Why is it necessary to cool a hot , supersaturated solution slowly during a recrystallization?

Answer:B apez

Explanation:

Answer:

The type of bond is determined by the difference in elecronegtivity of the atom

Explanation:

A P E X

Answer:

Q = 66984.43 J

Explanation:

Given data:

Mass of water = 1.8 Kg (1.8Kg×1000 g/1 Kg =1800 g)

Initial temperature = 8.4°C

Final temperature = 17.3°C

Specific heat capacity of water = 4.1813 J/g.°C

Heat required = ?

Solution:

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 17.3°C - 8.4°C

ΔT = 8.9°C

Q = 1800 g ×  4.1813 J/g.°C ×8.9°C

Q = 66984.43 J

Answer:

4Al + 3O₂ →   2Al₂O₃

Explanation:

    4Al + 3O₂ →   2Al₂O₃

Only this reaction above obeys the law of conservation of mass. The others flout the rule.

The law of conservation of mass states that "matter is neither created nor destroyed in a chemical reaction but are simply transformed from one form to another".

By this law, the number of atoms on both sides of expression must be the same;

                                                    Number of atoms

Elements              Left hand side                                 Right hand side

  Al                                    4                                                     4

  O                                    6                                                    6

Answer:

B

Explanation:

a chemical change is making a new substance and physical change with a result in a different state of matter:)

Answer:

[tex]atoms\ Fe=6.03x10^{24}atoms[/tex]

Explanation:

Hello!

In this case, since the mass of iron (III) oxide is missing we use 80.0 g as found on similar problems. In such a way, since iron (III) molar mass is 159.70 g/mol, one mole of iron (III) oxide has two moles of iron (subscript) and one mole of atoms of iron have 6.022x10²³ atoms (Avogadro's number), the correct number of atoms in such sample is:

[tex]atoms \ Fe=80.0gFe_2O_3*\frac{1molFe_2O_3}{159.70gFe_2O_3}*\frac{2molFe}{1molFe_2O_3}*\frac{6.022x10^{23}atoms}{1molFe} \\\\atoms\ Fe=6.03x10^{24}atoms[/tex]

Which is shown with three significant figures as 80.0 g has three as well.

Best regards!

Answer:

= 15.51 mL

Explanation:

Here's is the reaction:

2HgO(s) ⇒ 2 Hg(s)+O₂(g)

In this reaction 2mol HgO =  1mol O₂

The molecular weight of HgO = 216.59g

so, 3.0g HgO = 3.0g x 1.00molHgO/216.59gHgO

= 0.0138511 molHgO

The amount of Oxygen follows:

0.0138511 molHgOx1/2= 0.00692555 mol O₂

Now, volume of 1 any gas = 22400mL

so, 0.00692555 mol O₂ x22400mLO₂/1mol O₂

= 15.513232mL O₂

Answer:

Ionic bonds form when a nonmetal and a metal exchange electrons, while covalent bonds form when electrons are shared between two nonmetals. ... Atoms form covalent bonds in order to reach a more stable state. A given nonmetal atom can form a single, double, or triple bond with another nonmetal.

Ionic bonds form when a nonmetal and a metal exchange electrons, while covalent bonds form when electrons are shared between two nonmetals. ... Atoms form covalent bonds in order to reach a more stable state. A given nonmetal atom can form a single, double, or triple bond with another nonmetal.

Answer:

A formula car is a single seat, open cockpit, open wheel racing car with substantial front and rear wings and an engine positioned behind the driver intended to be used in competition.

Answer:

Crystalline solids have well-defined edges and faces, diffract x-rays, and tend to have sharp melting points. In contrast, amorphous solids have irregular or curved surfaces, do not give well-resolved x-ray diffraction patterns, and melt over a wide range of temperatures.

Explanation:

Hope this helped!

Answer:

Crystalline solids have well-defined edges and faces, diffract x-rays, and tend to have sharp melting points. In contrast, amorphous solids have irregular or curved surfaces, do not give well-resolved x-ray diffraction patterns, and melt over a wide range of temperatures.

Explanation:

dicing potatoes, because the molecules are separated but remain the same substance

Answer:

For the people wondering, yes, dicing potatoes is the correct answer. Because a new substance has not formed.

