State whether the following is an example of a physical or chemical change:! 21. Burning a log: ________________________________! 22. Folding a piece of paper: _________________________! 23. Freezing water: _________________________! 24. Bending a copper wire. _________________________!

Answer:

Explanation:

A crystal of table salt (NaCl) is dissolved in water. Which of the following statements explains why the dissolved salt does not recrystallize as long as the temperature and the amount of water stay constant?

Na+ and Cl- ions lose their charges in the water.

Water molecules surround the Na+ and Cl- ions.

Na+ and Cl- ions leave the water through vaporization.

Water molecules chemically react with the Na+ and Cl- ions.

Your answer: -

Answer: B - Water molecules surround the Na+ and Cl- ions.

Answer:

Magma

Explanation:

Magma is the hot liquid under earths surface

Answer:

Explanation:

Adding sugar

Answer: kg= 0.37

Explanation:

Use the molality formula.

M= m/kg

Due to prokaryote

Explanation:

Answer:

The correct option is 1, since by changing the partial pressures the gas pressures change, the gases go from the zones of higher partial pressure to the zones of lower partial pressure, an example of this is the homeostasis of the human pulmonary alveolus in gas exchange with CO2 and O2.

Explanation:

In the first it increases, in the second the volume is maintained, and in the third reaction it decreases.

Answer:

1. Increase volume.

2. No change.

3. No change.

Explanation:

Hello,

In this case, if we want to shift the reaction rightwards, based on the Le Chatelier's principle we would have to:

1. For this reaction:

[tex]CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g)[/tex]

- Increase the volume or decrease the pressure, since there are more gaseous moles at the products.

2. For this reaction:

[tex]S(s) + 3F_2(g) \rightleftharpoons SF_6(g)[/tex]

- Do nothing since it is not possible to achieve it as we have the same number of gaseous moles at both reactants and products.

3. For this reaction:

[tex]Cl_2(g) + I_2(g)\rightleftharpoons 2ICl(g)[/tex]

- Do nothing since it is not possible to achieve it as we have the same number of gaseous moles at both reactants and products.

Regards.

Answer:

The porosities in dental materials can be of merit and not merit since some dental materials need to be porous in order to reduce their weight and improve their properties and functions, whereas in those (which are the majority) porosities are not Merit, see the properties of the material, the function and can even influence dental rehabilitation.

An example of this is the use of vitreous ionomers, which is a dental material, where when it is spatulated it remains porous, it can give recurrence of infectious caries, since its permeability increases, the best cariogenic microorganisms are filtered and porosity works as a retentive site for these microorganisms that make up the dental biofilm.

In summary, the world of dental materials is very wide, some are resins, other cements, others have metallic claims, etc. To say that the presence of porosity is merit or demerit would be ideal because for some materials this is favorable and for others unfavorable since they are very versatile, with different qualities, different degrees of porosity, different molecules, different coefficients of thermal expansion, some do not set, others do not, some are light-cured, others do not, some withstand more mechanical forces and have more elastic modulus and less porosity, while others do not, and thus with many more variables.

Explanation:

In the manufacture of dental materials, much attention is always paid to what the manufacturer indicates in these indications that come on the reverse side of the material or on a paper inside the material container.

This is important to know, because the manufacturer is the one that indicates the mode of use and working time according to the trademark and the chemical composition of the dental material.

That a dental material in its manufacture is more or less porous, makes its density, weight and volume possibly be affected, there are materials that seek to increase porosity for a certain purpose, while others seek the opposite, depending on the function that is applied, will have more or less pores.

The example we gave above about the vitreous ionomer is an example that indicates that in the case of restorative dental materials where the function is to SEAL the porosity is almost nil, since otherwise it will not seal the cavity that was formed with caries and not the infectious problem would be solved.

On the other hand, in the surgical field of dentistry there are bone grafts or porous macroparticles that are for the purpose of bone replacement, which in order to be integrated need blood vessels that run over these pores, irrigating the area of ​​bone neoformation well, in this case the merit of porosity if necessary and it is essential that they be very porous.

