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

Oxidation unit test
Please help ASAP!!!

Which statement correctly describes the oxidation number of the manganese atom (Mn) in Mnl2 and MnO2?

O Manganese has an oxidation number of +4 in Mnl2 and +2 in MnO2.
o Manganese has an oxidation number of +2 in Mnl2 and +4 in MnO2.
o Manganese has an oxidation number of +4 in both Mnl2 and MnO2.
Manganese has an oxidation number of +2 in both Mnl2 and MnO2.

Answers

In this case, according to the given information about the oxidation numbers and the compounds given, it turns out possible to figure out the oxidation number of manganese in both MnI2, manganese (II) iodide and MnO2, manganese (IV) oxide, by using the concept of charge balance.

Thus, we can define the oxidation state of iodine and oxygen as -1 and -2, respectively, since the former needs one electron to complete the octet and the latter, two of them.

Next, we can write the following [tex]x[/tex], since manganese has five oxidation states, and it is necessary to calculate the appropriate ones:

[tex]Mn^xI_2^-\\\\Mn ^xO_2^{-2}[/tex]

Next, we multiply each anion's oxidation number by the subscript, to obtain the following:

[tex]Mn^xI_2^-\rightarrow x-2=0;x=+2\\\\Mn ^xO_2^{-2}\rightarrow x-4=0;x=+4[/tex]

Thus, the correct choice is Manganese has an oxidation number of +2 in Mnl2 and +4 in MnO2.

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Environmental scientists collect air samples so they can test the quality of the air. They start with rigid metal containers that are completely empty—the air has been pumped out of them.

What happens to the pressure inside the container and the volume of the container as air enters it?

Answers

Explanation:

filling air inside an empty o2 medal containers, if air is added, the air inside, creates volume inside.

due to heat, weather,... depending on what indoor or outdoor storage said containers r placed in,;

So, I can't give you an answer, due to lack of details..sorry...

which two types of food are homogeneous mixtures
A. mustard
B. mayonnaise
C. tossed salad
D. trail mix

Answers


Answer: It’s most likely Mayonnaise and mustard.
Explanation: It’s definitely mayonnaise because it’s not possible to see the different substances and for mustard it depends on what type. Hope this helps. Good luck :)

Pleeeeasee someone who’s good at chemistry?! 10 grade

ASAP
I’ll give points, just help please

Answers

Answer:

where is the question????????????

Al2(SO3)3
a. Count the number of Sulfur atom
b. How many total atoms are given in the compound
Please helppp

Answers

Answer:

from the words below underline six example of rhetorical patterns

Thin-layer chromatography explain ?????​

Answers

Answer:

Explanation:

Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures. ... After the sample has been applied on the plate, a solvent or solvent mixture (known as the mobile phase) is drawn up the plate via capillary action.

What identifies the number of protons in the nucleus of an atom?

Answers

Answer: Atomic number

Explanation:

I hope this helps you!

Explain how you determine the freezing point of a solution that does not have a well-defined transition in the cooling curve.

Answers

This question is asking for a method for the determination of the freezing point in a solution that does not have a noticeable transition in the cooling curve, which is basically based on a linear fit method.

The first step, would be to understand that when the transition is well-defined as the one on the attached file, we can just identify the temperature by just reading the value on the graph, at the time the slope has a pronounced change. For instance, on the attached, the transition occurs after about 43 seconds and the freezing point will be about 4 °C.

However, when we cannot identify a pronounced change in the slope, it will be necessary to use a linear fit method (such as minimum squares) to figure out the equation for each segmented line having a significantly different slope and then equal them so that we can numerically solve for the intercept.

As an example, imagine two of the segmented lines have the following equations after applying the linear fit method:

[tex]y=-3.5 x + 25\\\\y=-0.52 x + 2[/tex]

First of all, we equal them to find the x-value, in this case the time at which the freezing point takes place:

[tex]-3.5 x + 25=-0.52 x + 2\\\\-3.5 x+0.52 x =2-25\\\\x=\frac{-23}{-2.98}=7.72[/tex]

Next, we plug it in in any of the trendlines to obtain the freezing point as the y-value:

[tex]y=-3.5 (7.72) + 25\\\\y = 1.84[/tex]

This means the freezing point takes place after 7.72 second of cooling and is about 1.84 °C. Now you can replicate it for any not well-defined cooling curve.

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Find five household items that contain ionic compounds. List the following information for each compound: a.name of the product
b. the chemical name of the ionic compound
d.the chemical formula of the ionic compound c. identify the ions present in each compound

Answers

Answer:

D . GOD BLESS .

Explanation:

Suppose you have samples of three unknown solids. Explain how you could use their properties to
determine whether or not they are ionic solids.

