Which of these is NOT evidence that a chemical change has taken place?

temperature rising when 2 substances are mixed

gas production

color change

melting

Answers

Answer 1
melting, that’s the sign on a physical change

Related Questions

A solid substance was tested in the laboratory. The test results are listed below: 1.) dissolves in water 2.) is an electrolyte 3.) melts at a high temperature. Based on these results, the solid substance could be

Answers

Answer:

NaCl may be i guess so....


Weathering is a constructive process.
True or false

Answers

Answer: true

Explanation: Collection and analysis of data indicates that constructive forces include crustal deformation, faulting, volcanic eruption and deposition of sediment, while destructive forces include weathering and erosion.

You have two pure substance that you cannot identify. Each sample is solid at room temperature. Describe at least five steps in the appropriate sequence that you would take to be able to identify the substance. ​

Answers

Answer:

pue like ad

Explanation:

For the two pure substance that you cannot identified , The steps taken in the right sequence are:

When two pure substance are places before you. you have to visually anaylse the sample, note the various colors that they have. It can tell you if it's an anions or cations.

You can use reactants to precipitate the cations of the sample you have

We then add a reactant to the sample and you did not see any precipitate, it corresponds to any of the elements or compound. If you do not see a precipitate, you can add other reactant.

You then observe the color of this precipitate. example if the color changes to green, it will tell you that the substance is Ni(OH)₂ etc.

One can also find out through the melting and boiling point of the two substances.

Pure substance are regarded as substance that does not have impurities. one common way of finding out the purity of a substance is by its melting and boiling point determination.

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What is the answer? Please

Answers

Answer:

Cell

Explanation:

I just passed this unit a month ago.

Answer:

It is 6. Cell

Explanation:

Cells make up the smallest level of a living organism such as yourself and other living things. The cellular level of an organism is where the metabolic processes occur that keep the organism alive. That is why the cell is called the fundamental unit of life.

I really hope this helped. God bless you and have a great day! :-)

How many atoms of phosphorus are in 5.70 mol of copper(II) phosphate?​

Answers

Answer:

Cu3 (PO4)2 contains a total of 2 atoms of phosphorus in just one molecule. (2.10 mol)(6.02214 x 10^23 atoms / mol)(2 phosphorous) = 2.53 x 10^24 atoms of phosphorous per molecule of copper i

Explanation:

What do chemical compounds want to obey?

Answers

Answer:

Their atoms obey the octet rule

Explanation:

Chemical compounds are formed when atoms combine with one another in order to comply with the octet rule. The octet configuration gives an atom stability in electronic structure.

When atoms become isoelectronic with noble gases, it confers a special stability on them. Therefore, to attain this state, they gain or lose electron or share their electrons with other species.

Complete the balanced molecular chemical equation for the reaction below.

If no reaction occurs, write NR after the reaction arrow.

Cu2SO4(aq) + Li3PO4(aq)

Answers

Answer:

Following are the complete balance of the given equation:

Explanation:

Given equation:

[tex]Cu_2SO_4(aq) + Li_3PO_4(aq)[/tex]

[tex]Cu_2So4\ (aq)+Li_3Po_4 \(aq) \longrightarrow Cu_3(Po_4)\ (aq)+Li_2So_4 \ (aq)[/tex]

After Balancing the equation:

[tex]3 Cu_2So4\ (aq)+ 2 Li_3Po_4\ (aq) \longrightarrow 2 Cu_3(Po_4)\ (aq)+ 3Li_2So_4 \ (aq)[/tex]

In the above equation, when the 3 mol Copper sulfate reacts with 2 mol lithium phosphate , it will produce 2 mol Copper phosphate  and 3 mol Lithium sulfate .

Which of the following belong to a category called the main group of elements
A halogens
B nonmetals
C alkaline metal
D transition elements

Answers

Answer:

C. Alkaline Metal ok thanks

C I hope it helps rkjnjjrnbejjje

Fossil fuels contribute to about 85% of the total energy produced in the world. What is a direct environmental
consequence of the extensive use of fossil fuels?

Answers

Answer:your a poop face

Explanation:

Imagine not knowing the answer

Answer: C

Explanation:

If element X has 6 valence electrons, what is the formula between element X and
magnesium.
a. X6Mg2
b. MgX3
c. MgX
d. XMg

Answers

I think it’s b but I could be wrong

Three isotopes of argon occur in nature. Calculate the average atomic mass of argon given the following relative atomic masses and abundances of each of the isotopes.

Isotope Relative Atomic Mass Abundance
Ar-36 35.97 amu 0.337%
Ar-38 37.96 amu 0.063%
Ar-40 39.96 amu 99.600%
a
35.97 amu
b
37.95 amu
c
39.95 amu
d
38.96 amu

Answers

Answer:

whats the question

Explanation:

Answer:

Calculate the average atomic mass of argon to two decimal places, given the following relative masses and abundances of each of the isotopes: argon-36 (35.97 amu; 0.337%), argon-38 (37.96 amu; 0.063%), and argon-40 (39.96 amu; 99.600%). ... So the atomic mass of Ar is 0.99639. 96 + 0.0006337. 96 + 0.00337*35.97 = 39.957.

