When 50.0 mL of 0.100 M AgNO3 is mixed with 50.0 mL of 0.100 M HCl in a coffee cup calorimeter, the temperature increases from 23.40 °C to 24.21°C. If the specific heat of the solution is 4.184 J/°C·g and its density is 1.00 g/mL, assuming that the calorimeter undergoes no heat change, calculate the enthalpy change for the following reaction in units of kJ/mol AgNO3:AgNO3(aq) + HCl(aq) à AgCl(s) + HNO3(aq)

Answer:

E =  3.6 x 10⁶ J/mol

f =   1.1 x 10 ¹⁶ s⁻¹

λ =  2.6 x 10⁻⁸ m

Explanation:

Rydberg´s equation for hydrogen-like atoms is:

1/λ = Z²Rh (1/n₁² - 1/n₂²)

where  λ = wavelength  

Z² = atomic number of hydrogen-like atom  

 Rh= Rydberg´s constatn                                       

n₁ = principal quantum number of initial state                        

 n₂ = principal quantum number of final state

We also know that E = h(c/ λ ) = hf, where f is frequency equal to c/λ,  so we have all the information needed to answer the questions.

a)  We are asked the energy to remove the electron from 1 mol of B⁴⁺ , that means the transition is from  n₁ = 3 to n₂ = ∞. The term 1/n₂ approaches zero in the infinity so:

Working in  SI units

1/λ =  5² x1.097 x 10⁷ m⁻¹ ( 1/3² - 0) = 3.0 x 10⁷ m⁻¹

E= h(c/ λ )= hc(1/ λ) = 6.626 x 10⁻³⁴ J/s x  3 x 10⁸ m/s x  (3.0 x 10⁷ m⁻¹)

= 6.0x 10⁻¹⁸ J

This is the energy per atom, so per mol of atoms  is

= 6.0x 10⁻¹⁸ J/atom x 6.022 x 10²³ atoms/mol = 3.6 x 10⁶ J/mol

b) f and λ from a transition n= 3 to n=2

1/ λ = 5² x1.097 x 10⁷ m⁻¹ x ( 1/2² - 1/3²) = 3.8 x 10⁷  m⁻¹    ⇒

λ = 1/ 3.8 x 10⁷  m⁻¹ = 2.6 x 10⁻⁸ m

f = 3 x 10⁸ m/s / 2.6 x 10⁻⁸ m = 1.1x 10 ¹⁶ s⁻¹

Answer: The dentist and at least one other dental auxiliary must be present, in the treatment room, during the administration of nitrous oxide. True.

Explanation: there is a minimum standard of care while performing nitrous oxide inhalation by a medical personnel and in addition shall maintain under continuous direct supervision auxiliary personnel who shall be capable of reasonably assisting in procedures, problems and emergencies incident to the used of nitrous oxide inhalation sedation.

samples of matter that contain only one type of element or compound. However, mixtures—samples of matter containing two or more substances physically combined—are more commonly encountered in nature than are pure substances. Similar to a pure substance, the relative composition of a mixture plays an important role in determining its properties. The relative amount of oxygen in a planet’s atmosphere determines its ability to sustain aerobic life. The relative amounts of iron, carbon, nickel, and other elements in steel (a mixture known as an “alloy”) determine its physical strength and resistance to corrosion. The relative amount of the active ingredient in a medicine determines its effectiveness in achieving the desired pharmacological effect. The relative amount of sugar in a beverage determines its sweetness. In this section, we will describe one of the most common ways in which the relative compositions of mixtures may be quantified.

Answer:

Correct statement is A.

Explanation:

Let's see the reactions:

2Na⁺  +  S⁻²  → Na₂S (aq)

This salt is soluble

CuCl₂  (aq)  →  Cu²⁺  +  2Cl⁻

This is an insoluble salt.

Cu²⁺ (aq) +  2Cl⁻ (aq) +  2Na⁺ (aq)  +  S⁻² (aq)  →   2NaCl (aq)  +  CuS (s) ↓

No molecules or gas are formed. (Option D, FALSE)

NaCl does not precipitate, because it'a soluble salt (OPTION E or C are false)

Option B is also false. There is a reaction, of precipitation.

Answer:

A.

Explanation:

Firstly, let’s write a chemical equation for the observation:

Na2S + CuCl2 → CuS + 2NaCl

It should be noted that the copper sulphide is a solid and the sodium chloride is in the aqueous form.

B. Is incorrect. A chemical reaction will occur. The chemical reaction will yield copper sulphide and aqueous sodium chloride.

