1400 J of heat energy is added to a sample of iron. The temperature of the sample
rose from 16 C to 20 C. How many moles of iron were used?

6.99 grams of iron (Fe) would produce 10 g of rust (Fe2O3) when iron combines with oxygen to form rust.

The mass of a substance can be calculated as follows:

According to this question, iron combines with oxygen to form rust as follows:

4Fe + 3O2 → 2Fe2O3

First, we convert the mass of rust to moles as follows:

moles of Fe2O3 = 10g/159.69 = 0.063moles

Next, convert moles of Fe to mass as follows:

mass of Fe = 0.125 × 55.85 = 6.99g

Therefore, 6.99 grams of iron (Fe) would produce 10 g of rust (Fe2O3) when iron combines with oxygen to form rust.

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To prepare 0.194 M potassium acetate, add 2.379895 g of potassium acetate to a 125 mL volumetric flask and fill with water to the mark.

Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per litres of a solution.

The following data were obtained from the question:

Molarity of potassium acetate = 0.194 M

Volume of solution = 125 mL

Mass of potassium acetate =?

Next, we shall convert 125 mL to L. This can be obtained as follow:

1000 mL = 1 L

Therefore,

125 mL = 0.125 L

Thus, 125 mL is equivalent to 0.125 L.

Next, we shall determine the number of moles of potassium acetate in the solution. This can be obtained as follow:

Molarity of potassium acetate = 0.194 M

Volume of solution = 0.125 L

Moles of potassium acetate =?

Molarity = [tex]\frac{mole}{Volume}[/tex]

Cross multiply

Mole of potassium acetate = 0.194 M × 0.125

Mole of potassium acetate = 0.02425 mole

Finally, we shall determine the mass of potassium acetate

Molar mass of potassium acetate= 98.14 g/mol

Mass of potassium acetate =?

Mole = [tex]\frac{mass}{Molar mass}[/tex]

Mass of potassium acetate =0.02425  × 98.14

Mass of potassium acetate = 2.379895 g

Thus, to prepare 0.194 M potassium acetate, add 2.379895 g of potassium acetate to a 125 mL volumetric flask and fill with water to the mark.

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Answer:

943.82 ml

Explanation:

Assuming constant pressure

V1/T1 = V2/T2

T2 * V1/T1 = V2       ( T must be in K units)

(220 + 273.15) * 540 / (273.15 + 9) = 943.8 ml

Hydrogen atom is added denotes to something

So the

Hence.

Bromothymol blue will turn yellow

Answer:

Iron - Nails, Utencils, Appliances

Copper - Wiring

Aluminiem - Roofing, Ducting

Answer:

See below

Explanation:

(NH4)2SO4   Molar weight (from periodic table)

       (N =14    H4 = 4   ) * 2 = 36

           S = 32   O4 = 64                  TOTAL = 132 gm/mole

N % =  ( 2*14) / 132 = 21.2%       molar mass = 28 gm

H % = (2 *4) / 132 =  6%            molar mass = 8  gm

S % =  32/132 = 24.2 %             molar mass = 32 gm

O % = (64) / 132 = 48.5%           molar mass = 64  gm

Answer:

10.4 moles

Explanation:

    n / 5.2   =   2  M

     n = 10.4  moles

Take the cuttings from the trees and place them around in different enviornements, if the trees grow up to be the expected size in a different eviornement then the the scientists' claim is correct.

I didn't understand at first either, the question is worded a little strangly, but I believe this should answer the question that was asked.

1066.7 ml of the stock solution must start with, preparing 2.00 L of a 0.800 M NaNO3 solution.

Volume is the space occupied by a three-dimensional object.

By the formula [tex]\rm M_1V_1= M_2V_2[/tex]

M1 is the initial molarity, 1.5 M

M2 is the final molarity, 0.800 M

V1 is the initial volume

V2 is the final volume, 2.00 L

Putting the values in the equation

[tex]\rm 1.5\;M \times V_1= 0.800\;M \times 2.00\;L\\\\V_1 = \dfrac{ 0.800\;M \times 2.00\;L}{1.5\;M} = 1066.7\;ml[/tex]

Thus, the initial volume is 1066.7 ml

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Buffers are the solution that resists the change in pH. 1.39 ml of 5.90 M sodium hydroxide must be added to raise the pH to 5.75.