Answer:

[tex]V_2=583.3mL[/tex]

Explanation:

Hello,

In this case, for the given constant amount and pressure of the, we apply the Charles' law which allows us to understand the volume-pressure behavior as a directly proportional relationship:

[tex]\frac{V_1}{T_1} =\frac{V_2}{T_2}[/tex]

Thus, since we need to compute the volume after the temperature increase (which must be expressed in absolute Kelvins), we obtain V2 as:

[tex]V_2=\frac{V_1T_2}{T_1} =\frac{350.0mL*(227+273.15)K}{(27+273.15)K}\\ \\V_2=583.3mL[/tex]

Best regards.

Answer:

.01

Explanation:

H30+=10^-pH

- Hope that helps! Please let me know if you need further explanation.

Answer:

- 7 carbon atoms.

- 14 hydrogen atoms.

- 1 oxygen atom.

Explanation:

Hello,

In this case, for the given compound, heptanone, whose chemical formula is:

[tex]CH_3COCH_2CH_2CH_2CH_2CH_3[/tex]

We can write the molecular formula showing the present atoms of each element:

[tex]C_7H_{14}O[/tex]

In such a way we have:

- 7 carbon atoms.

- 14 hydrogen atoms.

- 1 oxygen atom.

Best regards.

Answer:

C

Explanation:

heat is energy

Answer:

Sulfur Trioxide

Explanation:

Sulfur trioxide is a gas that reacts with liquid water to produce aqueous sulfuric acid,or acid rain.

Answer:

In the case of Mount Pinatubo, the result was a measurable cooling of the Earth's surface for a period of almost two years. Because they scatter and absorb incoming sunlight, aerosol particles exert a cooling effect on the Earth's surface.

Explanation:

Temperature measures the average kinetic energy of particles of the substances. Therefore, the Mt. Pinatubo eruption result in global temperatures dropping almost two degrees.

Temperature is used to measure degree or intensity of heat of a particular substance. Temperature is measured by an instrument called thermometer.

Temperature can be measured in degree Celsius °c, Kelvin k or in Fahrenheit. Temperature is a physical quantity. Heat always flow from higher temperature source to lower temperature source.

We can convert these units of temperature into one another. The relationship between degree Celsius and Fahrenheit can be expressed as:

°C={5(°F-32)}÷9

The Mt. Pinatubo eruption result in global temperatures dropping almost two degrees because they scatter and absorb incoming sunlight, aerosol particles exert a cooling effect on the Earth's temperature.

Therefore, the Mt. Pinatubo eruption result in global temperatures dropping almost two degrees.

To know more about temperature, here:

https://brainly.com/question/13694966

#SPJ6

Answer:

.00352mol/L

Explanation:

molarity (concentration) = number of moles / volume of solvent (in L)

M = .99g / 56.108‬g/mol / .5L

M = .0176mol / .5L

M = .00352mol/L

Answer:

[tex]P_2=50kPa[/tex]

Explanation:

Hello,

In this case, we can apply the Boyle's law in order to understand the pressure-volume relationship as an inversely proportional relationship relating the initial and the final volume:

[tex]P_1V_1=P_2V_2[/tex]

Next, we compute the final pressure P2:

[tex]P_2=\frac{P_1V_1}{V_2}=\frac{100.00kPa*500.0mL}{1000.0mL} \\\\P_2=50kPa[/tex]

Thus we validate, the higher the volume the lower the pressure.

Best regards.

Answer:

Endothermic, positive

Explanation:

Answer:

The mass of zinc sulfide produced is  [tex]M_{ZnS} = 0.76 \ g[/tex]

Explanation:

From the question we are told that

   The mass of zinc is  [tex]m_z = 0.750 \ g[/tex]

    The mass of sulfur is  [tex]m_s = 0.250 \ g[/tex]

The molar mass   of  [tex]Zn_{(s)}[/tex]  is a constant with value  65.39 g /mol

The molar mass of [tex]S_{(s)}[/tex]  is a constant with value  32.01 g/mol

The molar mass of  [tex]ZnS_{(s)}[/tex] is a constant with value 97.46  g/mol

The reaction is  

        [tex]Zn_{(s)} + S_{(s)} ------> ZnS_{(s)}[/tex]

