What kind of change forms a new substance?

A physical change

Answer:

3.6 x 10²²molecules

Explanation:

Given parameters:

Mass of ethane gas  = 1.8g

Unknown:

number of molecules of ethane gas = ?

Solution:

To solve this problem, we first find the number of moles of ethane gas.

  Molar mass of ethane, C₂H₆  = 2(12) + 6(1) = 30g/mol

 Number of moles  = [tex]\frac{mass}{molar mass}[/tex]

Insert the parameters and solve;

  Number of moles  = [tex]\frac{1.8}{30}[/tex]   = 0.06mole

 1 mole of a substance contains 6.02 x 10²³ molecules

 0.06mole of ethane will contain 0.06 x 6.02 x 10²³  = 3.6 x 10²²molecules

Answer:

Elements

Explanation:

I did a quiz I'm 11 hope it helps\

Mol of Kr gas = 1.244

In general, the gas equation can be written  

where  

P = pressure, atm  

V = volume, liter  

n = number of moles  

R = gas constant = 0.08205 L.atm / mol K  

T = temperature, Kelvin  

P=1.31 atm

V=23.3 L

T=26+273=299 K

mol of sample :

[tex]\tt n=\dfrac{PV}{RT}=\dfrac{1.31\times 23.3}{0.08205\times 299}=1.244[/tex]

Answer:

a. K = [H+][NO2-]/[HNO2]

Explanation:

The computation of the expression of the equilibrium constant is shown below:

Given that the weak acid is HNO_2 that exist in the solution that aqueous

The dissociation equation of [tex]HNO_2[/tex]

[tex]HNO_2(aq) \rightarrow NO_{2}^{-} (aq) + H^{+}(aq)[/tex]

Now

Acidionization constant i.e.

[tex]k_a = \frac{[NO_{2}^{-}][H^{+}]}{HNO_{2}}[/tex]

Therefore the correct option is a.

Hence, the same is to be considered

Answer:

One sigma bond and two pi bonds.

Explanation:

Triple covalent bonds between two atoms are created when they share three electron pairs. Three dashes connecting the atoms signify a triple bond. Pnictogen or the nitrogen family of atoms are those having triple valency. The correct option is C.

Two pi bonds and one sigma bond make up a triple bond. One sigma bond and one pi bond make up a double bond. Sigma bonds are usually made up of one atom. A single bond is described as a two-valence electron chemical bond between two atoms.

Covalent bonds with overlapping atomic orbitals fall under the categories of sigma and pi bonds. While pi bonds are created by the lateral overlapping of two atomic orbitals, sigma bonds are created by the head-to-head overlapping of atomic orbitals.

Thus the correct option is C.

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Answer:

2.938 mol Pb(NO₃)₄

Explanation:

Step 1: Given data

Step 2: Write the balanced equation

4 (NH₄)₃PO₄ + 3 Pb(NO₃)₄ = Pb₃(PO₄)₄ + 12 NH₄NO₃

Step 3: Calculate the number of moles of Pb(NO₃)₄required to produce 11.75 moles of NH₄NO₃

The molar ratio of Pb(NO₃)₄ to NH₄NO₃ is 3:12.

11.75 mol NH₄NO₃ × (3 mol Pb(NO₃)₄/12 mol NH₄NO₃) = 2.938 mol Pb(NO₃)₄

Answer:

Ammonia is a weak electrolyte, weak base.

Option e.

Explanation:

Ammonia can take a proton from water to make ammonium.

It is a base, because it takes proton.

When a compound can take protons, we know that is base, according to Bronsted Lowry theory.

We can't describe ammonia as a base, according to Arrhenius, but we know it is base according to Lewis, because the N from the ammonia can be a donor of its electron pair.

It is weak because an small amount of ammonia, can react to produce ammonium, between the protons of water. This is the equilibrium, where the ammonia is considered as the conjugate strong acid of ammonia.

NH₃ +  H₂O  ⇄  NH₄⁺  +  OH⁻     Kb

All the amines are considered as weak bases, because they look like ammonia, where the H of NH₃ are replaced by others chains.

------NH₂

-----NH-----

Answer:

The uncertainty of inventiveness and futuristic ideas usually deal with science and technology. ... This is usually linked to futuristic ideas, which may not fit in today's society, but which impose improvements, or not, for societies in the future.