Henderson–Hasselbalch equation is used to determine the pH of the buffer by the equilibrium concentration of the acid and the conjugate base.

Moles of acetic acid are calculated as:

[tex]0.480 \times 0.0215 = 0.01032[/tex]

Moles of sodium acetate are calculated as:

[tex]0.480 \times 0.0275 = 0.0132[/tex]

The total number of moles is = 0.02352

Now, using the Henderson–Hasselbalch equation:

[tex]\rm pH = \rm pKa + log \dfrac{[Acetate]}{[Acetic\; acid]}[/tex]

Given,

pH = 5.75

pKa = 4.74

Substituting values in the above equation:

[tex]\begin{aligned} 5.75 &= 4.74 +\rm log \rm \dfrac{[Acetate]}{[Acetic\; acid]}\\\\10.2329 &= \rm \dfrac{[Acetate]}{[Acetic\; acid]}\end{aligned}[/tex]

Solving further:

[tex]\begin{aligned} 10.2329 &= 0.02352 - \rm \dfrac{[Acetic\; acid]}{[Acetic\; acid]}\\\\11.2329\; \rm [Acetic \; acid] &= 0.02352 \\\\&= 0.002093\end{aligned}[/tex]

Moles of acetate is calculated as:

0.02352 moles - 0.002093 moles = 0.021427 moles

Initial moles of acetate were 0.0132, added moles of acetate by the addition of the sodium hydroxide resulted in, 0.021427  - 0.0132 = 0.00822 moles of sodium hydroxide.

Volume is calculated as:

[tex]0.00822 \;\rm moles \times \dfrac{1\;\rm L}{5.90\;\rm M} = 0.00139 L[/tex]

Therefore, 1.39 mL of 5.90M of sodium hydroxide is added.

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Answer:

a. energy changes during heating.

b. energy changes during chemical reactions.

c. color changes during chemical reactions.

d. Both (a) and (b)

Explanation:

The answer is D.Both (a) and (b)

Answer:

The 4th statement. Because sulfur is not malleable.

Answer:

d

Explanation:

Answer:

it's 8

Explanation:

the last group of the periodic table is group 8. so all elements in a group should have the same number of valency electrons

Balanced chemical equation for the reaction between sulfuric acid & solid aluminum hydroxide to form liquid water and a soluble salt is 3H₂SO₄ + 2Al(OH)₃  Al₂(SO₄)₃ + 6H₂O.

Balanced chemical equations are those in which all entities are present in same amount on both sides of the chemical equation.

Balanced chemical reaction for the given compounds will be shown as:

3H₂SO₄ + 2Al(OH)₃  Al₂(SO₄)₃ + 6H₂O

Above chemical equation is the balanced equation as all atoms are present in same amount on the left side as well as on the right side of the reaction.

Hence balanced equation is 3H₂SO₄ + 2Al(OH)₃  Al₂(SO₄)₃ + 6H₂O.

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Answer:

The balloon will expand

Explanation:

Steam needs more space than the equivalent wt amount of liquid

696.32 mmHg is the final pressure of the gas.

The ideal gas equation, pV = nRT, is an equation used to calculate either the pressure, volume, temperature or number of moles of a gas.

Given data:

[tex]P_1[/tex] = 720 mmHg              

[tex]P_2[/tex] = ?

[tex]n_1[/tex] = 2.5 mol                

[tex]n_2[/tex] = 3.2 mol

[tex]V_1[/tex] = 34 L            

[tex]V_2[/tex] = 45 L

Formula

Combined gas law

[tex]\frac{P_1 V_1}{n_1} = \frac{P_2 V_2}{n_2}[/tex]

[tex]P_2[/tex] = 696.32 mmHg

Hence, 696.32 mmHg is the final pressure of the gas.

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Answer:

battery. you use it for your remotes. vinegar. you use vinegar for cooking of cleaning. nail polish remover. you use this for removing nail polish

Answer:

40

Explanation:

because NaOH makes 40 grams.