Answer:

17.09g/L

Explanation:

Density = total mass of elements/ volume

We need to find the mass of each mixture constituents using their molar mass:

mole = mass/molar mass

For Neon (Ne) which contains 0.650mol;

0.650 = mass/20.18

mass = 0.650 × 20.18

mass = 13.12g

For Krypton (Kr) which contains 0.321mol;

0.321 = mass/83.79

mass = 0.321 × 83.79

mass = 26.89g

For Xenon (Xe) which contains 0.190mol;

0.190 = mass/131.3

mass = 0.190 × 131.3

mass = 24.95g

Total mass = 13.12g + 26.89g + 24.95g = 64.96g

Density = total mass / volume

Density = 64.96g / 3.80L

Density of the mixture = 17.09g/L

Answer:

Fraction of association = 0.01

pH = 11

Explanation:

A weak base, B, is in equilibrium with water as follows:

B(aq) + H2O(l) ⇄ BH⁺(aq) + OH⁻(aq)

Where Kb is defined as:

Kb = 1.00x10⁻⁵ = [BH⁺] [OH⁻] / [B]

Some B will react producing BH⁺ and OH⁻:

[BH⁺] = X

[OH⁻] = X

[B] = 0.100M - X

As Kb <<< [B] we can say:

[B] ≈ 0.100M

Replacing:

1.00x10⁻⁵ = [X] [X] / [0.100]

1.00x10⁻⁶ = X²

X = 1x10⁻³M = [BH⁺] = [OH⁻]

The fraction of association is [BH⁺] / [B] = 1x10⁻³M / 0.100M = 0.01

As [OH⁻] = 1x10⁻³M, pOH = -log[OH⁻] = 3

pH = 14- pOH

Answer:

[tex]E=4.3\times 10^{-19}\ J[/tex]

Explanation:

Given that,

The wavelength of a photon of blue light is 462 nm

We need to find the energy of this photon. The formula for the energy of a photon is given by :

[tex]E=\dfrac{hc}{\lambda}\\\\E=\dfrac{6.63\times 10^{-34}\times 3\times 10^8}{462\times 10^{-9}}\\\\=4.3\times 10^{-19}\ J[/tex]

So, the energy of this photon is [tex]4.3\times 10^{-19}\ J[/tex].

Answer:

C. Alkaline Metal ok thanks

Answer:

is it ok na I hope this answers are ok

Answer:

Answer is: C) high melting point and high boiling point.

Explanation:

HOPE IT HELPS

Your Welcome

Mark me Brianly!!!

Answer:

C

Explanation:

polar has unequal sharing of electrons that has the lone pairs which has the electronegativity difference. can be mixed with water.

Answer:

Molecular: [tex]Sr(NO_3)_2(aq) +Li_2SO_4(aq)\rightarrow SrSO_4(s)+2LiNO_3(aq)[/tex]

Ionic: [tex]Sr^{2+}(aq)+2NO_3^-(aq) +2Li^{2+}(aq)+SO_4(aq)^{2-}\rightarrow SrSO_4(s)+2Li^+(aq)+2NO_3^-(aq)[/tex]Net ionic: [tex]Sr^{2}(aq)+SO_4(aq)^{2-}\rightarrow SrSO_4(s)[/tex]

Explanation:

Hello!

In this case, since the molecular, ionic and net ionic equations show the complete molecules, ions and resulting ions respectively, for the reaction between strontium nitrate and lithium sulfate, we can notice the formation of solid strontium sulfate and lithium nitrate as shown below:

[tex]Sr(NO_3)_2(aq) +Li_2SO_4(aq)\rightarrow SrSO_4(s)+2LiNO_3(aq)[/tex]

Which is the molecular equation showing both reactants and products as molecules. Then, the ionic equation shows all the reactants and products as ions, considering that aqueous solutions dissociate whereas solid, liquid and gaseous molecules do not, therefore, we obtain:

[tex]Sr^{2+}(aq)+2NO_3^-(aq) +2Li^{2+}(aq)+SO_4(aq)^{2-}\rightarrow SrSO_4(s)+2Li^+(aq)+2NO_3^-(aq)[/tex]

Finally, for the net ionic equation, we cancel out the spectator ions, which are those at both reactants and products:

[tex]Sr^{2+}(aq)+SO_4(aq)^{2-}\rightarrow SrSO_4(s)[/tex]

Best regards!

A further explanation is below.

Given:

Strontium nitrate reacts with Lithium sulfate just to produce Strontium sulfate ([tex]Sr(NO_3)_2[/tex]) and Lithium nitrate ([tex]Li NO_3[/tex]).

The molecular equation will be:

→ [tex]Sr(NO_3)_2(aq) +Li_2SO_4(aq) \rightarrow SrSO_4 (s) +2LiNO_3 (aq)[/tex]

The complete ionic equation will be:

→ [tex]Sr^{2+} (aq) +2NO_3^- (aq) +2Li^+ (aq)+ SO_4^{2-} (aq) \rightarrow SrSO_4 (s)+2Li^+ (aq) +2NO_3^- (aq)[/tex]

By removing the uncharged ions from equation's will be:

Spectator ion:

→ [tex]2Li^+ (aq), 2NO_3^- (aq)[/tex]

Net ionic equation will be:

→ [tex]Sr^{2+}(aq)+SO_4^{2-} (aq) \rightarrow SrSO_4 (s)[/tex]

Thus the response above is right.

