MARK BRAINLIEST!!!

Which of the following elements will NOT reach an octet when in a bond?

Answers

Answer:

Hydrogen

Explanation:

Mount Everest is 29,029 feet high. What is
the height of Mount Everest in kilometers?

Answers

Answer:

8.849 kilometres

Explanation:

this is the height in kilometers

9. What metric unit would be most
appropriate to use when measuring
the length of a paperclip?
a. Millimeter
b. Decimeter
c. Meter
d. Kilometer

Answers

Answer: a. Millimeter

Explanation:

A paperclip is a small device or instrument that can be used to hold the papers or stack of papers together. The length of the paperclip can be measured using millimeter. It is equal to the thousands of meters. The millimeter is a dimension which is used to measure the very small length objects which have visible scale distances and length.

Decimeter can be used to measure the length of the object smaller than paperclips. Meter and kilometers are used for objects and distances larger than paperclip.

How are electricity and magnetism related?
Electricity and magnetism are not related.
Moving magnets can make electrical currents.
Electricity can create a magnetic field.
Protons and electrons are repelled by magnets.
NEED HELP NOW

Answers

Answer:How are electricity and magnetism related?

Moving magnets can make electrical currents.

Electricity and magnetism are not related.

Protons and electrons are repelled by magnets.How are electricity and magnetism related?

Moving magnets can make electrical currents.

Electricity and magnetism are not related.

Protons and electrons are repelled by magnets.

Explanation:

What are the names of the compounds containing silver?
Show the compound formula and their names. (WRITE CLEARLY AND NEATLY OR THE QUESTION WILL BE CONSIDERED WRONG)

Answers

Answer:

the silver compounds include:

silver chloride agcl ,

silver bromide agbr ,

and silver iodide agi.

How do you know when to put a positive or negative exponent?

Answers

Answer:

If a negative number is raised to an even power, the result will be positive. If a negative number is raised to an odd power, the result will be negative. The negative number must be enclosed by parentheses to have the exponent apply to the negative term.

Explanation:

How much volume (in cm3) is gained by a person who gains 12.3 lb of pure fat?

Answers

Answer:

So we are given with the mass while we are asked for the amount of volume. So this means, we must need an information on the density. From literature, the density of human fat is 0.918 g/cm³. Convert grams to lb by the conversion that 1,000 g = 2.2 lbs.

Density = 0.918 g/cm³ * (2.2 lbs/1,000 g) = 0.0020196 lb/cm³

Volume = Mass/Density = 12.2 lb / 0.0020196 lb/cm³

Volume = 6,040.8 cm³

HELPPPPPPPPPPPPPPPPPP

Answers

Answer:

*helps and doesnt get deleted*

Explanation:

The following is a procedure that was theoretically performed by a student. Read through the procedure and answer the questions below.1.A 10.0 mL graduated cylinder to measure 10.0 mL of a 1.00 M CaCl2 solution into an initially empty 50.0 mL beaker.2.A 50.0 mL graduated cylinder was then used to measure out 25.0 mL of 0.500 M K2CO3. This K2CO3solution was then added to the beaker containing the CaCl2 solution. The solution became cloudy, and the student concluded that a precipitate must have formed. Write a balanced chemical reaction below, including phases, and identify the chemical formula of the precipitate:

Answers

Answer:

CaCl2 (aq) + K2CO3(aq) ---------> CaCO3(s) + 2KCl(aq)

Explanation:

We have the reactants as calcium chloride and potassium carbonate. Recall that we are expecting that the reaction will yield a precipitate. We must keep that in mind as we seek to write its balanced chemical reaction equation.

