formation of a solid, formation of a gas, and a color change can also occur during some physical changes. give examples of physical changes that could produce these clues. what evidence suggests that the changes you observed in test tubes 1-3 were, in fact, chemical changes

Answers

Answer 1

Answer:

Examples of these physical changes are melting ice-cream, or boiling water as well as freezing it. Adding dye to water is also a physical change since the chemical compounds remain the same, it is only the physical appearance that changes.

Possible reasons for chemical changes are the formation of a precipitate (solid), or formation of gas (bubbling) as well as release of heat or light or release of odor.


Related Questions

What does it mean a solution is a weak base"? What about a "Strong base"? Give logical pH values for each

Answers

Answer:

A weak base is a base that, upon dissolution in water, does not dissociate completely, so that the resulting aqueous solution contains only a small proportion of hydroxide ions. PH 7-10

A strong base is a base that is completely dissociated in an aqueous solution. a PH of about 12-14

If you dispense 40 ml of hexane, but it turns out you only need 5 ml, what should you do with the remainder?

Answers

After subtracting the volume needed from the volume dispensed, we got a remainder of 35ml

Subtraction of Numbers

Given Data

Volume of Hexane dispensed = 40mlVolume needed = 5 ml

Let us compute the amount of excess hexane/ the volume that will remain

Remainder = The difference in volume dispensed and the volume needed

Remainder = 40-5

Remainder = 35 ml

The remainder is 35ml

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If you dispense 40 ml of hexane, but it turns out you only need 5 ml, then we should have 35 mL of remained hexane.

How would we calculate the remaining volume?

Remaining volume of any liquid will be calucted as:

Remaining Volume = Total volume - Used volume

Given that, total volume of hexane = 40 mL

Used volume of hexane = 5 mL

On putting values in above equation, we get

Remaining volume = 40 - 5 = 35 mL

Hence required value of remaining volume is 3 mL.

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Are all black holes the same size? Explain

Answers

Answer:

According to my search, the answer is this.

Black holes come in several different sizes which are defined by their mass. Small black holes are usually the result of a relatively short and violent collapse of a star.

Explanation:

It only has mass. The amount of matter that has fallen into the black hole determines its mass. The more mass/matter a singularity has the larger its event horizon. So, the greater the black hole's mass the larger it is.

Answer: Black holes come in several different sizes which are defined by their mass. Small black holes are usually the result of a relatively short and violent collapse of a star.

Explanation:

A mixture of three gases has a total pressure of 94.5 kpa. if the partial pressure of
the 1st gas is 65.4 kpa and the partial pressure of the 2nd gas is 22.4 kpa, what is the
partial pressure of the 3rd gas of the mixture?

Answers

Answer: 6.7 kPa

Explanation:

Pressure Total = P(partial 1) + P(partial 2) + P(partial 3) →

94.5 kPa = 65.4 kPa + 22.4 kPa + P(partial 3) →

6.7 = P(partial 3) :)

Given:-Partial pressure of 1st gas ,P[tex]_1[/tex]= 65.4 kpapartial pressure of 2nd gas ,P[tex]_2[/tex]= 22.4 kpaTotal pressure,P[tex]_o[/tex] = 94.5 kpa

To Find :-partial pressure of the 3rd gas,P[tex]_3[/tex]

Solution:-

According to the Dalton's law of partial pressures the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures exerted by each individual gas in the mixture.

So, P[tex]_o[/tex] = P[tex]_1[/tex]+ P[tex]_2[/tex]+ P[tex]_3[/tex]

[tex]\longrightarrow[/tex]94.5 = 65.4+ 22.4 + P[tex]_3[/tex]

[tex]\longrightarrow[/tex]94.5 = 87.8+ P[tex]_3[/tex]

[tex]\longrightarrow[/tex] P[tex]_3[/tex] = 94.5 - 87.8

[tex]\longrightarrow[/tex]P[tex]_3[/tex] = 6.7 kpa

Therefore, partial pressure of the 3rd gas of the mixture is 6.7 kpa .

Draw the structures of the aldol addition and condensation products of cyclopentanone

Answers

The term aldol condensation has to do with a reation in which a nucleophile attacks the carbonyl group of an aldehyde.

What is alodol condensation?

The term aldol condensation has to do with a reation in which a nucleophile attacks the carbonyl group of an aldehyde or a ketone to convert it to the enolate from which attacks another aldehyde or ketone at the carbonyl carbon to form the required product.

The structure of the organic product from the aldol condensation involving cyclopentanone is shown in the image attached to this answer.