C. is incorrect. Sodium chloride is in the solution form and cannot precipitate in that form.

D. Is incorrect as no gas is released

E. Is incorrect, only copper sulphide will precipitate.

Answer:

0.91 atm is the partial pressure of just hydrogen gas.

Explanation:

Vapor pressure of water , p= 0.0313 atm

Partial pressure of hydrogen gas = [tex]p_{H_2}[/tex]

Total pressure of the water vapors and hydrogen gas = P = 715 Torr

1 atm = 715 Torr

[tex]715 Torr=\frac{715}{760} atm=0.94 atm[/tex]

According Dalton's law of partial pressure:

[tex]P=p+p_{H_2}[/tex]

[tex]0.94 atm=0.0313 atm+p_{H_2}[/tex]

[tex]p_{H_2}=0.94 atm - 0.0313 atm =0.9087 atm \approx 0.91 atm[/tex]

0.91 atm is the partial pressure of just hydrogen gas.

Answer:

-608KJ/mol

Explanation:

3 C2H2(g) -> C6H6(g)

ΔHrxn = ΔHproduct - ΔHreactant

ΔHrxn= ΔHC6H6 - 3ΔHC2H2

ΔHrxn = 83 - 3(230)

ΔHrxn = -608

Answer:

644.2918 g of turpentine are consumed.

Explanation:

Calculation of the moles of [tex]C[/tex] as:-

Mass = 569 g

Molar mass of carbon = 12.0107 g/mol

The formula for the calculation of moles is shown below:

[tex]moles = \frac{Mass\ taken}{Molar\ mass}[/tex]

Thus,

[tex]Moles= \frac{569\ g}{12.0107\ g/mol}[/tex]

[tex]Moles_{C}= 47.3744\ mol[/tex]

According to the given reaction:-

[tex]C_{10}H_{16}+8Cl_2\rightarrow 10C+16HCl[/tex]

10 moles of C are produced when 1 mole of turpentine undergoes reaction

1 mole of C are produced when [tex]\frac{1}{10}[/tex] mole of turpentine undergoes reaction

47.3744 moles of C are produced when [tex]\frac{1}{10}\times 47.3744[/tex] moles of turpentine undergoes reaction

Moles of turpentine = 4.73744 moles

Molar mass of turpentine = 136 g/mol

[tex]Mass=Moles\times Molar\ mass=4.73744\ moles\times 136\ g/mol=644.2918\ g[/tex]

644.2918 g of turpentine are consumed.

Answer:

At STP, 760mmHg or 1 atm and OK or 273 degrees celcius

Explanation:

The standard temperature and pressure is the temperature and pressure at which we have the molecules of a gas behaving as an ideal gas. At this temperature and pressure, it is expected that the gas exhibits some properties that make it behave like an ideal gas.

This temperature and pressure conform some certain properties on a gas molecule which make us say it is behaving like an ideal gas. Ordinarily at other temperatures and pressures, these properties are not obtainable

Take for instance, one mole of a gas at stp occupies a volume of 22.4L. This particular volume is not obtainable at other temperatures and pressures but at this particular temperature and pressure. One mole of a gas will occupy this said volume no matter its molar mass and constituent elements. This is because at this temperature and pressure, the gas is expected to behave like an ideal gas and thus exhibit the characteristics which are expected of an ideal gas

The given question is incomplete. The complete question is as follows.

At which temperature and pressure will a sample of neon gas behave most like an ideal gas?

Choices are as follow:

(1) 100 K and 0.25 atm

(2) 100 K and 25 atm

(3) 400 K and 0.25 atm

(4) 400 K and 25 atm

Explanation:

At low pressure and high temperature there exists no force of attraction or repulsion between the molecules of a gas. Hence, gases behave ideally at these conditions.

Whereas at low temperature there occurs a decrease in kinetic energy of gas molecules and high pressure causes the molecules to come closer to each other.

As a result, there exists force of attraction between the molecules at low temperature and high pressure and under these conditions gases are known as real gases.

For the given conditions, 400 K and 0.25 atm  depicts low pressure and high temperature.

Thus, we can conclude that at 400 K and 0.25 atm  a sample of neon gas behave most like an ideal gas.

