The isotope sodium-24 has a half-life of 15 hours. Starting with 22 grams, how much remains in 30
hours?

[tex] {\qquad\qquad\huge\underline{{\sf Answer}}} [/tex]

Here we go ~

Energy difference btween the two electronic states can be expressed as :

[tex]{ \qquad \sf  \dashrightarrow \: \Delta E = h\nu} [/tex]

[ h = planks constant,[tex]{\: \nu } [/tex]= frequency ]

[tex] \qquad \sf  \dashrightarrow \:214.68 = 39.79 \times 10 {}^{ - 14} \times \nu[/tex]

[tex]\qquad \sf  \dashrightarrow \: \nu = \cfrac{214.68}{39.79 \times 10 {}^{ - 4} } [/tex]

[tex]\qquad \sf  \dashrightarrow \: \nu = \cfrac{214.68}{39.79 } \times 10 {}^{14} [/tex]

[tex]\qquad \sf  \dashrightarrow \: \nu \approx 5.395 \times10 {}^{14} \:\:hertz[/tex]

Answer:

n2(g)+3h2(g)→2nh3(g) balanced

Explanation:

Wayne Breslyn

Answer:

The correct answer is A

Explanation:

Ionic compounds conduct electricity when molten (liquid) or in an aqueous solution because their ions are free to move from place to place

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A. The heat is needed to melt 100.0 grams of ice that is already at 0°C is +33,400 J.

Specific heat capacity is the quantity of heat needed to raise the temperature per unit mass.

The heat is needed to melt 100.0 grams of ice that is already at 0°C is calculated as follows;

Q = mL

where;

Q = 100 x 334

Q = 33,400 J

Thus, the heat is needed to melt 100.0 grams of ice that is already at 0°C is +33,400 J.

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From the stoichiometry of the reaction, the volume of the steam produced is 82.9 L

The term combustion is the term that is used to describe the kind of reaction that occurs when a substance is being burnt in oxygen. It is an oxidation reaction and the octane is burnt to produce carbon dioxide and steam.

We can try to write down the equation of the reaction as follows;

2C8H18(g) + 25O2(g) ------> 16CO2(g) + 18H2O(g)

Now 1 mole of octane gas occupies 22.4 L

x moles of octane gas occupies 9.1 L

x = 9.1 L  *  1 mole /22.4 L

x = 0.41 moles

Now;

2 mole of octane gas produces 18 moles of steam

0.41 moles of octane gas produces  0.41 moles  * 18 moles/2 mole

= 3.7 moles

1 mole of steam occupies 22.4 L

3.7 moles of steam occupies 3.7 moles *  22.4 L/1 mole

= 82.9 L

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Answer:

131 atm

Explanation:

To find the new pressure, you need to use Boyle's Law:

P₁V₁ = P₂V₂

In this equation, "P₁" and "V₁" represent the initial pressure and volume. "P₂" and "V₂" represent the final pressure and volume. You can find the new pressure (P₂) by plugging the given values into equation and simplifying.

P₁ = 3.88 atm                       P₂ = ? atm

V₁ = 7.74 L                           V₂ = 0.23 L

P₁V₁ = P₂V₂                                                      <----- Boyle's Law

(3.88 atm)(7.74 L) = P₂(0.23 L)                       <----- Insert values

30.0312 = P₂(0.23 L)                                      <----- Simplify left side

131 = P₂                                                          <----- Divide both sides by 0.23

Answer:

2.64 M

Explanation:

To find the molarity, you need to (1) convert grams to moles (via molar mass), then (2) convert mL to L, and then (3) calculate the molarity (via molarity ratio). The final answer should have 3 sig figs to match the sigs figs of the given values.

(Step 1)

Molar Mass (NH₄NO₃): 2(14.007 g/mol) + 4(1.008 g/mol) + 3(15.998 g/mol)

Molar Mass (NH₄NO₃): 80.04 g/mol

66.5 grams NH₄NO₃                1 mole
---------------------------------  x  ----------------------  =  0.831 moles NH₄NO₃
                                             80.04 grams

(Step 2)

1,000 mL = 1 L

 315 mL                1 L
--------------  x  ------------------  =  0.315 L
                        1,000 mL

(Step 3)

Molarity = moles / volume

Molarity = 0.831 moles / 0.315 L

Molarity = 2.64 M

Excess water and impurities. Option A.

In the actual sense of it, no chemical reaction can give over a 100% yield. The upper limit cannot be breached. Thus, if more than a 100% yield is obtained, there is a problem somewhere.

One of the problems could be that the product is not sufficiently dried. In other words, excess water has contributed to the yield of the reaction.

The second likely problem could be that at some points during the reaction, impurities have been introduced. The weight of the impurities will add to the actual yield and give a bogus over a 100% yield.

