1. Calculate the average atomic mass of rubidium. Rubidium has two isotopes, 85Rb and 87Rb. 85Rb has an atomic mass of 84.912 amu and occurs at an abundance of 72.17%. 87Rb has an atomic mass of 86.909 amu and occurs at an abundance of 27.83%. Show your work

Answer:

40 ml

Explanation:

boyles law

Pi Vi = PƒVƒ

4 * 20 = 2 * Vƒ

40 ml = Vƒ

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The identity of a metal that has a mass of 27.0g and a volume of 10.0cm is Aluminium. That is option B.

Molar mass is defined as the mass in grams of one mole of an element. This is measured in grams/mole of that substance.

The metal that is 27.0 g and a volume of 10.0 cm3 is aluminium because aluminium is 27 times heavier than 1/12th of the mass of carbon-12 atom.

Therefore, the identity of a metal that has a mass of 27.0g and a volume of 10.0cm is Aluminium.

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Answer:

2.7

Explanation:

The equation of the reaction is

3 BaCl2 + Al2(SO4)3 = 3 BaSO4 + 2 AlCl3

So, frok the coefficients of the equation, the answer is 2.7

2.67 moles of  aluminum chloride can be produce if we have 4.0 moles of aqueous barium chloride, and we mix this with aluminum sulfate solution.

The balanced chemical reaction is :

3BaCl₂ + Al₂(SO₄)₃ ---> 3BaSO₄ + 2AlCl₃

When aqueous barium chloride is mixed with aluminum sulfate solution, a double displacement reaction occurs. The barium ions from barium chloride react with the sulfate ions from aluminum sulfate to form insoluble barium sulfate  precipitate. At the same time, the aluminum ions  from aluminum sulfate react with the chloride ions  from barium chloride to form aluminum chloride.

Given :

Number of Moles of BaCl₂ = 4.0 moles

From the balanced chemical reaction,moles of AlCl₃:

= (4.0 moles BaCl₂) (2 moles AlCl₃/3 moles BaCl₂)

= 2.67 moles AlCl₃

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Answer:

.900 J / g-C°

Explanation:

I assume you are looking for the specific heat of the metal

Specific heat =  J / g-C

                      = 6640 J / 348 g[ (43.6 - 22.4) ] = .900 J / g-C

The specific heat of the unknown metal is approximately [tex]\rm \( 0.90 \, \text{kJ/kg\°C} \)[/tex].

To find the specific heat of the unknown metal, we can use the formula:

[tex]\rm \[ q = m \cdot c \cdot \Delta T \][/tex]

where:

[tex]\rm \( q \)[/tex] = heat absorbed by the metal (in kJ)

[tex]\rm \( m \)[/tex] = mass of the metal (in g)

[tex]\rm \( c \)[/tex] = specific heat of the metal (in kJ/kg·°C)

[tex]\rm \( \Delta T \)[/tex] = change in temperature (in °C)

Given data:

[tex]\( m = 348 \, \text{g} \)\\\( \Delta T = 43.6°C \\\\- 22.4°C = 21.2°C \)\\\( q = 6.64 \, \text{kJ} \)[/tex]

Now, let's rearrange the formula to solve for [tex]\rm \( c \)[/tex]:

[tex]\rm \[ c = \frac{q}{m \cdot \Delta T} \][/tex]

Substitute the values:

[tex]\rm \[ c = \frac{6.64 \, \text{kJ}}{348 \, \text{g} \times 21.2°C} \][/tex]

Convert the mass to kg and temperature to °C:

[tex]\rm \[ c = \frac{6.64 \, \text{kJ}}{0.348 \, \text{kg} \times 21.2\°C} \]\\\\\ c \approx 0.90 \, \text{kJ/kg\°C} \][/tex]

The specific heat of the unknown metal is approximately [tex]\rm \( 0.90 \, \text{kJ/kg\°C} \)[/tex].

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Your question is incomplete, but most probably your full question was,

A piece of unknown metal weighs 348 g. When the metal piece absorbs 6.64 kJ of heat its temperature increases from 22.4°C to 43.6°C. Determine the specific heat of this metal. What is your unknown metal?

Taking into account the definition of calorimetry and latent heat, the heat needed to melt 100.0 grams of ice that is already at 0°C is 33,400 J (option A).

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Latent heat is defined as the energy required by a quantity of substance to change state.

When this change consists of changing from a solid to a liquid phase, it is called heat of fusion and when the change occurs from a liquid to a gaseous state, it is called heat of vaporization.

In this case, the heat Q that is necessary to provide for a mass m of a certain substance to change phase is equal to

Q = m×L

where L is called the latent heat of the substance and depends on the type of phase change.