Explanation:

hope this help

3. Theoretically how many grams of magnesium is required to produce to 5.0 g of

Magnesium oxide?

Answers

Answer:

3grams

Explanation:

The reaction for the production of Magnesium dioxide will be

Mg + O2  → MgO

we have 5g of MgO (molar mass 40g)

no of moles of MgO = 5/40 = 0.125

Using unitary method we have

1 mole of Mg require 1 mole of MgO

0.125 Mole of MgO = 0.125mole of Mg

n = given mass /molar mass

0.125 = mass / molar mass

mass = 0.125* 24 = 3grams

Elements in the same period have _____ in common?


-

Answers

Answer:

The elements that have the same number of energy levels or the orbitals.

Explanation:

They have he same number -- energy levels

A rigid container filled with a gas is placed in ice (ex. nalgene bottle). What will happen to the pressure of the gas? What do you think will happen to the volume?(Graph)

Answers

Explanation:

The pressure will decrease but the volume remains constant

in which beakers are the particles moving the most slowly

Answers

Answer:

A and D

Explanation:

Mr. Juan is husband of Maria, before they get married Maria knows that her husband cannot make a baby since he cant produce sperm. But during their 2 years in marriage, Maria got pregnant. Is Juan can file a case to Maria? What it is? Support your answer?​

Answers

Answer:

yes but first he need to check himself

Explanation:

bcoz if he cannot produce a sperm than she might have cheated him and the baby might be of someone other.

In a titration, you start with 0.05 M sodium hydroxide (NaOH) and slowly add it to 40 mL of HC1 with an unknown concentration. What is the original concentration of the HC1 if you add a total of 15.4 mL of sodium hydroxide to the HC1 to achieve pH =7?

Answers

Answer:

The original concentration of the HCl is: 0.01925 M

Explanation:

Equation:

HCl+NaOH-------> NaCl+H₂O

Volume of NaOH added = 0.05 M

No of moles of NaOH = 15.4 mL [tex]x\frac{1 L}{1000 mL} x\frac{0.05 mol NaOH}{L}[/tex]

= 0.00077 mol NaOH

Then,

Volume of HCl solution = 40 mL x 1/1000 mL

= 0.0400 L

Therefore,

Concentration of HCl = 0.00077 mol/0.0400 L

= 0.01925 M

Now, to find the pH:

pH = -log₁₀[H⁺]

     = -log₁₀(2x10⁻⁶)

     = 5.7

The properties of compund are different from the properties of their constituenr​

Answers

Answer: Atoms of carbon and hydrogen

Explanation:

Many materials, such as rocks, expand (get larger) when they are heated and contract (shrink) when they are cooled. This change
in size can cause cracks to form and break large rocks into smaller pieces.
In this example, what is caused by heating and cooling?
OA. decay
ОВ.
weathering
OC.
erosion
OD
earthquakes

Answers

Answer:

OB: weathering

Explanation:

the cycle of heating and cooling causes stresses called thermal fatigue, this causes the material to break down. In hand, weathering is a physical and chemical process that causes rocks and minerals on the Earth's surface to break down and decompose. Therefore, this matches the process you have described.

Answer:

weathering fun way to imagen it: just imagen u saw ur worst enemie and pretende it is the rock and the wind and ice and water are ur best friends THEN BAM wind and ice and water(ur best friends) make the rock(worst enemie) to dust :D

what reacts at room temperature with ethanol and also with ethanoic acid

Answers

Answer: Its esterification reaction.

when organic acid react with alcohol it forms ester and water. reaction is known as esterification reaction.

CH3COOH + C2H5OH → CH3COOC2H5 + H2O

ethanoic acid + ethanol → ethyl acetate + water

this reaction takes place in the presence of acid catalyst ( dil H2SO4).

in this reaction oxygen of ethanol with lone pair act as nucleophile and carbonyl carbon of acetic acid act as electrophile.. so its nucleophilic substitution reaction of -COOH group.

Explanation:

Ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid as a catalyst to produce the ester, ethyl ethanoate. The reaction is slow and reversible. To reduce the chances of the reverse reaction happening, the ester is distilled off as soon as it is formed.

A solution is made by adding 5.01 g of iron sulfate to 75.3 g of water. What is the mass percentage of iron sulfate in this solution?

Answers

Answer:

6.24 % of FeSO₄

Explanation:

Solute mass: 5.01 g of FeSO₄

Solvent mass: 75.3 g of water

Solution mass = solute mass + solvent mass

5.01 g + 75.3 g = 80.31 g

We can apply a rule of three. Mass percentage means the mass of solute which is contained in 100 g of solution. Then,

In 80.31 g of solution we have 5.01 g of solute

In 100 g solution, we may have (5.01  . 100)/ 80.31 = 6.24 g of solute.