Answers

Using melting and boiling temperature, hardness and electric current passing testing.

Ionic solids

Ionic solids are materials that have a strong bond between their ions, thus producing well-defined shapes.

In addition, due to this strong attraction, the boiling and melting temperatures of these materials are very high, in addition to the resistance to breakage presented by them.

Finally, ionic solids are also excellent conductors of electricity.

So, their properties used to determine whether or not they are ionic solids are  melting and boiling temperature, hardness and electric current passing testing.

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For the reaction C + O2 = CO2, if 3 grams of carbon react with the oxygen, how many grams of carbon dioxide are produced?

Answers

3gC x 1molC/12.011gC x 1molCO2/1molC x 44.011gCO2/1molCO2

This gives you 10.99267338g CO2

10 g CO2 if it is one sig fig
11.0 g CO2 if it is two sig fig

Calculate the mass (in grams) of chlorine (Cl2) gas sample which occupies a 2.50 L container at a pressure of 1.22 atm and temperature of 27.8°C?

Answers

Answer:Nothing

Explanation:

The answer is nothing the tempatature isnt matched with the degrees this is false

Convert 1.36x10 to standard form​

Answers

Answer:

13.6 is the correct answer written in standard form.

Explanation:

1.36, move the decimal once to the right to get 13.6

Answer:

13.6

Explanation:

The standard form is 13.6

If 38.6 grams of iron react with an excess of bromine gas, what mass of FeBr2 can form?

Answers

Answer:

›› FeBr2 molecular weight. Molar mass of FeBr2 = 215.653 g/mol. This compound is also known as Iron(II) Bromide. Convert grams FeBr2 to moles or moles FeBr2 to grams. Molecular weight calculation: 55.845 + 79.904*2 ›› Percent composition by element

Explanation:

If 38.6 grams of iron react with an excess of bromine gas, the mass of FeBr2 can form is 149 grams.

What is mass?

Mass is defined as a way to gauge how much matter there is in a substance or thing. The kilogram (kg) is the fundamental SI unit of mass, while lower masses can also be measured in grams (g). Atoms make up everyday matter. A majority of an atom's mass is contained in its nucleus.

Given Fe = 38.6 g.

Fe has a molar mass = 55.845 g/mol.

Given mass/molar mass equals 38.6g/55.845gmol-1, or 0.6912 moles of iron.

The reaction is described as Fe + Br2 FeBr2.

One mole Fe yields 1 mole of FeBr2.

FeBr2 would be produced from 0.6912 moles of Fe.

FeBr2 has a molar mass of 215.65 g/mol.

Moles of FeBr2 x Molar mass of FeBr2

= 215.65 g/mole x 0.6912 mole

= 149.06 g FeBr2 produced is the formula.

Thus, if 38.6 grams of iron react with an excess of bromine gas, the mass of FeBr2 can form is 149 grams.

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Suppose that in an equilibrium mixture of HCl, Cl2, and H2, the concentration of H2 is 1.0 x 10-11 mol-L-1and that of Cl2 is 2.0 x 10-10 mol-L-1. What is the equilibrium molar concentration of HCl at 500 K, given Kc = 4.0 x 1018 for H2(g) +Cl2(g) ⇆ 2HCl(g).

Answers

Considering the definition of Kc, the equilibrium molar concentration of HCl at 500 K is 0.0894 [tex]\frac{mol}{L}[/tex].

The balanced reaction is:

H₂(g) +Cl₂(g) ⇆ 2 HCl(g)

Equilibrium is a state of a reactant system in which no changes are observed as time passes, despite the fact that the substances present continue to react with each other. In other words, reactants become products and products become reactants and they do so at the same rate.

In other words, chemical equilibrium is established when there are two opposite reactions that take place simultaneously at the same speed.

The concentration of reactants and products at equilibrium is related by the equilibrium constant Kc. Its value in a chemical reaction depends on the temperature and the expression of a generic reaction aA + bB ⇄ cC is

[tex]K_{c} =\frac{[C]^{c} x[D]^{d} }{[A]^{a} x[B]^{b} }[/tex]

That is, the constant Kc is equal to the multiplication of the concentrations of the products raised to their stoichiometric coefficients by the multiplication of the concentrations of the reactants also raised to their stoichiometric coefficients.

