A chemical formula is an expression used to represent

single atoms with more than one electron

Answer:

Explanation:

Bohr’s model could only explain the spectra of single atoms with one electron.

Bohr’s model:

It shows that the negatively charged electrons orbit the positively charged nucleus in a fixed circular path.

Therefore, Bohr’s model could only explain the spectra of single atoms with one electron.

To know more about Bohr’s model:

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Answer:

Explanation:

The term organic matter refers to the matter in the living organisms. Nowadays, organic compounds, the object of organic chemistry, are the compounds that contain carbon except carbon oxides, carbides and carbonates (which are considered inorganic compounds).

Organic compounds form a vast  variety of vital compounds based on the versatility of carbon atoms.

Carbon atoms have four valence electrons which can form a variety of single, double, and triple bonds with it self, to form long chains.

Carbon atoms can also form bonds with other elements like, hydrogen, oxygen, nitrogen, halogens, among others, to form different kind of compounds: alkanes, alkenes, alkynes, alcohols, aldehydes, esters, eters, amines, amides, polymers, among others.

Thus, organic compounds form a vast subject of study based on the  special chemical properties of carbon.

Contrast:

Solutions are clear, transparent, and homogeneous.

Suspensions are cloudy, heterogeneous, and at least two substances are visable

Compare: one similarity is that neither of their particles settle.

Answer:

The Substance Has Changed and Has Become Something Else

Explanation:

When a chemical reaction occurs it has a few characteristics, for example burning. The substance, paper, becomes something else, ash. The ash can no longer be turned back into paper. Another example is rust, once and object is rust due to oxidation it can no longer return back. A physical reaction on the other hand can be reversed, like freezing. To spot chemical change look for color changing, gas production, a change in temperature, or if you see any light.

Answer:

Low melting point.

Explanation:

We cannot link the pH of a substance from it bonds directly.

Ionic compounds have strong ionic bonds but we cannot say that they will have high or low pH.

High conductivity is a feature of ionic compounds generally (also metals)

low melting point means the bonds are weak so they can be weak covalent bonds.

Low flammability is not related to bonding.

Answer:

2, the acid is H₂X.

Explanation:

∴ (nMV) of NaOH = (nMV) for HnX.

where, n is the no. of producible H⁺ or OH⁻ of the acid or base, respectively.

M is the molarity of the acid or base.

V is the volume of the acid or base.

n = 1, M = 0.4 M, V = 0.6 L.

n = ???, M = 0.3 M, V = 0.4 L.

∴ n for HnX = (nMV) of NaOH / (MV) for HnX = (1)(0.4 M)(0.6 L)/(0.3 M)(0.4 L) = 2.

∴ the acid is H₂X.

The value of n in HnX is 1, making it a monoprotic acid.

This question is related to acid-base titration. In this case, 0.400 L of a 0.300 M HnX is being titrated with 0.600 L of 0.400 M sodium hydroxide (NaOH) to the equivalence point.

From the given information, we can use the concept of stoichiometry to determine the value of n in HnX. Since NaOH is a strong base and reacts with HnX in a 1:1 ratio, we can set up the following equation:

0.400 L x 0.300 M HnX = 0.600 L x 0.400 M NaOH

Solving for n, we find that n = 1. Therefore, HnX is a monoprotic acid.

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The compounds ranked from the slowest to fastest rate of hydration are 3,3-dimethylbutan-2-one, 3-methylbutan-2-one, butan-2-one, propanal, and formaldehyde. Steric hindrance plays a crucial role in determining the reactivity of carbonyl compounds towards nucleophilic hydration reactions.

The rate of hydration for carbonyl compounds, such as aldehydes and ketones, is influenced by their reactivity towards nucleophilic attack. This reactivity is mainly determined by the electron-withdrawing or -donating nature of substituents on the carbonyl carbon and steric effects.

In this context, we can rank the compounds based on their rates of hydration:

Formaldehyde (CH2O): Formaldehyde is the simplest aldehyde, and its high reactivity is attributed to the lack of steric hindrance. The absence of bulky substituents allows nucleophiles to approach the carbonyl carbon easily, resulting in a fast rate of hydration.