Answer:

Volume of methanol present in solution = less than 3 ml

Explanation:

Given:

Volume of solution = 750 ml

Find:

Volume of methanol present in solution

Computation:

Volume of methanol present in solution = Volume of solution x 0.4%

Volume of methanol present in solution = 750 ml x 0.4%

Volume of methanol present in solution = 3 ml

Volume of methanol present in solution = less than 3 ml

The amount of methanol present in the 750 mL solution is 3 mL

From the question given above, the following data were obtained:

Percentage of methanol = 0.4%

Volume of solution = 750 mL

The volume of methanol present in the 750 mL of solution can be obtained as follow:

Volume = Percent × Volume of solution

Volume of methanol = 0.4% × 750

Volume of methanol = 0.004 × 750

Thus, the amount of methanol present in the 750 mL solution is 3 mL

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Answer:

A.

Explanation:

hope this helped sorry if its wrong!

Answer:

The solubility of calcium phosphate is

2.21x10−4g/L.

Explanation:

Answer:

Explanation:

2N₂O(g) → 2N₂(g) + O₂(g)

molecular weight of N₂O = 44

∆Hº = –166.7 kJ/mol

44 g of N₂O decomposes to give 166.7 kJ of heat

2.25 g of N₂O decomposes to give 166.7 x 2.25 / 44 kJ of heat

= 8.51 kJ of heat .

Answer:

try a dude ummm yes ok yeah

Answer:

1.47 x 10⁻¹⁹J

Explanation:

Given parameters;

Frequency of wave  = 2.22 x 10¹⁴/s

Unknown:

Energy of the photon = ?

Solution:

The energy of a photon can be mathematically derived using the expression below;

        E = hf

  E is the energy

 h is the Planck's constant = 6.63 x 10⁻³⁴m²kg/s

 f is the frequency  

Insert the parameters and solve;

 E = 6.63 x 10⁻³⁴m²kg/s x  2.22 x 10¹⁴/s  

 E = 14.7 x 10⁻²⁰J or 1.47 x 10⁻¹⁹J

Answer:

* [tex]HI (aq) +NaOH (aq) \rightarrow NaI(aq)+H_2O(l)[/tex]

* [tex]H_2CO_3 (aq) + Sr(OH)_2\rightarrow SrCO_3(s)+2H_2O(l)[/tex]

* [tex]Ca(OH)_2 (s) +H_2SO_4 (aq)\rightarrow CaSO_4(aq)+2H_2O(l)[/tex]

Explanation:

Hello!

In this case, since neutralization chemical reactions are carried out when an acid and a base react to produce a salt and water, for the first reaction, HI (aq) and NaOH (aq), we can write:

[tex]HI (aq) +NaOH (aq) \rightarrow NaI(aq)+H_2O(l)[/tex]

Whereas the salt, sodium iodide remains aqueous and water liquid. Next, when carbonic acid and strontium hydroxide react, strontium carbonate as the salt precipitates out and water is also produced:

[tex]H_2CO_3 (aq) + Sr(OH)_2\rightarrow SrCO_3(s)+2H_2O(l)[/tex]

Finally, when calcium hydroxide and sulfuric acid react, the compound calcium sulfate as the salt and water are produced as shown below:

[tex]Ca(OH)_2 (s) +H_2SO_4 (aq)\rightarrow CaSO_4(aq)+2H_2O(l)[/tex]

Best regards!

Answer:

True,

Explanation:

doesn't have ends like chromosomes of eukaryotic organisms

so all bacteria contains chromosomes yes, 100%

can i have brainliest i need 2 more to get a new rank tysm

Answer: 90

Explanation: Sugar dissolves faster in hot water than it does in cold water because hot water has more energy than cold water. When water is heated, the molecules gain energy and, thus, move faster. As they move faster, they come into contact with the sugar more often, causing it to dissolve faster.

Answer:

90 c

Explanation:

The sugar dissolve in the hottest bc of the heat it will melt in with the water i an pretty sure

Answer:

pOH = 4

Explanation:

NaOH is a strong base which means that it dissociates completely in water. It will break apart into Na⁺ and OH⁻ ions.

NaOH ⇒ Na⁺ + OH⁻

Because NaOH dissociates completely into its respective ions in water, the moles of NaOH is equal to the moles of hydroxide ions. So, [OH⁻] = 0.0001 M.

Now to find the pOH, use the formula pOH = -log[OH⁻].

pOH = -log[OH⁻]

= -log(0.0001)

= 4

The pOH of the solution is 4.