Answer:

Balanced chemical equation:

CuCl₂(aq) + Pb(NO₃)₂(aq) → Cu(NO₃)₂(aq) + PbCl₂(s)

Overall ionic equation:

Cu²⁺(aq) + 2Cl⁻(aq) + Pb²⁺(aq) + 2NO₃⁻(aq) → Cu²⁺(aq) + 2NO₃⁻(aq) + PbCl₂(s)

Net ionic equation:

2Cl⁻(aq) + Pb²⁺(aq) → PbCl₂(s)

Amount of precipitate:

24.72 g

Explanation:

First, let's identify the compounds and the products of the reaction. Copper(II) chloride is CuCl₂, and lead(II) nitrate is Pb(NO₃)₂, after the reaction the products will be PbCl₂ and Cu(NO₃)₂, the first one is an insoluble salt, which will precipitate, and the second one is a soluble salt. So, the balanced chemical equation will be:

CuCl₂(aq) + Pb(NO₃)₂(aq) → Cu(NO₃)₂(aq) + PbCl₂(s)

The ionic equation is done by putting the ions that are presented when the compound ionization at the aqueous solution. The metals have their charged expressed in the name of the compound, and chloride and nitrate have charge -1:

Cu²⁺(aq) + 2Cl⁻(aq) + Pb²⁺(aq) + 2NO₃⁻(aq) → Cu²⁺(aq) + 2NO₃⁻(aq) + PbCl₂(s)

The net ionic equation is the simplified ionic equation. So let's eliminate the ions that are presented on both sides of the equation:

2Cl⁻(aq) + Pb²⁺(aq) → PbCl₂(s)

The stoichiometry of the reaction is 1 mol of CuCl₂ for 1 mol of PbCl₂(the precipitate). The molar mass of the compounds are:

CuCl₂ = 134.452 g/mol

PbCl₂ = 278.106 g/mol

1 mol of CuCl₂ ------------ 1 mol of PbCl₂

Transforming in mass:

134.452 g of CuCl₂ ----------------- 278.106 g of PbCl₂

11.95 g of CuCl₂ ---------------- x

By a simple direct three rule:

134.452x = 3323.3667

x = 24.72 g of PbCl₂

Balanced chemical equation:

CuCl₂(aq) + Pb(NO₃)₂(aq) → Cu(NO₃)₂(aq) + PbCl₂(s)

Overall ionic equation:

Cu²⁺(aq) + 2Cl⁻(aq) + Pb²⁺(aq) + 2NO₃⁻(aq) → Cu²⁺(aq) + 2NO₃⁻(aq) + PbCl₂(s)

Net ionic equation:

2Cl⁻(aq) + Pb²⁺(aq) → PbCl₂(s)

The maximum amount of precipitate that could be formed is 24.72 g.

Copper(II) chloride is CuCl₂, and lead(II) nitrate is Pb(NO₃)₂, these react together with to form PbCl₂ and Cu(NO₃)₂. The balanced chemical equation will be:

CuCl₂(aq) + Pb(NO₃)₂(aq) → Cu(NO₃)₂(aq) + PbCl₂(s)

The metals have their charged expressed in the name of the compound, and chloride and nitrate have charge -1. The ionic equation will be:

Cu²⁺(aq) + 2Cl⁻(aq) + Pb²⁺(aq) + 2NO₃⁻(aq) → Cu²⁺(aq) + 2NO₃⁻(aq) + PbCl₂(s)

Net-ionic equation:

2Cl⁻(aq) + Pb²⁺(aq) → PbCl₂(s)

The stoichiometry of the reaction is 1 mol of CuCl₂ for 1 mol of PbCl₂(the precipitate). The molar mass of the compounds are:

CuCl₂ = 134.452 g/mol

PbCl₂ = 278.106 g/mol

1 mol of CuCl₂ ------------> 1 mol of PbCl₂

Converting to mass:

134.452 g of CuCl₂ ----------------- 278.106 g of PbCl₂

11.95 g of CuCl₂ ---------------- x g

134.452x = 3323.3667

x = 24.72 g of PbCl₂

The maximum amount of precipitate that could be formed is 24.72 g.

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Answer:

B

Explanation:

The species on the right are the more stable acids and bases. A weak acid always has a strong conjugate base as in HCOO- and HCOOH. The acid is a weak acid because it has a strong conjugate base. Similarly, a strong acid has a weak conjugate base as in ClO2- and HClO2. ClO2- is a weak base hence it quickly abstracts a proton to form the acid.

HClO₂ is a stronger acid than HCOOH, and ClO₂⁻ is a weaker base than HCOO⁻. Therefore, the correct answer is B.