Propanal (CH3CH2CHO): Propanal has a moderately reactive carbonyl group. The presence of a linear alkyl chain provides some steric hindrance compared to formaldehyde, slowing down the hydration rate slightly.

Butan-2-one (CH3COCH2CH3): Butan-2-one, also known as methyl ethyl ketone, has a more substituted carbonyl carbon due to the ethyl group. This increased steric hindrance results in a slower rate of hydration compared to propanal.

3-Methylbutan-2-one (CH3COCH(CH3)2): The presence of a branched methyl group in the 3-position introduces additional steric hindrance. This bulky substituent slows down the nucleophilic attack, leading to a slower rate of hydration.

3,3-Dimethylbutan-2-one (CH3COCH(CH3)2CH3): This compound has the highest steric hindrance among the given options due to two methyl groups in the 3-position. The bulkiness significantly hinders the approach of nucleophiles, resulting in the slowest rate of hydration.

Hydration rates are influenced by steric hindrance and the reactivity of the molecule. Formaldehyde is the fastest to hydrate due to minimal steric hindrance and high reactivity, while 3,3-dimethylbutan-2-one, having the most steric hindrance, is the slowest.

When ranking the compounds from slowest to fastest rate of hydration, we need to consider the factors that affect hydration rates such as structure, size, and functional group. Hydration involves the addition of water to the compound, and this process is generally faster for molecules that can better stabilize the transition state. Formaldehyde is highly reactive and can form a hydrate readily, despite its small size, due to its high reactivity and the lack of steric hindrance. For ketones, increased steric hindrance and a decrease in polarization of the carbonyl group result in slower hydration rates.

Based on these considerations, the ranking from slowest to fastest rate of hydration for the given compounds would be: 3,3-dimethylbutan-2-one (most steric hindrance and least reactive), 3-methylbutan-2-one, butan-2-one, propanal, and formaldehyde (least steric hindrance and most reactive).

Answer:

The answer is KINETIC energy

Explanation:

The baseball is moving and Kinetic energy correlates to movement.

Answer:

Explanation:

Condensing steam into liquid water is the reverse process of vaporizing liquid water into steam.

The heat or enthalpy of vaporization, also called latent heat of vaporization, of liquid water is the amount of heat that the water absorbs when changes from liquid state to steam (vapour) at certain pressure and it is a constant at every pressure.

The symbol of the latent heat of vaporization is Hvap or ΔHvap.

Thus, being being condensing the reverse process of vaporization, the heat of condensing will be the same magnitude but in reverse direction, i.e. the heat will be released instead of absorbed, and the engineer will have to use the negative of the latent heat of vaporization: - Hvap or - ΔHvap.

Answer:

b) -hvap

Explanation:

edge 2021

Answer:

a) 0.38 mol.

b) 0.38 mol.

c) 26.94 g.

Explanation:

2KI(aq) + Cl₂(g) → 2KCl(aq) + I₂(g),

It is clear that 2 mol of KI react with 1 mol of Cl₂ to produce 2 mol of KCl and 1 mol of I₂.

a) How many moles of I₂ are produced?  

It is known that every 1.0 mol of any gas occupies 22.4 L at STP conditions.

Using cross multiplication:

1 mol of I₂ occupies → 22.4 L, at STP.

??? mol of I₂ occupies → 8.5 L, at STP.

∴ The no. of moles of I₂ produced = (1 mol)(8.5 mol)/(22.4 L) = 0.38 mol.

b) How many moles of Cl₂ are used?

Using cross multiplication:

1 mol of Cl₂ produces → 1 mol of I₂, from stichiometry.

∴ 0.38 mol of Cl₂ produces → 0.38 mol of I₂.

So, the no. of moles of Cl₂ are used = 0.38 mol.

c) How many grams of Cl₂(g) are used?

∴ The "no. of grams" of Cl₂(g) are used = (no. of moles of Cl₂)(molar mass of Cl₂) = (0.38 mol)(70.9 g/mol) = 26.94 g.

Answer:

Na

Explanation:

Cl, S and Na are all in the same period.