This is the mass percentage: 6.24%

Sugar and Salt in water magnetism, state of matter, or solubility?
please help!!!!​

Answers

Answer:

solubility

Explanation:

Answer is solubility

Every element in group one has ______________ electron in its outer shell. Every element in group two has _______________ electrons in its outer shell.

need help

Answers

Every element in group one has 1 electron in its outer shell. Every element in group 2 has 2 electrons in its outer shell

Balance the following equations ___Fe + __O2= ___Fe3O4

Answers

3Fe + 2O2 = Fe3O4

There needs to be the same amount of each element on each side of the equation !

A gas at -20c occupies volume 140 ml calculate temperature at which the volume of the gas becomes 65 ml pressure constant

Answers

Answer:

–156 °C

Explanation:

The following data were obtained from the question:

Initial temperature (T1) = –20 °C

Initial volume (V1) = 140 mL

Final volume (V2) = 65 mL

Final temperature (T2) =?

Pressure = constant.

Next, we shall convert –20 °C to Kelvin temperature. This can be obtained as follow:

T(K) = T(°C) + 273

Initial temperature (T1) = –20 °C

Initial temperature (T1) = –20 °C + 273 = 253 K.

Next, we shall determine the new temperature of the gas as follow:

Initial temperature (T1) = 253 K

Initial volume (V1) = 140 mL

Final volume (V2) = 65 mL

Final temperature (T2) =?

V1/T1 = V2/T2

140/253 = 65/T2

Cross multiply

140 × T2 = 253 × 65

140 × T2 = 16445

Divide both side by 140

T2 = 16445 /140

T2 = 117 K

Finally, we shall convert 117 K to celcius temperature. This can be obtained as follow:

T(°C) = T(K) – 273

T2 = 117 K

T2 = 117 K – 273

T2 = –156 °C

Thus, the new temperature of the gas is –156 °C

if you a boy answer this question because............. idk

Answers

Answer:

no

Explanation:

H20+ SO3 ? Which compound is likely produced by the chemical reaction?​

Answers

Answer:

h2so4

Explanation:

im big brain.

Which cannot be chemically broken down into simpler substances?
O compound
O element
O solution
O mixture

Answers

Answer:

an element.

Explanation:

it is the purest form

Answer:

b

Explanation:

What name is given to the elements that appear in the right-most column of the periodic
table?
- Alkali metals
- Alkaline earth metals
- Transition metals
- Noble gases
(NOBLE GASES IS ANSWERR)

Answers

Answer:

Noble gases... (You already know...)

Explanation:

The right-most column of the periodic table contains atoms with full electron shells, also known as Noble Gases.

Hope this helped!

Answer:

Noble gases

Explanation:

The six elements listed in the last column of the table (Group 18) of the periodic table are collectively referred to as the noble gases. All of the noble gases have the maximum number of electrons possible in their outer shells (two electrons in helium’s outer shell, and eight electrons for all the others), making them stable.

Determine the molarity of a solution prepared by dissolving 0.198 g of "KHP" (C8H5O4K) in enough water to make 125 mL of solution.
When the solution is found and titrated with aqueous sodium hydroxide, the endpoint is reached after the addition of 27.80 mL of base solution. How many moles of NaOH reacted? What is the concentration of the NaOH?

Answers

Answer:

0.007756M KHP; 0.0009695 moles NaOH reacts; 0.03488M NaOH.

Explanation:

Potassium hydrogen phthalate, KHP, is a salt used as standard to determine concentration of basic solutions as NaOH solutions.

To find molarity of the KHP solution we need to convert mass of KHP to moles and divide this in 125mL = 0.125L:

Moles KHP -Molar mass: 204.22g/mol-:

0.198g * (1mol / 204.22g) = 0.0009695 moles KHP

Molarity:

0.0009695 moles KHP / 0.125L = 0.007756M KHP

NaOH reacts with KHP as follows:

NaOH + KHP → Na⁺ + KP⁻ + H₂O

That means 1 mole of NaOH reacts per mole of KHP, that means moles of NaOH that reacts are = Moles of KHP added:

0.0009695 moles NaOH reacts

In 27.80mL = 0.02780L the NaOH was contained. Molarity is:

0.0009695 moles NaOH / 0.02780L =

0.03488M NaOH

Moles of NaOH added will be "0.034".

According to the question,

→ [tex]Molarity = \frac{Number \ of \ moles}{Volume}[/tex]

By substituting the values, we get

                  [tex]= \frac{0.198}{204}\times \frac{1000}{125}[/tex]

                  [tex]= 0.0077 \ M[/tex]

Let,

The number of moles added be "[tex]M_2[/tex]".

Now,

→            [tex]M_1 V_1 = M_2 V_2[/tex]

→ [tex]0.0077\times 125=M_2\times 27.8[/tex]

→                [tex]M_2 = 0.034 \ moles[/tex]

Thus the above answer is appropriate.

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