To determine the relative strengths of acids and bases in the given reaction:

ClO₂⁻ + HCOOH → HClO₂ + HCOO⁻

We use the Brønsted-Lowry definition of acids and bases. According to the reaction and knowing that equilibrium constants (Keq) of less than one (<1) favor reactants:

Thus, the correct answer is: B. HClO₂ > HCOOH, ClO₂⁻ < HCOO⁻

Answer:

85g

Explanation:

Firstly, from the balanced equation, we can see that one mole of silver nitrate yielded one mole of silver chloride. This is the theoretical relation. We need to get the actual relation. To do this, we will first need to get the number of moles of silver nitrate.

The number of moles is the mass of silver nitrate divided by the molar mass of silver nitrate. The molar mass of silver nitrate is 108 + 14 + 3(16) = 108 + 14 + 48 = 170g/mol

The number of moles is thus 100/170 = 0.59 moles

Since the mole ratio is 1 to 1, the number of moles of silver chloride produced too is 0.59 moles.

To get the mass of silver chloride produced, we simply multiply the number of moles of silver chloride by the molar mass of silver chloride. The molar mass of silver chloride is 108 + 35.5 = 143.5g/mol

The mass is thus = 143.5 * 0.59 = 84.67g

Answer: [tex]2H_2+O_2\longrightarrow 2H_2O[/tex]

Explanation:

Law of conservation of matter : It states that matter can neither be created nor be destroyed but it can only be transformed from one form to another form.

Balanced chemical reaction : It is defined as the reaction in which the number of atoms of individual elements present on reactant side must be equal to the product side.

A) [tex]Ca+Cl_2\longrightarrow CaCl[/tex]

B) [tex]Ca+Cl_2\longrightarrow Ca_2Cl[/tex]

C) [tex]2H_2+O_2\longrightarrow 2H_2O[/tex] is correctly balanced as the number of atoms of hydrogen and oxygen are equal on the both side of the reaction.

D) [tex]H_2+O_2\longrightarrow H_2O[/tex]

Answer:

mixture

Explanation:

Answer: Yes or True

Explanation:

Blood is a Mixture. It's a Homo Mixture because it's made up of more than one substance. a shiny magnesium ribbon is burned in air, to form a grayish powder called magnesium oxide. is this oxide an element, compound or mixture. ... It's a compound, because oxygen and magnesium make magnesium oxide.

Answer:

8 shared electrons

Explanation:

When you are looking for the number of shared electrons via the equation:

S = N-A

Where:

S = means the shared electrons

N = Needed electrons

A = available electrons

"Needed electrons" means how many electrons does it need to have a noble gas configuration, in this case, to complete the octet rule.

"Available electrons" means how many valence electrons is actually available considering the compound or the elements involved in the compound.

To get the needed electrons, treat the elements involved separately.  We have a silicon (Si) atom and 4 chlorine (chlorine) atoms in this compound. Let's list it down first:

              Number of atoms

Si                      1

Cl                     4

Next step is to determine how many electrons should it have in its outer shell to achieve the octet rule. Both of them in this case would be 8. Multiply that by the number of atoms and add up the needed electrons to determine how many you will need for this particular compound.

             Number of atoms             Electrons to achieve Octet       Needed

Si                      1                      x                         8                           =       8

Cl                     4                      x                         8                           =     32

                                                                     TOTAL:                              40

This is now our N. N = 40 electrons

Next step is to determine how many we actually have. Your clue in determining how many valence electrons the atom has is the group. Silicon is in Group 4A, this means it has 4 valence electrons. Chlorine is in Group7A, so ths means it has 7 valence electrons.

So first we write the number of atoms again, then in the next column, you write down the actual number of valence electrons and multiply them. Sum it up to see how many electrons available  in this particular compound.

             Number of atoms             Valence electrons                 Available

Si                      1                      x                         4                           =      4

Cl                     4                      x                         7                          =     28

                                                                     TOTAL:                              32

This is now our A. A = 32 electrons

Now we apply this:

S = N - A

N = 40 electrons

A =  32 electrons

S = 40 - 32 = 8

Number of shared electrons is 8

Beer's law states that the absorbance of a solution is directly proportional to its concentration. Given the molar absorptivity and absorbance for a Cu2+ solution, we can calculate the concentration to be approximately 0.00172 M.

The subject of this question is Beer's Law in the field of chemistry. Beer's Law states that the absorbance of a solution is directly proportional to its concentration, and mathematically it can be expressed as A = εcl. In this formula, A is the absorbance of the solution, ε is the molar absorptivity (the slope in the Beer's law plot), c is the concentration of the solution, and l is the length of the light path through the solution.