In this case, the constant Kc can be expressed as:

[tex]K_{c} =\frac{[HCl]^{2} }{[H_{2} ]x[Cl_{2} ] }[/tex]

You know that in an equilibrium mixture of HCl, Cl₂, and H₂:

the concentration of H₂ is 1.0×10⁻¹¹ [tex]\frac{mol}{L}[/tex]the concentration of Cl₂ is 2.0×10⁻¹⁰ [tex]\frac{mol}{L}[/tex]Kc=4×10¹⁸

Replacing in the expression for Kc:

[tex]4x10^{18} =\frac{[HCl]^{2} }{[1x10^{-11} ]x[2x10^{-10} ] }[/tex]

Solving:

[tex]4x10^{18} =\frac{[HCl]^{2} }{2x10^{-21} }[/tex]

[tex]4x10^{18} x 2x10^{-21}=[HCl]^{2}[/tex]

[tex]8x10^{-3} =[HCl]^{2}[/tex]

[tex]\sqrt[2]{8x10^{-3}} =[HCl][/tex]

0.0894 [tex]\frac{mol}{L}[/tex]= [HCl]

Finally, the equilibrium molar concentration of HCl at 500 K is 0.0894 [tex]\frac{mol}{L}[/tex].

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At 298 K, the reaction 2 HF (g) ⇌ H2 (g) + F2 (g) has an equilibrium constant Kc of 8.70x10-3. If the equlibrium concentrations of H2 and F2 gas are both 1.33x10-3 M, determine the initial concentration of HF gas assuming you only started with HF gas and no products initially.

Answers

This problem is describing the equilibrium whereby hydrofluoric acid decomposes to hydrogen and fluorine gases at 298 K whose equilibrium constant is 8.70x10⁻³, the equilibrium concentrations of all the reactants are both 1.33x10⁻³ M and asks for the initial concentration of hydrofluoric acid which turns out to be 2.86x10⁻³ M.

Then, we can write the following equilibrium expression for hydrofluoric acid once the change, [tex]x[/tex], has taken place:

[tex][HF]=[HF]_0-2x[/tex]

Now, since both products are 1.33x10⁻³ M we infer the reaction extent is also 1.33x10⁻³ M, and thus, we can calculate the equilibrium concentration of HF via the law of mass action (equilibrium expression):

[tex]8.70x10^{-3}=\frac{(1.33x10^{-3} M)^2}{[HF]} }[/tex]

[tex][HF]=\frac{(1.33x10^{-3} M)^2}{8.70x10^{-3}} }=2.03x10^{-4}M[/tex]

Finally, the initial concentration of HF is calculated as follows:

[tex][HF]_0=[HF]+2x=2.033x10^{-4}+2*(1.33x10^{-3})=2.86x10^{-3}M[/tex]

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Doing Labs at home

I’m a junior and I’m staying home for this semester and I have to take chemistry and a lot of my work is Labs but I don’t know how to do them since I don’t have the materials at home to do the labs. Someone please help!!!

Answers

Answer:

go get the stuff.

Explanation:

How many atoms are in mercury (I) phospate?
The chemical formula is (Hg2)3(PO4)2

A)11
B)14
C)15
D)16

Answers

Mercury (I) phosphate with the chemical formula  (Hg2)3(PO4)2 has 16 atoms.

Number of Hg atoms = 2x3 = 6Number of P atoms = 2 x 1 = 2Number of O atoms = 4x2 = 8

Sum of all the atoms = 6+2+8

                                   = 16 atoms

More on the number of atoms in a molecule can be found here: https://brainly.com/question/19140379

Determine the molarity for each of the following Solution: 98.0 of phosphoric acids H3PO4 in 1.00L of Solution.​

Answers

The molarity of the solution is 0.01.

Brainliest?

3.00 L of a gas is collected at 35.0 C and 0.93 atm. What is the volume at STP

Answers

2.47L

Hope this helped have a great day :)

WILL GIVE BRAINLEST

Water waves in a small tank are 6.0 cm long. They pass at a given point at a rate of 4.8 waves per second. What is the speed of the wave?

Answers

Answer:,   Correct option is    0.288m/s

Explanation:    

The relationship between the velocity of the wave, its wavelength and frequency is given by the formula

Wavelengthλ=

Frequency(ν)

Speed(v)

,

where, v - velocity of the wave

           λ - wavelength of the wave

          f - frequency of the wave.

In the question it is given that the frequency is 4.8 Hz and the wavelength is 6.0 cm, that is, 0.06 meters.

The velocity of the sound is calculated as follows.

v=f×λ=4.8 Hz×0.06 m=0.288 m/s

Hence, the speed of the water wave is 0.288 m/s.

a. Calculate the change in enthalpy when 20.0 grams of aluminum metal is heated from 298 K to 573 K at constant pressure of 1 atm.
b. Calculate the change in enthalpy when 20.0 grams of metallic lead is taken through the same process. In both cases assume the heat capacity values predicted by equipartition are valid through the temperature range stated.

Answers

Choose all options that apply. Which of the following measurements are equivalent to six feet? a) 72 inches b) 3 meters c) 182.88 cm O d) 1.25 yards
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