The further left an element is in a row of the periodic table, the larger its atomic radius.

Answer:

Na

Explanation:

Answer:

B. 78 °C.

Explanation:

Q = m.c.ΔT,

where, Q is the amount of heat released from water (Q = - 1500 J).

m is the mass of water (m = 30.0 g).

c is the specific heat capacity of water (c = 4.18 J/g.°C).

ΔT is the difference between the initial and final temperature (ΔT = final T - initial T = final T - 90.0 °C).

∴ (- 1500 J) = (30.0 g)(4.18 J/g.°C)(final T - 90.0 °C)

∴ (final T - 90.0 °C) = (- 1500 J)/(30.0 g)(4.18 J/g.°C) = - 11.96°C.

∴ final T = 90.0 °C - 11.96°C = 78.04°C ≅ 78 °C.

So, the right choice is: B. 78 °C.

Answer:

78 °C

Explanation:

I took the test and got it correct. hope this helps

Answer:

Explanation:

Air is a mixture of gases (mainly oxygen and nitrogen, but also carbon dioxide, water vapor, and others in minimum amount).

The pressure of the gases is the product of the collisions of the air molecules with the surface of the objects. Since the molecules of gases are in constant, rapid random motion, they are constantly (you may say continously) colliding with the surfaces of the objects in all directions. That explain, why the air exertes pressure in all directions.

There are many experiments that you can perform to show this phenomenum.

You can perform this experiment, for example:

What will you observe?

Why does that happen?

Since the pressure is exerted in all the directions, the bottle or can collapse.

Answer:

I think its The reaction reaches equilibrium and the products stop being formed.

Answer:

Option C is true.

Explanation:

We are given that some reactions appear to stop before all the reactants are converted to products

We have to find the best explanation in given option  why some reactions appear to stop before all the reactant are converted to products.

Reverse reaction : It is defined as the reaction in which reactants and products exist in a state of equilibrium.

Rate of froward reaction is equal to rate of backward reaction when the reaction is in equilibrium condition.

The reaction is not actually stop but it appear that the reaction to stop before all the reactants are concerted to products.

Hence, the reversible reaction occurs at the same rate occurs at the rate is best explanation for some reaction appear to stop before all the reactants are converted to products.

Option C is true.

Answer:

[tex]\boxed{\text{H$_{3}$O$^{+}$ + OH$^{-} \longrightarrow$ 2H$_{2}$O}}[/tex]

Explanation:

1. "Molecular" equation

[tex]\rm Ca(OH)$_{2}$ + 2H$_{3}$O$^{+} \longrightarrow \,$ Ca$^{2+}$ + 4H$_{2}$O[/tex]

2. Ionic equation

[tex]\rm \textbf{Ca}$^{2+}$ + 2OH$^{-}$ + 2H$_{3}$O$^{+}$ \longrightarrow \textbf{Ca}$^{2+}$ + 4H$_{2}$O[/tex]

3. Net ionic equation

Cancel all ions that appear on both sides of the reaction arrow (in boldface).

[tex]\rm 2OH$^{-}$ + 2H$_{3}$O$^{+} \longrightarrow$ 4H$_{2}$O[/tex]

Divide every coefficient by 2.

[tex]\rm OH$^{-}$ + H$_{3}$O$^{+} \longrightarrow$ 2H$_{2}$O[/tex]

Hello There!

On the periodic table, fluorine is the most electronegative element. On the periodic table, its symbol is F.

ATOMIC NUMBER "9"

ATOMIC MASS "18.998404" (19)

NEUTRONS "19-10=9" (9)

PROTONS "9"

ELECTRONS "9"

Fluorine is corrosive and a pale yellow gas.

Answer:

1) a) [OH⁻] = 0.025 M.

  b) pH = 12.4.

  c) The solution is basic.

2) a) [OH⁻] = 1.66 x 10⁻⁸ M.

  b) pH = 6.22.

   c) The solution is acidic.

3) a) [H⁺] = 3.16 x 10⁻⁴ M.

   b) pH = 3.5.

    c) The solution is acidic.