In your case, you have been given the slope (ε) from the Beer's law plot, which is 435 L/mol, and the absorbance (A) of the Cu2+ solution, which is 0.75. You need to find the concentration (c), so you can rearrange the formula to c = A / ε.

Substituting the given values into this equation gives: c = 0.75 / 435 = 0.0017241379310344827586206896551724 M

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Answer:

The final pressure in the container at 0°C is 2.49 atm

Explanation:

We apply the Ideal Gases law to know the global pressure.

We need to know, the moles of each:

P He . V He = moles of He . R . 273K

(1atm . 4L) / R . 273K = moles of He  → 0.178 moles

P N₂ . V N₂ = moles of N₂ . R . 273K

(1atm . 6L) / R . 273K = moles of N₂ → 0.268 moles

P Ar . V Ar = moles of Ar . R . 273K

(1atm . 10L) / R . 273K = moles of Ar → 0.446 moles

Total moles: 0.892 moles

P . 8L = 0.892 mol . R . 273K

P = ( 0.892 . R . 273K) / 8L = 2.49 atm

R = 0.082 L.atm/mol.K

The final pressure in the evacuation container at 0 °C is 2.499 atm

To solve this question, we'll begin by calculating the number of mole of each gas. This can be obtained as follow:

Volume (V) = 4 L

Pressure (P) = 1 atm

Gas constant (R) = 0.0821 atm.L/Kmol

Temperature (T) = 0 °C = 273 K

1 × 4 = n × 0.0821 × 273

4 = n × 22.4133

Divide both side by 22.4133

n = 4 / 22.4133

Volume (V) = 6 L

Pressure (P) = 1 atm

Gas constant (R) = 0.0821 atm.L/Kmol

Temperature (T) = 0 °C = 273 K

1 × 6 = n × 0.0821 × 273

6 = n × 22.4133

Divide both side by 22.4133

n = 6 / 22.4133

Volume (V) = 10 L

Pressure (P) = 1 atm

Gas constant (R) = 0.0821 atm.L/Kmol

Temperature (T) = 0 °C = 273 K

PV = nRT

1 × 10 = n × 0.0821 × 273

10 = n × 22.4133

Divide both side by 22.4133

n = 10 / 22.4133

Next, we shall determine the total moles of the gas in the container.

Mole of He = 0.178 mole  

Mole of N₂ = 0.268 mole

Mole of Ar = 0.446 mole

Total mole = 0.178 + 0.268 + 0.446

Finally, we shall determine the pressure in evacuation container. This can be obtained as follow:

Volume (V) = 8 L

Gas constant (R) = 0.0821 atm.L/Kmol

Temperature (T) = 0 °C = 273 K

Number of mole (n) = 0.892 mole

P × 8 = 0.892 × 0.0821 × 273

P × 8 = 19.993

Divide both side by 8

P = 19.993 / 8

Therefore, the final pressure in the evacuation container at 0 °C is 2.499 atm

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Answer:

The correct answer is 1.

Explanation:

The metabolism of homocysteine produces a sulfur amino acid that is normally formed from methionine during the fulfillment of its function as a donor of methyl groups. Metabolic fate such as remethylation and transsulfuration, involving the enzymatic forms of the vitamins folacin, B12, and B6, gives rise to homocysteine and mixed disulfides including so-called protein-linked homocysteine, the main form circulating in plasma. B6 deficiency would have a direct impact on the metabolism of homocysteine to cysteine.

Have a nice day!

Answer:

The answer to your question is -2855 J

Explanation:

Reaction

                     2C₂H₆  +  7O₂   ⇒   4CO₂  +  6H₂O

Formula

Heat of reaction = ΔHrxn = ΣΔHrxn products - ΣΔHrxn reactants

Substitution

ΔHrxn = { 4(-393.5) + 6(-241.8)} - {2(-84.7) + 7(0)}

ΔHrxn = {-1574 -1450.8} - {-169.4}

ΔHrxn = -3024.8 + 169.4

ΔHrxn = -2855.4 J

The standard heat of reaction, or ΔH∘rxn, for the given exothermic reaction is calculated using Hess's Law and the provided standard enthalpies of formation, ΔH∘f. By subtracting the sum of the standard enthalpies of formation of the reactants from that of the products, we find ΔH∘rxn is -2850.0 kJ/mol.

To calculate the standard heat of reaction, or ΔH∘rxn, for the given exothermic reaction, we utilize the principle of Hess's Law, which states that the total enthalpy change for a reaction is the sum of the enthalpy changes for each step of the reaction. So, we can use the standard enthalpies of formation (ΔH∘f) provided for each reactant and product.