Entropy Change is the measure of the randomness of the thermodynamic system. The entropy change for the reaction is -49.3 J/K.

Entropy change is the ratio of the heat transfer of the system to the absolute temperature of the system.

The entropy of nickel = 182.1 J/mol. K

The entropy of oxygen = 205.0 J/mol. K

The entropy of nickel oxide = 37.99 J/mol. K

Entropy change is calculated as:

[tex]\begin{aligned}\Delta \rm S &= 2(37.99)-2(182.1)-205\\\\&= 75.98 - 364.2 - 205\\\\&= -493.22 \end{aligned}[/tex]

Therefore, -49.3 J/K is the entropy change.

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Answer:The equilibrium constant (kc) for the reaction 2HCl(g) =H2(g)+Cl2 (g) is 4×10^-34 at 25°C.

Explanation:

In a nuclear fission reaction, a freely moving neutron is introduced to a nuclear fuel, then a neutron is absorbed by an atom's nucleus.

Nuclear fission is a process in which an unstable nuclei will convert into stable nuclei after releasing the energy in the form of particles.

When we introduce a freely moving neutron to the nuclear fuel of uranium-235 nuclei then this introduced neutron was absorbed by the nuclei and makes the nuclei more unstable. Then this unstable nuclei will convert into two nuclei in the addition of three neutrons.

Hence, a neutron is absorbed by an atom's nucleus.

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Answer:

liquid

Explanation:

A solid is defined as substance with a set volume and form. A liquid is defined as substance with a set volume but no fixed form. A gas is substance that does not have a definite volume or shape. Plasma, like a gas, has no set volume or shape.

1.648 moles of ammonia will be required to produce 0.824 moles of nitrogen gas.

Mole is a very important unit of measurement that chemists use. A mole of something means you have 602,214,076,000,000,000,000,000 of that thing, like how having a dozen eggs means you have twelve eggs.

According to the reaction, 1 mole of nitrogen gas is produced by 2 moles of ammonia.

Then, 0.824 moles of nitrogen gas will be produced by:

1.648 moles of ammonia will be required to produce 0.824 moles of nitrogen gas.

Hence, 1.648 moles of ammonia will be required to produce 0.824 moles of nitrogen gas.

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Answer:Seeds are great sources of fiber. They also contain healthy monounsaturated fats, polyunsaturated fats and many important vitamins, minerals and antioxidants. When consumed as part of a healthy diet, seeds can help reduce blood sugar, cholesterol and blood pressure

Explanation:

Answer:

Seeds grow plants wherever they fall is in the right condition and can be used as a sort of food for humans

Explanation:

What Renata has granted to the manufacturer of the colored hair dye is called a patent.

A patent is a right given to a manufacturer to be the sole producer of a product for a given period of time. Usually, the patent has to last for a given number of years after which the technology becomes commonplace.

Hence, what Renata has granted to the manufacturer of the colored hair dye is called a patent.

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Answer:

c. contraction

Explanation:

Heating will cause substances to expand, or change their state (like solid to liquid) or it may be a chemical reaction.

Intermolecular forces are the forces present between the molecules. The London dispersion forces are the strongest interparticle forces present in the ethane.

London dispersion forces are the intermolecular forces are the temporary forces present between the induced dipole formed by the electrons occupied in the atom.

The electrons of the atom are distributed symmetrically and are dispersed just as the light in quanta. In ethane molecule ionic, and hydrogen forces are absent and only LDF and dipole-dipole are present.

Therefore, LDF and dipole-dipole are the intermolecular forces that are present in ethane.

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The electronegativity of the element affects the ability of its compounds to dissolve in different solvents.

Electronegativity is a measure of an atom's ability to attract shared electrons to itself.

Polar bonds have a positive and negative side to them, and therefore can attract water dipoles and dissolve in water.

If the polarities of the solvent and solute match (both are polar or both are nonpolar), then the solute will probably dissolve.

If the polarities of the solvent and solute are different (one is polar, one is nonpolar), the solute probably won't dissolve.

Hence, option D is correct.

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