In this case, you have to melt the ice into liquid water.Being the specific heat of melting of ice is 334 J/g, the heat needed to melt 100 grams of ice is calculated as:

Q= 100 grams× 334 J/g

Solving:

Q= 33,400 J

In summary, the heat needed to melt 100.0 grams of ice that is already at 0°C is 33,400 J (option A).

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Answer:

C.) 42 grams NaOH

Explanation:

To find the mass of NaOH, you need to (1) find the moles (using the molarity equation) and then (2) convert moles to grams (using the molar mass).

(Step 1)

250.0 mL / 1,000 = 0.2500 L

Molarity = moles / volume (L)

4.2 M = moles / 0.2500 L

1.05 = moles

(Step 2)

Molar Mass (NaOH): 22.990 g/mol + 15.998 g/mol + 1.008 g/mol

Molar Mass (NaOH): 39.996 g/mol

1.05 moles NaOH           39.996 g
-----------------------------  x  ------------------  =  42 grams NaOH
                                           1 mole

Answer:

BeCO3 will hydrolyze in an aqueous medium, yielding a basic solution.

Explanation:

In accord with the rules of salt hydrolysis, the cation [tex]Be^{2+}[/tex] can hydrolyze. The anion [tex]CO_{3} ^{2-}[/tex] can also hydrolyze, given that the resulting conjugate acid is weak.

Given that both ions hydrolyze, the Ka (acid ionization constant) and Kb (Base ionization constant) of each reactant (or product [that is, the conjugate acid and base for each ion]) must be compared.

Using the web (hopefully some sort of reference table has been provided to you):

Ka (for Be^2+) = [tex]3 * 10^{-7}[/tex]

Kb (for CO3^2-) = [tex]\frac{Kw (water)}{Ka (HCO3)}[/tex]

= [tex]\frac{1*10^{-14}}{4.7*10^{-11}}[/tex]

= [tex]2.1 * 10^{-4}[/tex]

The Kb > Ka, so the solution will be basic.

Hope this helps! My apologies if this answer is incorrect, I have not done this type of problem in a while.

Answer:

B.) The reaction will shift to the right to produce more product.

Explanation:

When the pressure of a reaction is increased, the equilibrium shifts to the side with less moles of gas.

You can determine the moles of gas by adding the coefficients on each side of the reaction. The reactants have 4 moles of gas (1 + 3 = 4) and the products have 2 moles of gas. Since there are less moles of gas on the product side, the equilibrium will shift to that side. As such, more product will be produced.

The pH of the solution when no base is added is 0.424.

An aqueous solution's acidity or basicity can be determined using the pH scale. The pH values of acidic solutions are typically lower than those of basic or alkaline solutions.

The chemical formula of hypochlorous acid is HClO.

1 mole of HClO produces 1 mole of hydrogen ions and 1 mole of fluoride ions.

KOH (aq) + HClO (aq) → KClO (l) + H2O (l)

To calculate the pH of the solution when no base is added, we use the equation:

[tex]p_{H} = - log {H}^{+}[/tex]

We are given:

[tex]H^{+} = 0.376 M[/tex]

Putting values in the above equation, we get:

[tex]p_{H} = - log (0.376)[/tex]

[tex]p_{H}[/tex] = 0.424

Hence, the pH of the solution when no base is added is 0.424

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Answer:

Explanation:

The term you want is the critical mass. It is the mass needed to trigger a nuclear reaction and keep it going.

Approximately 104 pounds of Uranium 235 is needed for the critical mass to occur. If it is less than 104 pounds, no reaction will occur.

Answer:

B. 400 kPa

Explanation:

the pressure increases, when the temperature increases. and it increases, when the volume decreases.

both cases happen here, each with the factor 2.

so, the pressure increases by the factor 2×2 = 4.

4×100 = 400 kPa

The edge length of the unit cell at the given atomic mass and density of the molybdenum is 314.2 pm.

The cubic unit cell is the smallest repeating unit when all angles are 90 degrees and all lengths are equal.

The volume of the molybdenum is calculated from mass and density of the molybdenum as shown below;

V = (zm/ρN)

where;

V = (2 x 95.96) / (10.28 x 6.02 x 10²³)

V = 3.10 x 10⁻²³ cm³

a³ = V

a = (V)^¹/₃

a = ( 3.10 x 10⁻²³)^¹/₃

a = 3.142 x 10⁻⁸ cm

a = 3.142 x 10⁻¹⁰ m

a = 314.2 x 10⁻¹² m

a = 314.2 pm

Thus, the edge length of the unit cell at the given atomic mass and density of the molybdenum is 314.2 pm.