4) a) [H⁺] = 3.16 x 10⁻⁷ M.

   b) pH = 6.5.

    c) The solution is acidic.

Explanation:

1) In saturated lime water, [H⁺] = 3.98 x 10⁻¹³ M.

a) Find [OH⁻]

∵ [H⁺][OH⁻] = 10⁻¹⁴.

∴ [OH⁻] = 10⁻¹⁴/[H⁺] = 10⁻¹⁴/(3.98 x 10⁻¹³ M) = 0.025 M.

b) What is the pH?

∵ pH = - log[H⁺].

[H⁺] = 3.98 x 10⁻¹³ M.

∴ pH = - log(3.98 x 10⁻¹³ M) = 12.4.

c) Is the solution acidic, basic, or neutral?

pH is a scale from 0 to 14.

∵ pH = 12.4 > 7.

∴ The solution is basic.

2) In butter, [H⁺] = 6.0 x 10⁻⁷ M.

a) Find [OH⁻]

∵ [H⁺][OH⁻] = 10⁻¹⁴.

∴ [OH⁻] = 10⁻¹⁴/[H⁺] = 10⁻¹⁴/(6.0 x 10⁻⁷ M) = 1.66 x 10⁻⁸ M.

b) What is the pH?

∵ pH = - log[H⁺].

[H⁺] = 6.0 x 10⁻⁷ M.

∴ pH = - log(6.0 x 10⁻⁷ M) = 6.22.

c) Is the solution acidic, basic, or neutral?

pH is a scale from 0 to 14.

∵ pH = 6.22 < 7.

∴ The solution is acidic.

3) In peaches, [OH⁻] = 3.16 x 10⁻¹¹ M

a) Find [H⁺]

∵ [H⁺][OH⁻] = 10⁻¹⁴.

∴ [H⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(3.16 x 10⁻¹¹ M) = 3.16 x 10⁻⁴ M.

b) What is the pH?

∵ pH = - log[H⁺].

[H⁺] = 3.16 x 10⁻⁴ M.

∴ pH = - log(3.16 x 10⁻⁴ M) = 3.5.

c) Is the solution acidic, basic, or neutral?

pH is a scale from 0 to 14.

∵ pH = 3.5 < 7.

∴ The solution is acidic.

4) During the course of the day, human saliva varies between being acidic and basic. If [OH⁻] = 3.16 x 10⁻⁸ M,

a) Find [H⁺]

∵ [H⁺][OH⁻] = 10⁻¹⁴.

∴ [H⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(3.16 x 10⁻⁸ M) = 3.16 x 10⁻⁷ M.

b) What is the pH?

∵ pH = - log[H⁺].

[H⁺] = 3.16 x 10⁻⁷ M.

∴ pH = - log(3.16 x 10⁻⁷ M) = 6.5.

c) Is the solution acidic, basic, or neutral?

pH is a scale from 0 to 14.

∵ pH = 6.5 < 7.

∴ The solution is acidic.

Answer:

The answer to your question is False.

Explanation:

An insoluble substance cannot dissolve

Final answer:

The statement is false; insoluble substances by definition do not readily dissolve in solvents, and solubility depends on the 'like dissolves like' principle where substances dissolve in solvents with similar intermolecular forces.

Explanation:

The statement that insoluble substances can dissolve in all solvents is false. An insoluble substance is defined as a solute that does not dissolve in a solvent. While it is true that no solid is perfectly insoluble and most have some small level of solubility in a solvent, the term 'insoluble' is used to describe substances that do not dissolve to any significant extent. The solubility of a substance largely depends on the similarity in intermolecular forces between the solute and the solvent, which is summarized by the rule 'like dissolves like'.

Nonpolar substances are generally soluble in nonpolar solvents, whereas polar and ionic substances are more likely to dissolve in polar solvents. For example, table salt (NaCl), which is ionic, dissolves well in water because they are both polar. However, nonpolar substances, such as oil, do not mix with water because they are not soluble in polar solvents. Moreover, there are scenarios where an 'insoluble' substance can exhibit a degree of solubility due to the hydrotropic action of water, enabling otherwise insoluble substances to dissolve at least slightly in water.