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Taking into account the Henry's Law, 1.297 g carbon dioxide will dissolve at 790 mm Hg in 1.01 L water.

A change in pressure does not appreciably influence the solubility of solids or liquids or liquids in liquids; however, that of gases in solvents increases when the partial pressure of the gases increases. The solubility of a gas depends on pressure and temperature.

In this way, Henry's Law describes the effect of pressure on the solubility of gases. This law states that the solubility of a gas in contact with the surface of a liquid at a given temperature is directly proportional to the partial pressure of said gas on the liquid.

Mathematically, Henry's law is expressed as:

C=k×P

Where:

At 2 different partial pressure values, the Henry's law is expressed as:

[tex]\frac{C1}{C2} =\frac{P1}{P2}[/tex]

In this case, you know:

Replacing in Henry's Law:

[tex]\frac{1.228\frac{g}{L} }{C2} =\frac{755 mmHg}{790mmHg}[/tex]

Solving:

[tex]1.228\frac{g}{L} =\frac{755 mmHg}{790mmHg}xC2[/tex]

C2= [tex]\frac{1.228\frac{g}{L} }{\frac{755 mmHg}{790mmHg}}[/tex]

C2= 1.285 [tex]\frac{g}{L}[/tex]

Then, the concentration of carbon dioxide at 790 mmHg is 1.285 g/L. But you have 1.01 L of water. So the amount of gas dissolved can be calculated as 1.01 L×1.285 g/L = 1.297 g

Finally, 1.297 g carbon dioxide will dissolve at 790 mm Hg in 1.01 L water.

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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

The best effect of chemicals on the environment is that Chemicals can be helpful or harmful to the environment.

Environmental chemical compounds seek advice from a chemical compound or chemical element present in air, water, meals, soil, dust, or other environmental media which includes customer merchandise.

Chemical substances can be toxic due to the fact they are able to harm us after they enter or touch the frame. exposure to a poisonous substance together with fuel can have an effect on your fitness. due to the fact that drinking gas can motive burns, vomiting, diarrhea and, in very huge amounts, drowsiness or dying, it's far poisonous.

Nutrient loading from over-fertilization can bring about runoff that causes damaging consequences in aquatic ecosystems. sizable publicity to, or misuse of, insecticides can damage non-centered plants and animal, as well as lead to improvement of pesticide-resistant pest species.

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Answer: Lithium - 8

Answer:

Lithium-8

Explanation:

The atom with three protons and five neutrons that has a mass number of eight is known as lithium-8.

The amount of heat transferred from an object depends on the following;

The initial temperature of the object

The specific heat of the object

The mass of the object

Therefore, the answer is all of the above (option B).

What is heat?

Heat is the internal energy of a system in thermodynamic equilibrium due to its temperature.

The amount of heat absorbed or released by an object can be calculated using the following expression:

Q = m × c × ∆T

Where;

Q = quantity of heat

m = mass of object

c = specific heat capacity of object

∆T = change in temperature

Therefore, this suggests that amount of heat transferred from an object depends on the following;

The initial temperature of the object

The specific heat of the object

The mass of the object

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The reaction above is a spontaneous reaction

Cu^2+ + 2Br^- --> Cu + Br2

A spontaneous redox reaction is a special type of redox reaction which involves the release of energy where the electrons are transferred from from an anode to the cathode

General spontaneous redox reactions is found mostly in electrochemical cells

So therefore, the reaction above is a spontaneous reaction.

Cu^2+ + 2Br^- --> Cu + Br2

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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: 1

Explanation: Lithium has a single electron in the second principal energy level, and so we say that lithium has one valence electron.

1 is correct

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The pH of a 0.0100 M sodium benzoate solution is determined as 8.09.

The pH of a solution is a measure of hydrogen (H+) ion concentration, which is, in turn, a measure of acidity of the solution.

pH is can also be determined from pOH of the solution as shown below;

pH = 14 - pOH

let the hydroxyl concentration, OH = x

x²/M = kb

x²/0.01 = 1.5 x 10⁻¹⁰

x² = 1.5 x 10⁻¹²

x = √(1.5 x 10⁻¹²)

x = 1.2247 x 10⁻⁶

pOH = - log(OH⁻)

pOH = -log( 1.2247 x 10⁻⁶)

pOH = 5.91

pH = 14 - 5.91

pH = 8.09

Thus, the pH of a 0.0100 M sodium benzoate solution is determined as 8.09.