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Answer:

8 moles = 16 gm of H2 left over

Explanation:

The balanced equation is

2 H2  +  O2   ===> 2 H2 O

20 g H2   =    20 g / 2 gm/mole = 10 moles of H2

32 g O2   =    32g / 32 g / mole = 1 mole O2

From the balanced equation, you can see each 2 moles of H2 requires 1 Mole of O2

  you would need 20 moles of O 2 to react withe the 10 moles of H2

      but you only have 1 mole of O2      so   8 moles of H2 will be left

The number of moles of 210 grams of NaHCO₃ is 2.5 moles.

To calculate the number of moles use the formula

Number of moles = [tex]\frac{\text{Given Mass}}{\text{Molar Mass}}[/tex]

Mass of NaHCO₃ = 210 g

Now we have to find the Molar mass of NaHCO₃

= Atomic mass of Na + Atomic mass of H + Atomic mass of C + 3 (Atomic mass of O)

= 23 + 1 + 12 + 3 (16)

= 36 + 48

= 84 g/mol

Now put the value in above formula we get

Number of moles = [tex]\frac{\text{Given Mass}}{\text{Molar Mass}}[/tex]

                             = [tex]\frac{210\ g}{84\ g/mol}[/tex]

                             = 2.5 moles

Thus from the above conclusion we can say that The number of moles of 210 grams of NaHCO₃ is 2.5 moles.

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Answer:D. In order to restore equilibrium, the reaction shifts right, towards products

Explanation:

Answer:

d

Explanation:

d

Organic transformation sequential equation using catalysts will be as follows:

2CH3-CH2-O => (alc. KOH) => CH2=CH2 + KCl + H2O => (Br2/CCl4) => CH2Br-CH2Br + Zn

CH2Br-CH2Br + Zn => (HBr /Pd) => CH2=CH2+ZnBr2

As can be visualized from above organic transformation equation, conversion of dry ether in presence of alkaline potassium hydroxide results in formation of unstable ethene. This dry unsaturated compound of ethene is stabilized by reaction that happens in presence of bromine or calcium tetrachloride as the catalyst which results in formation of ethylene bromide which in presence of highly efficient palladium as catalyst results in formation of stable ethene as byproduct. Thereby with formation of stable compound of ethylene, it releases zinc bromide as byproduct resulting completion of reaction equation. This stable product ethene is a double bonded carbon structure that is chemically extremely flammable and has planar structure.

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The vapor pressure is obtained as 23.47 torr.

Given that; p = x1p°

p = vapor pressure of the solution

x1 = mole fraction of the solvent

p° = vapor pressure of the pure solvent

Δp = p°(1 - x1)

Δp =x2p°

Δp =  vapor pressure lowering

x2 = mole fraction of the  of the solute

Number of moles of  glycerol =  32.5 g/92 g/mol = 0.35 moles

Number of moles  of water = 500.0 g/18 g/mol = 27.8 moles

Total number of moles = 0.35 moles + 27.8 moles = 28.15 moles

Mole fraction of glycerol = 0.35 moles/28.15 moles = 0.012

Mole fraction of water = 27.8 moles/28.15 moles =0.99

Δp =  0.012 * 23.76 torr

Δp =  0.285 torr

p1 = p° - Δp

p1 = 23.76 torr -  0.285 torr

p1 = 23.47 torr

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Answer:

a.) 1+

Explanation:

Potassium (K) is located in the first column of the periodic table.

These elements have 1 valence electron. As such, in order to obtain a full octet (8 valence electrons), these elements are likely to lose 1 electron. When this occurs, the element gains an overall charge of 1+ because the positively-charged protons now outnumber the negatively-charged electrons by 1.

The IUPAC name of this compound is diamminecarbonylchloroIridium ..

Isomers are structure of compund in different forms but they have same molecular mass .

The cis and trans form are given in the picture

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Answer:

uestion

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Question

I think we make a mistake when we consider that data are qualitative if they come from applying qualitative methods and techniques or if they are collected in qualitative researches. I think we make the same mistake when we consider quantitative all data collected through, for example, questionnaires.

I think we have to consider the qualitative or quantitative character of data looking exclusively at data. Are they numeric? Are they textual or visual?

I think (as Traian Rotariu argues) that quantitative data are numeric and that qualitative data are textual or visual and that we could gather quantitative and qualitative data with each and every method and technique being it qualitative or quantitative.

For example most of the data gathered with questionnaires are qualitative in their primary form: opinions, gender, preferences etc. and just a few are quantitative in their primary form: income, age, children's number And more

Taking into account the definition of dilution, the answer is "The volume of stock solution used is less than 3 Liters."

When it is desired to prepare a less concentrated solution from a more concentrated one, it is called dilution.

Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.

In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.