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If 1. 3618 moles of AsF3 are allowed to react with 1. 0000 mole of C2Cl6, what would be the theoretical yield of AsCl3, in moles

Answers

Answer:

AsF3:C2CI6

4:3

1.3618 moles: 1.02135 moles(1.3618÷4×3)

C2CI6 is the limting reagent

So the number of moles for AsCI3 is 0.817 moles( number of moles of the limting reagant) ÷3 ×4 (according to ratio by balancing chemical equation)=1.09 moles(3 s.f.)

or

Balanced equation

4AsF3 + 3C2Cl6 → 4AsCl3 + 3C2Cl2F4

Use stoichiometry to calculate the moles of AsCl3 that can be produced by each reactant.

Multiply the moles of each reactant by the mole ratio between it and AsCl3 in the balanced equation, so that the moles of the reactant cancel, leaving moles of AsCl3.

Explanation:

6.
The temperature of a 250.0 g ball of iron increases from 19 C to 32 C. How much heat
did the iron ball gain?
The temperature of a 250.0 g ball of iron increases from 19 C to 32 C. How much heat
did the iron ball gain?

Answers

Q = mc∆T.

the specific heat capacity of iron is 0.450. 250 × 0.450 × (32-19) = 1462.5J

How is an element called if the number of neutrons exceed the number of protons?.

Answers

Answer:

In a heavier nucleus, the repulsive force between the protons is very high. For stability, the nuclear force must dominate this electrostatic repulsive force. This is possible if the number of neutrons is greater than number of protons.

Arrange the following bonds in order of increasing ionic character. assign number 1 as the highest and 6 as the lowest. a. carbon-hydrogen
b. fluorine-hydrogen
c. bromine-hydrogen
d. sodium-chlorine
e. potassium-fluorine
f. lithium-chlorine

Answers

Answer: Potassium to fluorine, fluorine to nitrogen, bromine to hydrogen, carbon to hydrogen, lithium to chlorine, sodium to chlorine.
Explanation:
Ionic bond is greater when the electronegativity difference existing between the two atoms are large causing the bonding to be more polar.

help ty! I just need help with the third one

Answers

Answer:

D

Explanation:

because if a flea is on a dog that is a parisite to host relashionship

Answer:

for number 3 is D

Explanation:

but i am not 100% sure of that

What does a coefficient tell you?

Answers

 The coefficient tells you how many molecules of that substance there is. 

The molar mass of water (h2o) is 18.0 g/mol. a sample of water has a mass of 18.0 g. how many moles of water are contained in this sample? 1.00 mole 18.0 moles 36.0 moles 324 moles

Answers

The moles of water are contained in the given sample is 1 mole.

How do we calculate moles?

Moles of any substance will be calculated by using the below formula:

n = W/M , where

W = required mass

M = molar mass

Given molar mass of H₂O = 18.0 g/mol

Given mass of H₂O = 18.0 g

Moles of H₂O = 18.0 g / 18.0 g/mol = 1 moles

Hence option (1) is correct.

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Answer:

A. 1.00 Mole

Explanation:

edg 2023

ohesion between water molecules contributes to __________ which allows the molecules to stick together and resist outside forces.

Answers

Answer: I believe the answer is surface tension :)

What is ∆H for the reaction of sulfur dioxide with oxygen?


2SO2(g) + O2(g) → 2SO3(g)


(∆Hf0 SO2(g) = –296.8 kJ/mol; ∆Hf0 SO3(g) = –395.7 kJ/mol)

A.)–98.9 kJ

B.)–197.8 kJ

C.)1.385 × 103 kJ

D.)197.8 kJ

Answers

Answer:

B.) –197.8 kJ

Balanced equation : 2SO(g) + O(g) → 2SO(g)

Given:

SO₂(g) = –296.8 kJ/molSO₃(g) = –395.7 kJ/mol

================================================================

products : 2 ( –296.8 ) + O₂ = -593.6 kJ/mol + Oreactant : 2 (  –395.7 ) = -791.4 kJ/mol

products energy = reactant energy

-593.6 + O₂ = -791.4

O₂ = -791.4 - ( -593.6)

O₂ = –197.8 kJ

why is the non-luminous flame preferred for heating?

Answers

Answer:

Because it is the hottest zone

Answer:

the non luminous flames are very hot. little light is produced by non luminous flames.

1.
What is the concentration of a saline solution
with 234.0 grams of NaCl per 250.0 mL of solution?

Answers

Answer:

16.015668 M

Explanation:

Concentration is mols/L

nacl molar mass is 58.44277 g/mol

moles = mass/molar mass

moles = 4.00391699

4mol/0.250L = 16.015668 M solution

Based on the ksp experiment describe a way to soften water by removing calcium ions

Answers

Addition of sodium carbonate is a way to soften water by removing calcium ions

How calcium ions are removed?

Water can be softened by the addition of lime to precipitate the calcium as carbonate. Sodium carbonate is also added to remove the remaining calcium salts and to make the water soft.