Specifically, ΔH∘rxn is calculated by subtracting the sum of the standard enthalpies of formation of the reactants from the sum of the standard enthalpies of formation of the products, each multiplied by their stoichiometric coefficients. For this reaction, this gives:

ΔH∘rxn = [4(-393.5) + 6(-241.8)] - [2(-84.7) + 7(0)] = -2850.0 kJ/mol

So, the standard heat of reaction for this exothermic reaction is -2850.0 kJ/mol.

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The oxidation numbers for the elements Co, Al, C, N, Cl, and Cr in the given compounds are +3, -3, -2, -3, +1, and +6 respectively.

The oxidation numbers for the elements in the compounds are determined as follows:

(a) In LiCoO2, Co has an oxidation number of +3, as lithium contributes +1 and each of the two oxygen atoms contribute -2.
(b) In NaAlH4, Al has an oxidation number of -3, as sodium contributes +1, while hydrogen as a metal hydride contributes -1 each adding up to -4.
(c) In CH3OH, C has an oxidation number of -2, as hydrogen contributes +1 each from the three hydrogen atoms and the fourth hydrogen attached to oxygen contributes -1 and oxygen contributes -2.
(d) In GaN, N has an oxidation number of -3, as gallium contributes +3.
(e) In HClO2, Cl has an oxidation number of +1, as hydrogen contributes +1, and each of the two oxygen atoms contribute -2.
(f) In BaCrO4, Cr has an oxidation number of +6, as barium contributes +2 and each of the four oxygen atoms contribute -2.

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The oxidation numbers for the given elements in their compounds are as follows: Co in LiCoO₂ is +3, Al in NaAlH₄ is +3, C in CH₃OH is -2, N in GaN is -3, Cl in HClO₂ is +3, and Cr in BaCrO₄ is +6.

(a) Co in LiCoO₂: The oxidation number of Co is +3. This is because Lithium (Li) has an oxidation number of +1, and Oxygen (O) has an oxidation number of -2. Since the molecule LiCoO₂ is neutral, the sum of oxidation numbers is zero. Letting 'x' be the oxidation number of Co, we get: 1(+1) + x + 2(-2) = 0, which simplifies to x = +3.

(b) Al in NaAlH₄: The oxidation number of Al is +3. This is because Sodium (Na) has an oxidation number of +1, and Hydrogen (H) has an oxidation number of -1. Since the molecule NaAlH₄ is neutral, the sum of oxidation numbers is zero. Letting 'x' be the oxidation number of Al, we get: 1(+1) + x + 4(-1) = 0, which simplifies to x = +3.

(c) C in CH₃OH (methanol): The oxidation number of C is -2. This is because Hydrogen (H) has an oxidation number of +1, and Oxygen (O) has an oxidation number of -2. Since the molecule CH₃OH is neutral, the sum of oxidation numbers is zero. Letting 'x' be the oxidation number of C, we get: 4(+1) + x + 1(-2) = 0, which simplifies to x = -2.

(d) N in GaN: The oxidation number of N is -3. This is because Gallium (Ga) has an oxidation number of +3. Since the molecule GaN is neutral, the sum of oxidation numbers is zero. Letting 'x' be the oxidation number of N, we get: 1(+3) + x = 0, which simplifies to x = -3.

(e) Cl in HClO₂: The oxidation number of Cl is +3. This is because Hydrogen (H) has an oxidation number of +1, and Oxygen (O) has an oxidation number of -2. Since the molecule HClO₂ is neutral, the sum of oxidation numbers is zero. Letting 'x' be the oxidation number of Cl, we get: 1(+1) + x + 2(-2) = 0, which simplifies to x = +3.

(f) Cr in BaCrO₄: The oxidation number of Cr is +6. This is because Barium (Ba) has an oxidation number of +2, and Oxygen (O) has an oxidation number of -2. Since the molecule BaCrO₄ is neutral, the sum of oxidation numbers is zero. Letting 'x' be the oxidation number of Cr, we get: 1(+2) + x + 4(-2) = 0, which simplifies to x = +6.

Answer:

9.4L

Explanation:

In this particular question, we will need to write a balanced chemical equation for the reaction between sodium and chlorine to form sodium chloride.

Na + Cl ——> NaCl

Hence, we can see that 1 mole of chlorine reacts with 1 mole of sodium.

Now, we need to find the exact number of moles of chlorine atom that reacted with 14.2g of sodium. To do this, we simply divide the mass of the sodium by the atomic mass of the sodium which is 23.