In summary, some substances can dissolve to an extent in certain solvents due to the 'like dissolves like' principle, but insoluble substances by definition do not dissolve readily in any solvents to form true solutions.

Answer:

Option (1), (2) and (5)

Explanation:

Topographic maps are those that illustrate the surface features of different areas. It provides detailed information about an area such as the relief, hills, basins, rivers, and mountains and is constructed in both small and large scale. These maps are often used by geographers and geologists to study about any particular area.

In the given question, these topographic maps are used for recreation purposes including camping, hiking that enables them to lead the path. It is also used by the engineering geologist and engineers for the construction of roads and railways, buildings and houses, as the more resistant and reliable surfaces are traced out and used for these purposes. And mostly used by the geologists in order to understand how these surface features like folds, faults, mountains, and valleys have formed and evolved with the increasing time.

Hence the correct answers are option (1), (2) and (5)

Answer:

1,2 and 5

Explanation:

Answer: The enthalpy change of the reaction is -1322.91 kJ

Explanation:

The chemical equation for the combustion of propane follows:

[tex]C_2H_4(g)+3O_2(g)\rightarrow 2CO_2(g)+2H_2O(g)[/tex]

The equation for the enthalpy change of the above reaction is:

[tex]\Delta H^o_{rxn}=[(2\times \Delta H^o_f_{(CO_2(g))})+(2\times \Delta H^o_f_{(H_2O(g))})]-[(1\times \Delta H^o_f_{(C_2H_4(g))})+(3\times \Delta H^o_f_{(O_2(g))})][/tex]

We are given:

[tex]\Delta H^o_f_{(H_2O(g))}=-241.818kJ/mol\\\Delta H^o_f_{(O_2(g))}=0kJ/mol\\\Delta H^o_f_{(CO_2(g))}=-393.509kJ/mol\\\Delta H^o_f_{(C_2H_4(g))}=52.26kJ/mol[/tex]  

Putting values in above equation, we get:

[tex]\Delta H^o_{rxn}=[(2\times (-393.509))+(2\times (-241.818))]-[(1\times (52.26))+(3\times (0))]\\\\\Delta H^o_{rxn}=-1322.91kJ[/tex]

Hence, the enthalpy change of the reaction is -1322.91 kJ

Answer:

Combination or synthesis

Explanation:

In combination or synthesis, there is formation of a single product from two or more reactants e.g:

               H₂ + I₂ → 2HI

Here a compound forms from the association of the consituent elements.

Other kinds of chemical reactions we have are:

Answer:

c

Explanation:

C4H10 + 13/2 O2 = 4CO2 + 5H2O

0.02 = 328*4.18*45

1= x

making x the subject of the formula you'll get 3084840.0J

Answer:

B) The enthalpy of combustion = 3,084,840 J

Explanation:

Given:

Moles of butane = 0.02

Mass of water, m = 328 g

Initial temperature T1 = 298 K

Final temperature T2 = 343 K

Specific heat of water, c = 4.18 J/g-K

To determine:

Enthalpy of combustion

Explanation:

Heat lost during combustion of butane = heat gained by water

Heat gained (q) by water is given as:

q = mc\Delta T = mc(T2-T1)

substituting for m, c, T2 and [tex]q = 328g*4.18J/g-K*(343-298)K = 61697.8 \ J[/tex]T1

[tex]Enthalpy \ of \ combustion = \frac{q}{moles\ of\ butane} \\\\= \frac{61697.8}{0.02} = 3,084,890\ J[/tex]

Answer:

The formula used to calculate heat of fusion:  

q = m·ΔH f

Explanation:

The formula used to calculate heat of fusion:  

q = m·ΔH f

Answer:

q = m·ΔH f

Explanation:

Answer:

pH = 7.46.

Explanation:

H₂O(l) ⇄ H⁺(aq) + OH⁻(aq),

Kw = [H⁺][OH⁻] = 0.12 x 10⁻¹⁴.  

in pure water and neutral aqueous solution, [H⁺] = [OH⁻]  

So, Kw = [H⁺]²

∴ 0.12 x 10⁻¹⁴ = [H⁺]²

∴ [H⁺] = 3.4 x 10⁻⁸ M.