So we now have;

CaCl2 (aq) + K2CO3(aq) ---------> CaCO3(s) + 2KCl(aq)

Recall that the rule of balancing chemical reaction equation states that the number of atoms of each element on the right side of the reaction equation must be the same as the number of atoms of the same element on the left hand side of the reaction equation.

a. Use the balanced equation C3H8 + 5O2 -> 3CO2 + 4H2O to answer the following questions
i. How many moles of CO2 are produced from 5 moles 02? (1 point)

ii. How many grams of CO2 are produced from 5 moles O2? (2 points)
iii how many grams of CO2 are produced from 128.00g O2? (2 points)

Answers

Answer:

i. 3 moles.

ii. 132.03 grams.

iii. 105.6 grams.

Explanation:

Hello!

In this case, given the balanced chemical reaction, we can proceed as follows:

i. By starting with 5 moles of oxygen, via the 5:3 mole ratio we compute the produced moles of CO2:

[tex]n_{CO_2}=5molO_2*\frac{3molCO_2}{5molO_2} =3molCO_2[/tex]

ii. Now, since we have previously computed the moles of CO2 from the same moles of oxygen, by using its molar mass (44.02 g/mol), we obtain:

[tex]m_{CO_2}=3molCO_2*\frac{44.01gCO_2}{1molCO_2} =132.03gCO_2[/tex]

iii. Now, we need to combine the previously used two proportional factors for the calculation of the mass of CO2 from 128.00 grams of oxygen (molar mass 32.00 g/mol):

[tex]m_{CO_2}=128.00gO_2*\frac{1molO_2}{32.00gCO_2}*\frac{3molCO_2}{5molO_2}*\frac{44.01gCO_2}{1molCO_2}\\\\m_{CO_2}=105.6gCO_2[/tex]

Best regards!

atom ,molecule, proton neutron electron, elements/compounds from SMALLEST to the BIGGEST.

Answers

Answer:

Electron,Protons/Neutrons,Atom,Molecule

Explanation:

Draw a Lewis structure of the molecule that matches the description below. All non- H atoms should have full octets, and all formal charges should be zero. Unless you're told otherwise, assume there are no rings in the molecule.
Description: The molecule is composed of
2 C 's, 5 H 's, and 1 N and it contains a C - C double bond.

Answers

Answer:

See attached picture.

Explanation:

Hello!

In this case, according to the given instructions, on the attached picture you will find the required Lewis structure, whereas there is a double bond between the two carbon atoms, and one of those is bonded to the nitrogen; moreover the terminal carbon has two out of five hydrogen atoms, the middle carbon, one out of five and the nitrogen atom has two out of five hydrogen atoms; therefore the molecule would be ethenamine.

Best regards!

Which of these can be found in a plant cell, but not in an animal cell?

Answers

Answer:

Hey!

Explanation:

I dont know the answers but Cell walls and Cloroplasts are only in plant cells. I hope this helps!

A .......... notifies you that danger is present if the directions are not followed.

•A . Warning
•B.Hazard
•C. Safety
•D. Danger

Answers

Answer:

A. Warning

Explanation:

Out of all said choices, the best choice would be warning since it would fit the sentence the most.

"A Warning notifies you that danger is present." compared to:

"A Hazard notifies you that danger is present."

"A Safety notifies you that danger is present."

"A Danger notifies you that danger is present."

which mineral is composed of calcium and fluorine?

Answers

Answer:

Fluorite

What is Fluorite? Fluorite is an important industrial mineral composed of calcium and fluorine (CaF2). It is used in a wide variety of chemical, metallurgical, and ceramic processes

Exactly what the first person said. Fluorite.

Classify each of the observed changes according to whether or not they are likely to represent evidence that a chemical reaction is occurring when performing an experiment.
May be evidence of a chemical reaction Not evidence of a chemical reaction
a solution color becoming less intense
due to dilution
bubbles (sas formation) changes in color
precipitation
explosion or fire
Answer Bank
a solid liquifying change in temperature solution colors mixing

Answers

Answer:

a solution color becoming less intense  due to dilution- is not an evidence of a chemical reaction

bubbles (gas formation) - evidence of a chemical reaction

explosion or fire - evidence of a chemical reaction

changes in color- evidence of a chemical reaction

precipitation- evidence of a chemical reaction

changes in temperature - evidence of a chemical reaction

a solid liquifying - is not an evidence of a chemical reaction

solution colors mixing - is not an evidence of a chemical reaction

Explanation:

A chemical change is not easily reversible and yields new substances. It is often accompanied by a loss or gain of heat.

