A reaction occurs in a calorimeter, resulting in the starting temperature of 38.8 ℃ and final temperature 21.0 ℃. What can you say about the reaction and the enthalpy change (ΔH) during the reaction?

Answer:

New molarity = M₂ = 0.167 M

Explanation:

Given data:

New molarity = M₂ = ?

Final volume = V₂ = 100mL + 20 mL = 120 mL

Initial volume =M₁ =  100 mL

Initial molarity =V₁ = 0.2 M

Solution:

M₁V₁       =    M₂V₂

0.2 M × 100 mL = M₂ × 100 mL

M₂ = 0.2 M × 100 mL/120 mL

M₂ = 20 M.mL/120 mL

M₂ = 0.167 M

Answer:

Examples of decomposition reactions include the breakdown of hydrogen peroxide to water and oxygen, and the breakdown of water to hydrogen and oxygen.

Answer:

1.58×10² nm

Explanation:

Given data:

Frequency of light = 1.90 ×10¹⁵ Hz

wavelength of light = ?

Solution:

Speed of light = wavelength  × Frequency

Speed of light = 3×10⁸ m/s

3×10⁸ m/s  = λ × 1.90 ×10¹⁵ Hz

 Hz = s⁻¹

λ =  3×10⁸ m/s / 1.90 ×10¹⁵s⁻¹

λ = 1.58×10⁻⁷ m

meter to nm:

1.58×10⁻⁷ m ×10⁹ nm/ 1m

1.58×10² nm

Answer:

3.15 V

Explanation:

Step 1: Write the balanced cell reaction

Co(s) + F₂(g) ⟶ Co²⁺(aq) + 2 F⁻(aq)

Step 2: Identify both half-reactions:

Cathode (reduction): F₂(g) + 2 e⁻ ⟶ 2 F⁻(aq)    E°red = 2.87 V

Anode (oxidation): Co(s) ⟶ Co²⁺(aq) + 2 e⁻      E°red = -0.28 V

Step 2: Calculate the standard cell potential

We will use the following expression.

E°cell = E°red,cathode - E°red,anode

E°cell = 2.87 V - (-0.28 V) = 3.15 V

Given E°cell > 0, the reaction is spontaneous.

Taking into account the definition of standard cell potential, E°cell has a value of 3.15 V.

The balanced cell reaction is:

Co(s) + F₂(g) ⟶ Co²⁺(aq) + 2 F⁻(aq)

First of all, it must be taken into account that oxidation is a reaction where an atom, ion or molecule loses electrons while reduction corresponds to the gain of electrons from an atom, ion or molecule.

Both oxidation and reduction depend on the change in the oxidation state of the atom, that is, on the difference in the charge of the atom in a reaction.

The oxidation and reduction reactions always occur simultaneously for what are generally known as oxidation-reduction reactions or redox reactions.

So, the anode corresponds to the negative electrode which normally oxidizes in the electrolytic chemical reaction while the cathode corresponds to the positive electrode which normally reduces its oxidation state when it receives electrons.

Si, in this case, the both half-reactions will be:

The potential of an Ecel cell is a measure of the difference in electronic energy between the two electrodes. The electronic energy of each electrode is related to the force with which the reaction occurs at the electrode-solution interface. The unit in which it is measured is the volt.

In electrochemistry, because a cell reaction is made up of two half-cell reactions, each of which has a characteristic electrode potential, the potentials measure the driving force of the two half-reactions.

The cell potential is obtained by subtracting the potentials of both half cells as shown below:

E°cell= Ecatode - Eanode

So, in this case, the Ecell is calculated as:

E°cell = 2.87 V - (-0.28 V) = 3.15 V

In summary, E°cell has a value of 3.15 V.

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Answer:

Mass of Mg  = 120 g

1.23 moles of Cu

Explanation:

A)

Given data:

Number of moles of Mg = 5 mol

Mass of Mg = ?

Solution:

Number of moles = mass/molar mass

Molar mass of magnesium is 24 g/mol.

5 mol = mass/ 24 g/mol

Mass = 5 mol × 24 g/mol

Mass = 120 g

B) Given data:

Number of atoms of Cu = 7.4 ×10²³ atom

Number of moles of Cu = ?

Solution:

Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.  The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ atoms

7.4 ×10²³ atom × 1 mol / 6.022 × 10²³ atom

1.23 moles of Cu

Answer:

Basically, in the case of sodium and potassium the increase in shell size outweighs the pull of the core on the outer shell electron and so potassium is less dense than sodium. When we more from Na to K, effect of increase in volume is more pronounced as compared to effect of increase in atomic mass.

Answer: C. Heat transfers thermal energy from the student's hand to the ice.

Explanation:  It seems confusing; b and c seem to be saying the same thing, but the definition of heat is the transfer of thermal energy from a warmer object to a colder object.

Answer:

0.06642 moles of mercury

Explanation:

Step 1: Given data

Moles of mercury: 4.000 × 10²² atoms

Step 2: Calculate the number of moles of mercury that correspond to 4.000 × 10²² atoms of mercury

To convert atoms to moles, we need to consider the Avogadro's number: there are 6.022 × 10²³ atoms of mercury per mole of mercury.