∵ pH = - log [H⁺]  

pH = - log (3.4 x 10⁻⁸) = 7.46.

Answer:

2) 2 mol of KI in 500. g of water.

Explanation:

The depression in freezing point (ΔTf) can be calculated using the relation:

ΔTf = i.Kf.m,

where, ΔTf is the depression in freezing point.

i is the van 't Hoff factor.

van 't Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass. For most non-electrolytes dissolved in water, the van 't Hoff factor is essentially 1. (i for KCl = 2/1 = 2).

Kf is the molal depression constant of water (Kf = 1.86°C/m).

m is the molality of the solution.

ΔTf ∝ m.

molality (m) of a solution is the no. of moles of dissolved solute in a 1.0 kg of the solvent.

1) 1 mol of KI in 500. g of water :

m of this solution = (no. of moles)/(mass of the solution(kg) = (1.0 mol)/(0.5 kg) = 2 m.

∴ ΔTf = i.Kf.m = (2)(1.86°C/m)(2 m) = 7.44°C.

∴ Freezing point of the solution = 0.0°C - 7.44°C = - 7.44°C.

2) 2 mol of KI in 500. g of water :

m of this solution = (no. of moles)/(mass of the solution(kg) = (2.0 mol)/(0.5 kg) = 4 m.

∴ ΔTf = i.Kf.m = (2)(1.86°C/m)(4 m) = 14.88°C.

∴ Freezing point of the solution = 0.0°C - 14.88°C = - 14.88°C.

3) 1 mol of KI in 1000. g of water :

m of this solution = (no. of moles)/(mass of the solution(kg) = (1.0 mol)/(1.0 kg) = 1 m.

∴ ΔTf = i.Kf.m = (2)(1.86°C/m)(1 m) = 3.72°C.

∴ Freezing point of the solution = 0.0°C - 3.72°C = - 3.72°C.

4) 2 mol of KI in 1000. g of water:

m of this solution = (no. of moles)/(mass of the solution(kg) = (2.0 mol)/(1.0 kg) = 2 m.

∴ ΔTf = i.Kf.m = (2)(1.86°C/m)(2 m) = 7.44°C.

∴ Freezing point of the solution = 0.0°C - 7.44°C = - 7.44°C.

2) 2 mol of KI in 500. g of water.

Option 2, which contains 2 mol of KI in 500 g of water, will freeze at the lowest temperature due to the highest concentration of solute particles, resulting in the largest freezing point depression.

The lowest temperature at which an aqueous solution of KI will freeze is determined by the solution that has the highest concentration of solute particles (ions) in water. Freezing point depression is directly proportional to the molality of the solution, and since KI dissociates into K+ and I- ions in water, each mole of KI will yield two moles of ions.

Comparing the options given:

Therefore, option 2 (2 mol of KI in 500 g of water) would result in the lowest freezing temperature due to having the highest concentration of ions that causes the greatest freezing point depression.

Answer:

I believe the answer isT 2.

Explanation:

he formula for IMA of a first-class lever is effort-distance/resistance-distance.

Answer:

IMA = 2

Explanation:

IMA= din/dout

IMA= 3/1.5

IMA= 2

Answer:

Liquid

Explanation:

Liquid has particles that are held together but can flow past each other and takes the shape of a container, filling it from the bottom up.

Hope this helps!

Answer: Liquid

Explanation:

Solid state : It is a state in which the particles are closely packed and does not have any space between them. They have least kinetic energy due to restricted movement. This state has a definite shape and volume.

Liquid state : It is a state in which the particles are present in random and irregular pattern. The particles are closely arranged but they can move from one place to another and thus have higher kinetic energy as compared to solids. This state has a definite volume but does not have a fixed shape.  It takes the shape of the container.

Gaseous state : It is a state in which the particles are loosely arranged and have a lot of space between them. They have highest kinetic energy. This state has indefinite volume as well as shape.

Thus the phase mentioned is liquid phase.