In the answer section, i have shown some evidences that lead us to conclude that a chemical reaction has taken place. The occurrence of a chemical change often goes with the formation of new substances as earlier stated and any of these signs may accompany the process.

For instance, when a metal is dropped in dilute acid solution, bubble of hydrogen gas indicates that a chemical reaction has taken place.

You have a 500.0 ml graduated cylinder filled with 100.0 mL of water. You carefully add a 178.5 gram piece of iron (density of iron = 7.87 g/mL). What is the final volume reading in the graduated cylinder after adding the iron piece?​

Answers

Answer:

122.7 mL

Explanation:

Step 1: Given data

Volume of water: 100.0 mLMass of the piece iron (m): 178.5 gDensity of iron (ρ): 7.87 g/mL

Step 2: Calculate the volume of the piece of iron

Density is equal to the mass of the piece divided by its volume.

ρ = m/V

V = m/ρ

V = 178.5 g/(7.87 g/mL) = 22.7 mL

Step 3: Calculate the volume of the mixture

The volume of the mixture is equal to the sum of the volume of water and the iron piece.

100.0 mL + 22.7 mL = 122.7 mL

Isopropanol burns in oxygen to yield carbon dioxide, water, and heat. Which word equation best represents this chemical reaction?
isopropanol Right arrow. carbon dioxide + water + heat
isopropanol Right arrow. carbon dioxide + water + oxygen
isopropanol + oxygen Right arrow. carbon dioxide + water + heat
isopropanol + oxygen + heat Right arrow. carbon dioxide + water

Answers

Answer:

isopropanol + oxygen Right arrow. carbon dioxide + water + heat

Explanation:

Word equation:

isopropanol + oxygen    →   carbon dioxide + water + heat

Chemical equation:

2C₃H₇OH  + 9O₂       →     6CO₂ + 8H₂O + Heat

The given reaction is combustion of isopropanol. Isopropanol burn in the presence of oxygen and produced carbon dioxide and water. Heat is also produced in this reaction.

The given reaction also follow the law of conservation of mass. There are equal number of moles of each element on both side of reaction equation thus mass remain conserved.

isopropanol + oxygen Right arrow. carbon dioxide + water + heat

The following information should be considered:

Word equation:

isopropanol + oxygen    →   carbon dioxide + water + heat

Chemical equation:

[tex]2C_3H_7OH + 9O_2 \rightarrow 6CO_2 + 8H_2O + Heat[/tex]  

The given reaction is combustion of isopropanol. Isopropanol should be burn with the presence of oxygen and generated carbon dioxide and water. Heat is also generated in this reaction. The given reaction also follows the law of conservation of mass

Learn more; https://brainly.com/question/1691136?referrer=searchResults

Uranium (VIII) Sulfide formula

Answers

Answer:

US₂

Explanation:

Uranium sulfide (US₂)

Uranium atomic symbol = U

Sulfur atomic symbol = S

Uranium valency = +4

Sulfur valency = -2

So;

Uranium sulfide (US₂)

Based on the number of valence electrons indicated by its location in the periodic table ,which elements behavior would you predict to be closest to that of potassium (k)

Answers

Answer:

Na sodium or Rb rubidium

Explanation:

Because Na is present in first group all members of group 1 have 1 electron in valence shell and show similar properties.

How many grams are in 4.58x1023 atoms of oxygen?

Answers

4685.34 atoms of oxygen

What is the length of an average solar cycle? A. 5 years B. 11 years C. 22 years D. 10 years

Answers

B. A solar cycle usually lasts 11 years.
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