A dilution is mathematically expressed as:

Ci×Vi = Cf×Vf

where

In this case, you know:

Replacing in the definition of dilution:

10 M× Vi= 1 M× 3 L

Solving:

Vi= (1 M× 3 L)÷ 10 M

Vi= 0.3 L

In summary, to prepare 3 Liters of 1 M solution, you need 0.3 L of the 10 M concentration stock solution and dilute to 3 L. Therefore, the answer is "The volume of stock solution used is less than 3 Liters."

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Answer:

[OH⁻] = 2.2 x 10⁻¹²

Explanation:

(Step 1)

Calculate the pH.

pH = -log[H⁺]

pH = -log[4.6 x 10⁻³]

pH = 2.34

(Step 2)

Find the pOH.

pH + pOH = 14

2.34 + pOH = 14

pOH = 11.66

(Step 3)

Calculate the [OH⁻].

[OH⁻] = 10^(-pOH)

[OH-] = 10^(-11.66)

[OH⁻] = 2.2 x 10⁻¹²

Answer:

A.) [tex]K_b = \frac{[CH_3NH_3^+][OH^-]}{[CH_3NH_2]}[/tex]

Explanation:

The general Kb expression is:

[tex]K_b = \frac{[HA][OH^-]}{[A^-]}[/tex]

In this equation

-----> Kb = equilibrium constant

-----> [HA] = acid

-----> [A⁻] = base

Since liquids are not included in equilibrium expressions, H₂O should not be present. The products are in the numerator while the reactant are in the denominator. In this reaction, CH₃NH₂ is acting as a base and CH₃NH₃⁺ is acting as an acid.

As such, the expression is:

[tex]K_b = \frac{[CH_3NH_3^+][OH^-]}{[CH_3NH_2]}[/tex]

The amount of electricity the plant will use for aluminum production in 1 year is 102×10⁷ KWh of electricity

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

The amount of electricity needed to produce the aluminum for 1 year can be obtained as illustrated below:

From the question given above,

1 Kg of Aluminum required 17 KWh of electricity

Therefore,

60000000 Kg of Aluminum will require = 60000000 × 17 = 102×10⁷ KWh of electricity

Thus, the amount of electricity needed to produce the aluminum for 1 year is 102×10⁷ KWh of electricity

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I hope this helps you ...

Answer:

A.) 1.845

Explanation:

You can find the pOH using the following equation:

pOH = -log[OH⁻]

Since NaOH dissociates into 1 Na⁺ and 1 OH⁻, the concentration of both ions is 0.0143 M.

pOH = -log[OH⁻]

pOH = -log[0.0143]

pOH = 1.845

Answer:

B.) 1.3 atm

Explanation:

To find the new pressure, you need to use Gay-Lussac's Law:

P₁ / T₁ = P₂ / T₂

In this equation, "P₁" and "T₁" represent the initial pressure and temperature. "P₂" and "T₂" represent the final pressure and temperature. After converting the temperatures from Celsius to Kelvin, you can plug the given values into the equation and simplify to find P₂.

P₁ = 1.2 atm                                    P₂ = ? atm

T₁ = 20 °C + 273 = 293 K              T₂ = 35 °C + 273 = 308 K

P₁ / T₁ = P₂ / T₂                                             <----- Gay-Lussac's Law

(1.2 atm) / (293 K) = P₂ / (308 K)                  <----- Insert values

0.0041 = P₂ / (308 K)                                   <----- Simplify left side

1.3 = P₂                                                         <----- Multiply both sides by 308

The equilibrium shift if the HCl concentration is increased to the product.

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

If the concentration of a substance is changed, then the equilibrium will shift in such a way that it minimise the effect of change which occur. If we increase the concentration of a reactant, then the equilibrium will shift to minimize the changes in the direction of the reaction which uses the reactants, so that the reactant concentration decreases.

Thus, we concluded that with increase in the concentration of reactant equilibrium shift forward.

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Answer:

3.) 51.7 L

Explanation:

To find the volume, you need to use the Ideal Gas Law:

PV = nRT

In the equation,

-----> P = pressure (kPa)

-----> V = volume (L)

-----> n = moles

-----> R = Ideal Gas constant (8.314 kPa*L/mol*K)

-----> T = temperature (K)

First, you need to convert the temperature from Celsius to Kelvin. Then, you can plug the given values into the equation and simplify to find "V".

P = 68.0 kPa                          R = 8.314 kPa*L/mol*K

V = ? L                                    T = 27.00 °C + 273 = 300 K

n = 1.41 moles

PV = nRT                                                              <----- Ideal Gas Law

(68.0 kPa)V = (1.41 moles)(8.314 kPa*L/mol*K)(300 K)      <----- Insert values

(68.0 kPa)V = 3516.822                                      <----- Multiply right side

V = 51.7                                                                <----- Divide both sides by 68.0