Hope that helps.

The element you are looking for is Scandium, the 4th element in the third group.

Answer:

unconsolidated material that contains nutrient matter and weathered rock

Explanation:

Earth's crust is made up of many layers. The top is soil, which provides the most nutrients for plants, like hummus( The organic nutrient for soil, form from the decaying of plants and animals)

The soil gets its texture from the bedrock, the bottom layer, which weathers, and goes into the soil.

-kiniwih426

Answer:

3HCl(aq)+Al(OH)3(s)=AlCl3(aq)+3H2O(l)

Explanation:

This is a double replacement reaction.

Step One: Write down the compound from the name.

Aluminum Hydroxide Al(OH)3

Hydrochloric Acid HCL

Step Two: Perform the double replacement reaction.

AB+CD=AD+CB

Step Three: Balance the equation

Final step: Write in physical states.

The physical state will either be (aq), (s), (l) or (g).

Answer:

24.5g

Explanation:

Given parameters:

Mass of oxygen gas = 21.8g

Unknown:

Mass of water  = ?

Solution:

This problem deals with the decomposition of water;

    Reaction equation;

                  2H₂O →  2H₂  +  O₂

2 mole of water will produce 1 mole of oxygen gas

First find the number of mole of the oxygen gas given;

          Number of moles  = [tex]\frac{mass}{molar mass}[/tex]

    molar mass of O₂   = 2(16) = 32g/mol

  Number of moles of O₂  = [tex]\frac{21.8}{32}[/tex]   = 0.68moles

    1 mole of oxygen gas will be produced from 2 mole of water

     0.68moles of oxygen gas will be produce from  0.68 x 2 moles of water;   = 1.36moles of water

Mass of water = number of moles x molar mass

  Molar mass of water = 2(1) + 16  = 18g/mol

Mass of water  = 1.36 x 18  = 24.5g

protons

there aint rlly an explanation tbh

Answer:

Nucleons

The mass number of a nucleus is the number of protons and neutrons called the nucleons! Nucleons are the sum of protons and neutrons present in the nucleus of an atom.

Answer:

A & B

Explanation:

Done the Quiz

The empirical formula for a compound : ZnO

The empirical formula is the smallest comparison of atoms of compound =mole ratio of the components

The principle of determining empirical formula

Determine the mass ratio of the constituent elements of the compound.  

Determine the mole ratio by by dividing the percentage by the atomic mass

Percentage Oxygen :

100\%-80.2%=19.8\%

mol ratio for Zn : O =

[tex]\tt \dfrac{80.2}{65.38}\div \dfrac{19.8}{16}\\\\1.227\div 1.238\rightarrow divide~by~smallest(1.227)\\\\1\div 1[/tex]

Answer:

inertia

Explanation:

Given that :

Reaction equation ; [tex]HB_{r} + KOH ---> KBr + H_{2}O[/tex]

A) and B)  Determine the Initial pH before addition of titrant

First step : compute the value of pOH

pOH = - log ( [OH⁻])

        = -log ( 0.320 ) = 0.50

∴ Initial pH before the titrant is added = 14 - pOH

                                                               = 14 - 0.5 = 13.5

C ) Determine the pH of solution after 5 mL titrant is added

First step : determine the reacting moles of each substance

n kOH = 0.025 mL * 0.320 mol/L = 0.00800 mol

n HBr = 0.005 * 0.750 mol/L = 0.00375 mol

next step : compute the value of the concentration of OH⁻ in final solution

n kOH ( remaining ) = 0.00800 - 0.00375 = 0.00425 mol

final solution = 25.00 mL + 5.00 mL = 30.00 mL

∴ The value of the concentration of [ OH⁻] in 30.00 mL

  = [ OH⁻] = ( 0.0042 mol / 0.0300 mL )

                = 0.142 M

 hence pOH = - log (0.142) = 0.849

Final step; The pH of the solution after 5 mL of titrant is added

= 14 - pOH

= 14 - 0.849 = 13.15

Hence we can conclude that the initial pH before titrant was added is 13.50 and the pH after is as listed above.

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Answer:

A) species

Explanation:

Of the Linnaeus's groupings, organisms at the species level are the most closely related to one another.

The species level is the lowest level of classification in the Linnaean system of classification.

Answer:

C. Speed

Explanation:

Density differences in different materials are able to change the speed of a wave.

Answer:

Speed

Explanation:

The speed or mass of something can totally change the direction of the wave