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Answer:

NH4

Explanation:

its an acid duhhhhhhhhh

The balanced redox reaction in the chemical reaction is given below:

40H2S + 48H+ + 16MnO4¯ ---> 5S8 + 16Mn2+ + 64H2O

Balancing the redox reaction:

Solution:

1) Half-reactions:

H2S ---> S8

MnO4¯ ---> Mn2+

2) Balance:

8H2S ---> S8 + 16H+ + 16e¯

5e¯ + 8H+ + MnO4¯ ---> Mn2+ + 4H2O

3) Make the number of electrons equal (note that there are no common factors between 5 and 16 except 1):

40H2S ---> 5S8 + 80H+ + 80e¯ <--- factor of 5

80e¯ + 128H+ + 16MnO4¯ ---> 16Mn2+ + 64H2O <---

factor of 16

4) Thus, the final answer is given below;

40H2S + 48H+ + 16MnO4¯ ---> 5S8 + 16Mn2+ + 64H2O

Oxidation-reduction can simply be defined as a special type of chemical reaction in which the oxidation states of the substrate change.

So therefore, the balanced redox reaction in the chemical reaction is given below:

40H2S + 48H+ + 16MnO4¯ ---> 5S8 + 16Mn2+ + 64H2O

Complete question:

Balance the following redox reaction:

MnO4¯ + H2S ---> Mn2+ + S8

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The equilibrium constant of the reaction is 76176.

In chemistry, the equilibrium constant is used to show the extent to which we can convert reactants to products in a given chemical process. A large value of the equilibrium constant shows that most of the reactants are converted into products under the given conditions. A small value of the equilibrium constant shows that most of the reactants are not converted into products.

Thus, if we have the reactions;

(1) 1/2 X2(g) + 1/2 Y2(g) ↔ XY(g)

(2) 2XY(g) ↔ X2(g) + Y2(g)

It then follows that;

K1 = [XY]/[X2]^1/2 [Y2]^1/2

K2 =  [XY]^2/[X2] [Y2]

It is clear that;

K2 = (K1)^2

K2 = (276)^2

K2 = 76176

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Answer:

d

Explanation:

d

Answer:

402 kJ

Explanation:

Because the energy of the reaction is positive, the reaction is endothermic. This means energy is a reactant.

You can determine how much energy/heat is absorbed using the balanced chemical equation. You can convert the moles A using the ratio composed of the coefficient in front of A and the energy required for each reaction.

2A + B + 309 kJ ⇌ 2C + 2D

2.60 moles A             309 kJ
----------------------  x  --------------------  = 402 kJ
                                 2 moles A

Quick boiling of water can be related to the hot weather because in high temperature water changes from liquid state to gaseous state.

Water boils quickly when the weather is hot and warm because hot weather has high temperature which leads to the quick evaporation of the water. In hot weather, the liquid water changes into vapor state very quickly as compared to cold temperature.

So we can conclude that Quick boiling of water can be related to the hot weather because in high temperature water changes from liquid state to gaseous state.

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When the crystals of potassium permanganate are preserved in water, the purple-coloured crystals of potassium permanganate break further into smaller particles that populate the distance between the molecules of water imparting a purple colour to the water. This is an example of diffusion.

Diffusion is the process of movement of solvent from higher concentration to lower concentration through a semipermeable membrane. So, we can form the decision that it cannot occur through a thick membrane from which small molecules cannot pass through.

Osmosis is the direction of solvent particles from a solution that is diluted to a more concentrated one. In contrast, diffusion is the movement of particles from a higher concentration region to a part of lower concentration.

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Answer:

See below

Explanation:

45 kJ / gm   * .77  gm / liter  * 13 liter =  _________  kJ

Burning 13 L of gasoline would produce 450,450 kJ of energy. For calculating the amount of energy produced by burning 13 L of gasoline, we can use the given information that 1 gram of gasoline produces 45.0 kJ of energy when burned and the density of gasoline is 0.77 g/mL.

First, we need to convert the volume of gasoline from liters to milliliters since the density is given in grams per milliliter.

13 L = 13,000 mL

Next, we can calculate the mass of the gasoline using the density:

Mass = Volume x Density

Mass = 13,000 mL x 0.77 g/mL

Mass = 10,010 g

Now, we can calculate the amount of energy produced by multiplying the mass of gasoline by the energy produced per gram:

Energy = Mass x Energy per gram

Energy = 10,010 g x 45.0 kJ/g

Energy = 450,450 kJ

Therefore, burning 13 L of gasoline would produce 450,450 kJ of energy.

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B. At the equivalence point of a titration of the [H+] concentration is equal to 7.

The equivalence point of a titration is a point in titration at which the amount of titrant added is just enough to completely neutralize the analyte solution.

At the equivalence point in an acid-base titration, moles of base equals moles of acid and the solution only contains salt and water.

At the equivalence point, equal amounts of H+ and OH- ions combines as shown below;

H⁺ + OH⁻  → H₂O

The pH of resulting solution is 7.0 (neutral).

Thus, the pH at the equivalence point for this titration will always be 7.0.

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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.