   So from the reaction

       1 mole of  [tex]Zn_{(s)}[/tex] react with 1 mole of  [tex]S_{(s)}[/tex] to produce 1 mole of [tex]ZnS_{(s)}[/tex]

This implies that

65.39 g /mol of  [tex]Zn_{(s)}[/tex] react with 32.01 g/mol of  [tex]S_{(s)}[/tex] to produce   97.46  g/mol  of [tex]ZnS_{(s)}[/tex]

From the values given we can deduce that the limiting reactant is sulfur cause  of the smaller mass

 So  

    0.250 g of  [tex]Zn_{(s)}[/tex] react with 0.250 of  [tex]S_{(s)}[/tex] to produce [tex]x \ g[/tex] of  [tex]ZnS_{(s)}[/tex]

So

      [tex]x = \frac{97.46 * 0.250}{32.01}[/tex]

       [tex]x = 0.76 \ g[/tex]

Thus the mass of the mass of zinc sulfide produced is

    [tex]M_{ZnS} = 0.76 \ g[/tex]

Answer:

See explanation below

Explanation:

To do aflow diagram for extraction of these two components of a sample, we need to analize both reagents so we can make a great diagram and separate both reagents.

First, let's see the acid. The 2-chlorobenzoic acid is a relativel strong acid, so, in order to separate this from a sample we need to use a base to do so. However, it's very important the use of the base here, we cannot use any base to do it, for the main reason that the sample has other component, and this component may react too with the base and the separation will not be succesfull. So, as the chlorobenzoic acid is a relatively strong acid, if we use a strong base such as NaOH, this will react with the acid, but it will also react with the 1,4-dichlorobenzene forming a Sn2 product and a salt like this.

C₆H₄Cl₂ + NaOH ---------> C₆H₅OCl + NaCl

This is the reason which we cannot use NaOH, because it's a strong base that may react with other compounds in the sample.

To solve this, we can use a weak base such as NaHCO₃. This weak base has the strength enough to react with the benzoic acid, but not strong enough to react with the dichlorobenzene.

So, the first step is dissolve the sample in an organic solvent like ether. The next step is mixing the sample with NaHCO₃. This will cause the layer to divide into two layers. One aqueous layer that will have the product of the acid with the base, and an organic layer with the dichlobenzene. Afterward, we just need to use a strong acid like HCl, but dilluted in the aqueous layer to regenerate the acid, and in the organic layer, just heat the solution til the whole solvent evaporates completely.

The flow diagram is below in the attached picture.

Answer:

respiration

Explanation:

Plants give out carbon dioxide not only at night but during the day too. It happens because of the process of respiration in which plants take in oxygen and give out carbon dioxide. As soon as the sun rises another process called photosynthesis starts, in which carbon dioxide is taken in and oxygen is given out.

Plants use photosynthesis to capture carbon dioxide and then release half of it into the atmosphere through respiration. Plants also release oxygen into the atmosphere through photosynthesis

Answer:

26 mol

Explanation:

Step 1: Write the balanced equation

4 FeCl₃ + 3 O₂ ⇒ 2 Fe₂O₃ + 3 Cl₂

Step 2: Determine the appropriate molar ratio

The molar ratio of FeCl₃ to O₂ is 4:3.

Step 3: Use the determined molar ratio to calculate the moles of oxygen required to completely react with 35 moles of ferric chloride

[tex]35molFeCl_3 \times \frac{3molO_2}{4molFeCl_3} = 26molO_2[/tex]

Answer:

[tex]n_{O_2}=26.25molO_2[/tex]

Explanation:

Hello,

In this case, given the reaction:

[tex]4FeCl_3 + 3O_2 \rightarrow 2Fe_2O_3 + 6Cl_2[/tex]

Since oxygen and iron (III) chloride are in a 4:3 molar ratio, he required moles of oxygen to completely react with 35 moles of iron (III) chloride result:

[tex]n_{O_2}=35molFeCl_3*\frac{3molO_2}{4molFeCl_3} \\\\n_{O_2}=26.25molO_2[/tex]

Best regards.

Answer:

C. cooler than both the crust and the core

Explanation:

It is observed that at the mantle, temperatures range from estimatedly 200 °C (392 °F) around the upper boundary with the crust to approximately 4,000 °C (7,230 °F) at the core-mantle boundary.