So we can conclude that addition of lime or sodium carbonate is a way to soften water by removing calcium ions.

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A process based on ksp experiment to soften the water by removing calcium ions is by ion exchange resin process in which the calcium ion is substituted by a sodium ion.

What is removing calcium ions from water?

The water containing a large number of calcium ions is called hard water.

Hard water is not suitable to use.

To remove calcium ion or soften the water, there are various methods are used.

They are ion exchange resin, distillation, and sodium hydroxide.

Thus, a process based on ksp experiment to soften the water by removing calcium ions is by ion exchange resin process in which the calcium ion is substituted by a sodium ion.

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A gas sample has a temperature of 19 °C with an unknown volume. The
same gas has a volume of 464 mL when the temperature is 90. °C, with no
change in the pressure or amount of gas.

Answers

Answer: 373 mL

Explanation:

Since there is no change in pressure, the formula: V / T = V / T can be used.

However, you must first convert the temperatures to Kelvin by adding 273 to them:

(19 + 273) = 292K and (90 + 273) = 363K.

Now, plug in: V / 292 = 464 / 363 → V = 373 mL :)

The addition of a catalyst to a system at equilibrium will increase the rate of:.

Answers

Answer:

forward and reverse reaction rates

Explanation:

meaning the equilibrium is reached faster. So if the reaction is already at equilibrium there will be no effect on a concentration-time or moles-time graph.

A chemist is studying a chemical compound that
has equal numbers of carbon atoms and hydrogen atoms. She calculates that the
carbon atoms have a mass of 24 grams. What is the mass of the hydrogen atoms?
Explain your reasoning.

Answers

It should be 24 they both have to be equally the same

The mass of hydrogen atoms in the compound would be 2 grams.

Stoichiometric calculation

The carbon atoms in the compound have a mass of 24 grams.

One carbon atom has a mass of 12 grams. Thus, there are two (12 x 2 = 24) carbon atoms in the compound.

This means that there are also two hydrogen atoms in the compound. One hydrogen atom weighs 1 gram. Hence, the mass of the hydrogen atoms in the compound will be 2 grams.

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Explain why air resistance is a contact force and gravity is a non-contact force.

Answers

Answer:

The air resistance is a special type of frictional force that acts upon objects as they travel through the air. The force of air resistance is often observed to oppose the motion of an object. This force will frequently be neglected due to its negligible magnitude (and due to the fact that it is mathematically difficult to predict its value). It is most noticeable for objects that travel at high speeds (e.g., a skydiver or a downhill skier) or for objects with large surface areas. Air resistance is a contact force.

The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself. By definition, this is the weight of the object. All objects upon earth experience a force of gravity that is directed "downward" towards the center of the earth. Gravitational force is considered to be a non-contact force because it is an attracting force which does not include contact between the objects to exert force

100 pOiNtS
Explain why the vapor pressure of a solution differs from that of the pure solvent
Explain why the freezing point of a solution differs from that of the pure solvent
Explain why the boiling point of a solution differs from that of the pure solvent

Answers

Answer:

Answer one:
Solute particles block some of the ability of liquid particles to evaporate. We can then conclude, solutions of solid solutes typically have a lower vapor pressure than pure solvents.

Answer two:
Solutions freezing points are lower than of the pure solvent or solute because freezing (becoming a solid) creates order and decreases entropy.

Answer three:
The presence of solute particles decreases the vapor pressure of the liquid solvent, this means a higher temperature is needed to reach the boiling point.


Explanation:

Have a great rest of your day
#TheWizzer

PLEASE HURRY THIS IS DUE IN 4 MINUTES!!! 3. In the understory, all of the following are true except
A. The understory has a hot, humid environment.
B. Leaves are bigger in the understory than the other layers because not much sunlight reaches this area.
C. Jaguars and leopards live in the understory.
D. Insects, bees, ants, and beetles live in the understory.

Answers

Answer:

WHERES THE UNDER STORY! POST IT QUICK AND ILL HELP

Explanation:

6. How did humans help the bison from being hunted to extinction?

Answers

Answer:

✒️Answer:

Bison were saved through the combined efforts of conservationists, scientists, ranchers and ultimately the general public. As their comeback continues, I believe that they can teach us how to be better stewards of the land and provide a future for the Plains where ecosystems and human cultures thrive.

Explanation:

#CarryOnLearning

[tex]watch.some.anime[/tex]

Hydrogen peroxide and potassium permanganate balanced equation

Answers

Answer:

2 KMnO4 + H2O2 → 2 MnO2 + 2 O2 + 2 KOH - Balanced equation

How do the names of molecular compounds differ from the names of ionic compounds.

Answers

Long Answer:

Ionic: Cation is named first followed by the anion.