Hence, the mass of sodium reacted is 14.2/23 which equals 0.617 moles

Simply because we have the mole ratio to be 1 to 1, it can be deduced that the number of moles of sodium reacted is also 0.617moles

Now, to get the volume of chlorine, we can use the ideal gas equation.

This is :

PV = nRT

V = nRT/P

Given:

v = ?

n = number of moles = 0.617 moles in this case

T = temperature = 45.3 + 273.15 = 318.45K

P = Pressure = 1.72 atm = 1.72 * 101325 pa = 174,279 Pa

R = molar gas constant = 8314.462L.Pa/K.mol

Inserting all these into the equation will yield:

V = (0.617 * 8314.462 * 318.45)/174,279

V = 9.4L

Answer:

1. 351.62L

2. 15.05 * 10^23 molecules

3. 54.6g

4. 8.29 * 10^21 molecules

Explanation:

1. First we will need to calculate the number of moles present in such number of molecules. We know that one mole contains 6.02 * 10^23 molecules. Hence to calculate the number of moles in 9.45 * 10^24 carbon iv oxide Miley, we simply divide. And that is (9.45 * 10^24) / ( 6.02 * 10^23) = 15.7 moles

At s.t.p, a mole of a gas will occupy a volume of 22.L. Hence 15.7 moles will occupy a volume of 15.7 * 22.4 = 351.62L

2. We first need to calculate the number of moles of calcium metal present in 100g. To do this we simply divide the mass by the atomic mass of calcium. The atomic mass of calcium is 40 amu. The number of moles is thus 100/40 = 2.5 moles

One mole contains 6.02 * 10^23 number of molecules. Hence 2.5 moles will contain 2.5 * 6.02 * 10^23 = 15.05 * 10^23 molecules

3. Firstly we need to calculate the number of moles contained in those number of molecules. What we simply need do is to divide by 6.02 * 10^23

Since the power of 10 is same, we simply divide 5.06 by 6.02 = 0.84 moles

To get the mass, we simply multiply by the atomic mass of zinc. The atomic mass of zinc is 65a.m.u

The mass is thus 0.84 * 65 = 54.6g

4. Firstly we will need to calculate the number of moles here. To do this we divide the mass by the molar mass. The molar mass of lead nitrate is 331g/mol

The number of moles is thus 4.56/331 = 0.014 moles

1 mole contains 6.02 * 10^23 molecules, then 0.014 moles will contain 0.014 * 6.02 * 10^23 molecules = 8.29 * 10^21 molecules

Answer:

40 degrees Celsius

Explanation:

In this kind of question, we need to know what is called a temperature gradient. This means we need to know how the temperature changes with time.

To calculate this , we subtract the initial temperature from the final temperature so that we get the total temperature change. Afterwards, we can now divide the total temperature change by the time taken so we get the gradient.

The total temperature change is 10 degrees celcius. The gradient is 10 degrees Celsius divided by 10 minutes which is equal to 1 degree Celsius per minute. Hence, we conclude that the temperature drops at a rate of 1 degree Celsius per minute.

At the end of next ten minutes, we have a temperature drop of another 10 degrees Celsius. If we subtract this from the final temperature I.e 50, this means we now have a new final temperature of 40 degrees Celsius

The substance with the highest Rf value in thin-layer chromatography using a silica plate would be CH3CH2CH2CH2CH3 (A), because it is the least polar, and thus has lesser degree of interaction with the silica plate, allowing it to travel furthest. Option A

The substance with the highest Rf value in thin-layer chromatography using a silica plate would be the least polar. Rf value depends on the polarity of the substance and the solvent; the less polar the substance, the higher its Rf value. Thin-layer chromatography, or TLC, is a method used in chemistry to separate mixtures.

It works because different compounds in a mixture have different affinities for the stationary phase (silica in this case) and the mobile phase (the solvent).

In this case, we have (A) CH3CH2CH2CH2CH3, (B) HOCH2CH2CH2CH3, (C) HOCH2CH2CH2OH, and (D) HOOCCH2CH2CH3. Molecules B, C, and D all contain a polar -OH group, which would lead to hydrogen bonding with the silica plate, slowing their movement along the plate and decreasing their Rf values.

Molecule A, however, is nonpolar, as it is composed entirely of carbon and hydrogen atoms which have similar electronegativities resulting in minimal polarity. Thus, molecule A will travel furthest and hence have the highest Rf value when using a silica plate in TLC.