So we can say the mantle is cooler than both the crust and the core.

Answer:

400 kPa

Explanation:

Please see the step-by-step solution in the picture attached below.

Hope this answer can help you. Have a nice day!

Answer:

400 kPa

The answer is right since its from ck12

Answer:

2 HCl

Explanation:

Please kindly check attachment for the step by step solution of the given problem.

Explanation:

MnO4−+ SO32− → Mn2++ SO42−

Splitting into half equations;

MnO4−  → Mn2+

SO32− → SO42−

Balancing the electrons;

2 MnO4−  + 10 e- → 2Mn2+

5SO32− → 5SO42− + 10 e-

In an acidic medium, it becomes;

2 MnO4−  +  8 H+ → 2 Mn2+ + 4 H2O

5 SO32−  + H2O → 5 SO42−  +  2 H+

Final equation is;

2 MnO4- + 5 SO32- + 6 H+ → 2 (Mn)2+ + 5 SO42- + 3 H2O

Coefficient of H+ = 6

Coefficient of H2O = 3

Coefficient of MnO4- = 2

Coefficient of SO32- = 5

Coefficient of (Mn)2+- = 2

Coefficient of SO42- = 5

Answer:

[tex]5SO_3^{2-}+2MnO_4^{-}+6H^+ \rightarrow 5SO_4^{2-}+ 2Mn^{2+}+3H_2O[/tex]

Explanation:

Hello,

In this case, given the reaction:

[tex]MnO_4^{-}+ SO_3^{2-} \rightarrow Mn^{2+}+ SO_4^{2-}[/tex]

We first identify the oxidation state of both manganese and sulfur at each side:

[tex]Mn^{7+}O_4^{-}+ S^{4+}O_3^{2-} \rightarrow Mn^{2+}+ S^{6+}O_4^{2-}[/tex]

So we have the oxidation and reduction half-reactions below, including the addition of water and hydronium as it is in acidic media:

[tex]S^{4+}O_3^{2-}+H_2O \rightarrow S^{6+}O_4^{2-}+2H^++2e^-[/tex]

[tex]Mn^{7+}O_4^{-}+8H^++5e^- \rightarrow Mn^{2+}+4H_2O[/tex]

Next, we exchange the transferred electrons:

[tex]5*(S^{4+}O_3^{2-}+H_2O \rightarrow S^{6+}O_4^{2-}+2H^++2e^-)\\2*(Mn^{7+}O_4^{-}+8H^++5e^- \rightarrow Mn^{2+}+4H_2O)\\\\5S^{4+}O_3^{2-}+5H_2O \rightarrow 5S^{6+}O_4^{2-}+10H^++10e^-\\2Mn^{7+}O_4^{-}+16H^++10e^- \rightarrow 2Mn^{2+}+8H_2O[/tex]

Then we add the resulting half-reactions and simplify the transferred electrons:

[tex]5S^{4+}O_3^{2-}+5H_2O+2Mn^{7+}O_4^{-}+16H^+ \rightarrow 5S^{6+}O_4^{2-}+10H^++ 2Mn^{2+}+8H_2O[/tex]

We rearrange the terms in order to simplify water and hydronium molecules:

[tex]5S^{4+}O_3^{2-}+2Mn^{7+}O_4^{-}+16H^+-10H^+ \rightarrow 5S^{6+}O_4^{2-}+ 2Mn^{2+}+8H_2O-5H_2O\\\\5S^{4+}O_3^{2-}+2Mn^{7+}O_4^{-}+6H^+ \rightarrow 5S^{6+}O_4^{2-}+ 2Mn^{2+}+3H_2O[/tex]

Finally we write the balanced reaction in acidic media:

[tex]5SO_3^{2-}+2MnO_4^{-}+6H^+ \rightarrow 5SO_4^{2-}+ 2Mn^{2+}+3H_2O[/tex]

Best regards.

hard because it has calcium and magnesium

Answer:

400 mL

Explanation:

Boyle's Law: [tex]P_1*V_1 = P_2*V_2[/tex]

Let x = the resulting volume

350 (200) = 700 (x)

x = 400 mL