If it's an ionic compound with a transition metal, there are more than one possible ion. Molecular - named with the least electronegative ion first + prefixes are given to both ions to indicate number of atoms in each element.

Short Answer: Ionic compounds- Cation is named first, followed by the anion.

When a solution of mgcl2 and one of agno3 are mixed, the net ionic equation is:

Answers

When a solution of MgCl₂ and a solution of AgNO₃ are mixed, the net ionic equation obtained is:

2Cl¯(aq) + 2Ag⁺(aq)  —> 2AgCl(s)

What is a chemical equation?

Chemical equations are representations of chemical reactions using symbols and formula of the reactants and products.

The reactants are located on the left side while the products are located on the right side.

Reactants —> Products

The balancing of chemical equations follows the law of conservation of matter which states that matter can neither be created nor destroyed during a chemical reaction but can be transferred from one form to another.

How to write the net ionic equation

In solution

MgCl₂(aq) —> Mg²⁺(aq) + 2Cl¯(aq)

AgNO₃(aq) —> Ag⁺(aq) + NO₃¯(aq)

The reaction proceeds as follow

MgCl₂(aq) + AgNO₃(aq) —>

Mg²⁺(aq) + 2Cl¯(aq) + 2Ag⁺(aq) + 2NO₃¯(aq) —> 2AgCl(s) + Mg²⁺(aq) + NO₃¯(aq)

Cancel out the spectator ions (i.e Mg²⁺ and NO₃¯) to obtain the net ionic equation

2Cl¯(aq) + 2Ag⁺(aq)  —> 2AgCl(s)

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When a solution of MgCl₂ and one of AgNO₃ are mixed, the net ionic equation is 2Cl¯(aq) + 2Ag⁺(aq) → 2AgCl(s).

What are net ionic reactions?

Net ionic reactions are those reactions in which each species are written in their respective ions form except the spectator ions.

Given chemical reaction is:

MgCl₂(aq) + 2AgNO₃(aq) → 2AgCl(s) + Mg(NO₃)₂(aq)

Ionic form of the given reaction will be written as

Mg²⁺(aq) + 2Cl¯(aq) + 2Ag⁺(aq) + 2NO₃¯(aq) → 2AgCl(s) + Mg²⁺(aq) + NO₃¯(aq)

Spectator ions are those which are commonly present on both side of the reaction and for this reaction they are Mg²⁺ and NO₃¯. So the net ionic reaction will be:

2Cl¯(aq) + 2Ag⁺(aq) → 2AgCl(s)

Hence required net ionic reaction is 2Cl¯(aq) + 2Ag⁺(aq) → 2AgCl(s).

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In a triprotic acid, which ka has the highest value?.

Answers

Answer:

The answer is Ka1

▬▬▬▬▬▬▬▬

When it comes to dissociation, Ka1 is fairly the most even-out level, classifying it as a Weak Acid.

What differentiates a weak from a strong acid?

They must be fully separable into ions. If that's the case, you are dealing with a Strong acid.

If this is not the case, that would make the acid Weak.

▬▬▬▬▬▬▬▬

In conclusion, I hope this helps you and I hope you have a great day!

How many liters of carbon gas are in 13.7 moles of carbon dioxide gas at STP?

Answers

At STP

1 mol weighs 22.4L

No of moles=13.7mol

Total volume:-

13.7(22.4)306.88L[/tex]

The volume of gas occupied by 13.7 moles at STP is 306.88L.

What is STP?

STP stands for standard temperature and pressure. STP refers to a specific pressure and temperature used to report on the properties of matter.

According to IUPAC( International Union of Pure and Applied Chemistry), it is defined as -

Temperature of 0 degree celsius (273K)Pressure of 1 atm

It is generally needed to test and compare physical and chemical processes where temperature and pressure plays an important role as they keep on varying from one place to another.

One mole of a gas under STP conditions occupies a volume of 22.4L.

Given,

Moles of carbon dioxide gas = 13.7 moles

We know that,

1 mole of a gas occupies 22.4 L of volume at STP.

Thus, 13.7 moles will occupy 13.7 × 22.4 L

                                              = 306.88 L

Therefore, the volume of gas occupied at STP is 306.88L.

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Which of the following are duplicated during cell division in a human cell?.

Answers

All cell constituents are duplicated during cell division in a human cell i.e. mitosis and meiosis type of cell division.

What are duplicated during cell division in a human cell?

During mitosis, a cell duplicates all of its internal parts and formed two identical daughter cells. During duplication, all parts have two sets which is equally distributed into two daughter cells in mitosis type of cell division.

While on the other hand, during meiosis, a cell divides into four daughter cells having haploid chromosomes i.e. half number of chromosomes.

So we can conclude that cell constituents are are duplicated during cell division in a human cell.

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