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Answer:

I guess covalent bond is formed

Answer:

mineral crystal growth

acid rain

carbonic acid

Answer:

Mineral crystal growth, Acid rain, Carbonic acid

Answer:

2.5%

Explanation:

Given

M1 = 7.50%

M2 = ?

V1 = 25.0mL

V2 = 75.00mL

M1V1=M2V2

7.5x25=M2x75

M2=2.5%

The NaCl of a solution made by diluting 25.0 ml of a 7.50 (m/v)% NaCl solution to a total volume of 75.00 ml is 2.5 (m/v)%.

Solution is defined as a continuous variation of two or more substances in their relative proportions up to what is known as the limit of solubility.  A solute is the name for the substance that dissolves to create a solution. A solvent is the material that a solute will dissolve in. Sugar is the solute and water is the solvent in a sugar-water solution.

To calculate the molarity of NaCl

We use M1V1 = M2V2

Given M1 = 7.50 (m/v)%

V1 = 25.0 ml

V2 = 75.0 ml

M2 = M1 V1 / V2

M2 = 7.50 x 25.0 / 75.0

M2 = 2.5 (m/v)%

Thus, the NaCl of a solution made by diluting 25.0 ml of a 7.50 (m/v)% NaCl solution to a total volume of 75.00 ml is 2.5 (m/v)%.

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Answer:

[tex]m_{K_2O}^{by\ K} =3.01gK_2O[/tex]

Explanation:

Hello!

In this case, since 2.50 g of both potassium (molar mass = 39.1 g/mol) and gaseous oxygen (molar mass = 32.0 g/mol) react in a 4:1 and 1:2 mole ratio respectively, to produce potassium oxide (molar mass = 94.2 g/mol), we evaluate the mass of potassium oxide yielded by each reactant in order to identify the limiting one via stoichiometry:

[tex]m_{K_2O}^{by\ K}=2.50gK*\frac{1molK}{39.1gK}*\frac{2molK_2O}{4molK}*\frac{94.2gK_2O}{1molK_2O} =3.01gK_2O\\\\m_{K_2O}^{by\ O_2}=2.50gO_2*\frac{1molO_2}{32.0gO_2}*\frac{2molK_2O}{1molO_2}*\frac{94.2gK_2O}{1molK_2O} =14.7gK_2O[/tex]

Thus, since the 2.50 g of potassium yields 3.01 g of potassium oxide, we infer it is the limiting reactant and that is the mass of produced product by the reaction.

Best regards!

Answer: Calculating mass quick check

1. The mass of the reactants must be equal to the mass of the products. The total number of moles of the reactants can be more or less than the total number of moles of the products.

2. Divide the mass of the reactant by its molar mass to find the number of moles of the reactant. Use the chemical equation to find the number of moles of the product. Multiply the number of moles of the product by its molar mass to find the mass of the product.

3. 2(108 g/mol)+32 g/mol=248 g/mol; (248 g/mol)(0.02 mol)=4.96 g

4. 19.5 g

5. 853.5 g

You're welcome

Answer:

Like Roman said Avogadro's number is the key to your problem. The value that you'll use on paper is 6.022x10^23. Luckily in our case a mol specifically refers to the amount of atoms. Its a weird concept but 1.97 mol of Aluminum is the exact same amount of atoms as say helium. The only differences lay in the total mass of the sample.

The correct answer is Hot water increases the collision rate of molecules, causing the reaction to occur faster.

Explanation:

Temperature is directly related to the kinetic energy or movement of molecules in a substance. In this context, a higher temperature leads to more kinetic energy or more collision between molecules. At the same time, a chemical reaction involves molecules of two or more substances colliding and creating bonds to form new substances. This implies an increase in temperature means molecules colliding faster, new substances forming in a shorter time, and therefore a faster chemical reaction. According to this, the first answer is correct.

The volume of NaOH that would be needed to reach the equivalence point is :  19 mL

Given data

volume of HCL = 50 mL = 0.05 L

conc of HCL = 0.100 M

volume of NaOH = ?

conc of NaOH = 0.100 M

New conc of added base = 0.270 M

At equivalence ;

moles of OH⁻ ions = moles of H⁺ ions

              0.05 * 0.1 = 0.27 * v

therefore the volume ( v ) = ( 0.05 * 0.1 ) / 0.27

                                          = 0.019 L = 19 mL

Hence we can conclude that The volume of NaOH that would be needed to reach the equivalence point is :  19 mL .

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