Option A

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Answer:

E

Explanation:

As the number of covalent bonds increase, atoms are drawn closer together hence the distance between the atoms decreases. However, the strength of the bonds increases. The bond energy of nitrogen gas (N2) is high because of the strong triple bond between its atoms hence the gas is inert.

As the number of covalent bonds between two atoms increases, the distance between the atoms decreases and the strength of the bond between them increases.

As the number of covalent bonds between two atoms increases, the distance between the atoms decreases and the strength of the bond between them increases. Covalent bonds are formed when atoms share electrons. The stronger the bond, the shorter the distance between the atoms.

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Answer:

E. Evaporation to dryness

Explanation:

E. - Evaporation to dryness is the best method for the recovery of solid KNO3 from an aqueous solution of KNO3.

(KNO3 is very soluble, and will violently decompose if overheated.)

Paper chromatography is for separation of different weight molecules in solution.

B. Filtration  won't work on a solution

C.Titration would contaminate the salt with something else and is used  

to determine concentrations

D. Electrolysis would destroy the salt

Answer:

E

Explanation:

Answer & Explanation:

The law of multiple proportion states that two elements A and B can react with each other to form multiple compounds while one of the two elements remain fixed.

For Example

Hydrogen reacts with oxygen to form:

Water (H2O)

Hydrogen peroxide (H2O2)

The Law of Multiple Proportions states that the mass ratio of elements in different compounds is a simple whole number ratio. In the case of water, the mass ratio of hydrogen to oxygen is always 1:8.

The Law of Multiple Proportions is a principle in chemistry that states that when two elements combine to form different compounds, the ratio of their masses will be a simple whole number ratio. In the case of water, the ratio of hydrogen to oxygen by mass is always 2:16 or 1:8. This means that for every 1 gram of hydrogen in water, there are 8 grams of oxygen. The mass ratio of hydrogen to oxygen in water is therefore constant, not variable.

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Answer:

Ionotophoresis

Explanation:

Ionotophoresis  is the process when "chemical ions are transported through intact skin using electrical current"and is usually used to treat skin infections or in order to create other benefits to the skin.

In order to use this method we need to use a low voltage current direct and we need to ensure a continuous mode with a long pulse duration in order to the ions can flow through the surface of interest.

So then the answer would be:

Ionotophoresis is the process where chemical ions are transported along the intact skin by an electrical current.

Answer:

A

Explanation:

Pico(p) has a value of 10^-12.

Nano(n) has a value of 10^-9.

A. 374ps= 374×10^-12 s

B. 3.74ps= 374×10^-14 s

C. 374ns= 374×10^-9 s

Answer:

Smog

Explanation:

Smog is formed when fossil fuels or turpentine are incompletely burned in the presence of sunlight.

Smog is type of highly dirty air that contain various impurity in it. A form of visible air pollution consists of oxides of ammonia, sulfur , asbestos, haze, and other particulate matter. Man-made smog is derived from emissions from coal burning, vehicle emissions, industrial emissions, forest and agricultural fires, as well as photochemical reactions from these emissions.

Answer:

smog

Explanation:

Answer:

The final temperature of the water is 28.0 °C

Explanation:

Step 1: Data given

Mass of liquid water = 10.0 grams

Temperature = 23.0 °C

Heat absorbed = 209 Joules

Since heat was absorbed by the water, you must have a positive value for  

Δ T

Step 2: Calculate final temperature

q = m*c* ΔT

⇒ with m = the mass of the water = 10.0 grams

⇒ with c = the specific heat of water = 4.184 J/g°C

⇒ with ΔT = The change in temperature = T2 -  T1 = T2 - 23.0 °C

⇒ with q = the heat absorbed = 209 Joule

209 = 10.0 * 4.184 * ΔT

ΔT = 5

ΔT = 5 = T2 - 23

T2 = 28 °C

The final temperature of the water is 28.0 °C

The final temperature of the liquid water sample is 28.0°C.

The specific heat capacity of water is 4.184 J/(g°C). To find the final temperature of the water sample, we can use the equation:

q = mcΔT

Where q is the heat absorbed, m is the mass of the water, c is the specific heat capacity of water, and ΔT is the change in temperature.

Given that m = 10.0 grams, ΔT = final temperature - 23.0°C, and q = 209 joules, we can rearrange the equation to solve for the final temperature:

209 joules = (10.0 grams)(4.184 J/(g°C))(final temperature - 23.0°C)

Simplifying the equation gives:

final temperature - 23.0°C = 209 joules / (10.0 grams)(4.184 J/(g°C))

final temperature - 23.0°C = 4.9886854°C

final temperature = 28.0°C