4.000 × 10²² atoms × (1 mol/6.022 × 10²³ atoms) = 0.06642 mol

Answer:

the answer is D.)

Explanation:

Answer:

Positively charged ions are called cations; negatively charged ions, anions

Answer:

for 1 solid its freezing.

for 2 solid and liquid its melting

for 6 liquid to gas its evaporation and for 5 gas  to liquid its condensation.

Explanation:

hope this helped :)

Answer:

solid->liquid= melting

liquid->solid= freezing

gas->liquid= consendation

liquid->gas= evaporation

Answer:

Work done W = -382,206 J (Approx)

Explanation:

We know that;

1 atm = 101.32 kPa

1 L-atm = 101.325 J

1 m³ = 1,000 L

Computation:

Work done W = -P∆V

Pressure = 196 kPa × (1 / 101.32 kPa)

Pressure = 1.9344 atm

∆V = 1.95 × (1000 L) = 1,950 L

So,

W = -(1.9344 atm) × (1,950 L)

W = -3772.0 L-atm

Work done W = -3772.0 L-atm × (101.325 J / 1 L.atm)

Work done W = -382,206 J (Approx)

The work done by the gas in Joules is equal to 3,763.5‬ Joules.

Given the following data:

Conversion:

1 atm = 101.325

X atm = 196.0 kPa

X = [tex]\frac{196.0}{101.325} = 1.93\; atm[/tex]

Conversion:

1 [tex]m^3[/tex] = 1000 Liter

1.95 [tex]m^3[/tex] = 1950 Liter

To calculate the work done by the gas in Joules:

Mathematically, the work energy by a system is given by the formula:

[tex]Work = P \delta V[/tex]

Where:

Substituting the parameters into the formula, we have

[tex]Work\;energy = 1.93 \times 1950[/tex]

Work energy = 3,763.5‬ Joules.

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Answer:speed of 6.5 meters per second, what is the distance she covers in that time? ... backstrokes at an average speed of 8 meters per second, how long will it take ... 200m smis. 255. 7. Lauren's SUV was detected exceeding the posted speed limit ... Suppose the polar bear was running on land instead of swimming. ... V = 8.3mls.

Explanation:

[tex]\mathfrak{\huge{\pink{\underline{\underline{AnSwEr:-}}}}}[/tex]

Actually Welcome to the Concept of the Kinematics.

Since, we know that,

Time = Distance / Speed

so here, Speed = 8.3 m/s and Distance= 200m

so we get as, T = 200/8.3 => 24.09 seconds.

Hence, time taken will be => 24.09 seconds.

Answer:

Joule

Explanation:

Answer:

The calorie

Explanation: as the amount of thermal energy necessary to raise the temperature of one gram

Answer:

This question appears incomplete

Explanation:

This question appears incomplete because the data provided only makes it possible to calculate the certainty of the acetic acid content per total volume of the vinegar. Thus, the 4% means for every 100 mL of the vinegar, there is 4 mL of acetic acid present. To calculate the volume of acetic acid in any other volume of vinegar, the formula will be

volume of acetic acid = 4/100 × total volume of vinegar

Answer:

it becomes a negstive charge

Answer:

pH = 2.18

Explanation:

Perchloric acid (HClO₄) is a strong acid. This means that in an aqueous solution it completely dissociates into H⁺ and ClO₄⁻ species.

First we convert 249 mg HClO₄ into moles, using its molecular weight:

Because it is a strong acid, 2.49 mmol HClO₄ = 2.49 mmol H⁺

We calculate the molar concentration of H⁺:

Finally we calculate the pH of the solution:

Answer:

C aq

Explanation:

Means desolves in water

When NaCl is dissolved in water, it separates into its constituent ions Na+ and Cl- ions. The phase of the ions are written as (aq) and that of NaCl is written as (s) .

Sodium chloride is an ionic compound formed by the transfer of electrons from the metal sodium to the nonmetal chlorine. It is used as the common table salt.

Na contains  one valence electron and Cl contains 7 valence electrons. Hence, Na can donate that electron to Cl to achieve octet in both. When Na loss an electron it forms Na+ and Cl gains the electron to form Cl-. These two ions are then attracts to form the NaCl.

When NaCl is dissolved in water the bond between these two ions weaken and the ions gets released  into the solution. The ions in the solution is indicated with the phase aqueous (aq) and the undissolved NaCl is in solid (s) state.

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Answer:

A pure substance made up of two or more elements that are chemically combined is a compound

Explanation:

Answer:

Combustion reaction

General Formulas and Concepts:

Chemistry

Explanation:

Step 1: Define

2C₂H₂ + 5O₂ → 2H₂O + 4CO₂

Step 2: Identify

Any organic molecule reacting with oxygen to produce water and carbon dioxide is a combustion reaction.

We also see from the RxN that is is a double replacement reaction.

Answer:

Answer: 0.4 g

Explanation:

1) Balanced chemical equation:

2) 2C2H2 + 5 O2 → 4CO2 + 2 H2O

3) mole ratios:

2 mol C2h2 : 5 mol O2

4) Convert 0.13 g C2H2 into number of moles

n = mass in grams / molar mass

molar mass C2H2 = 2 *12g/mol + 2*1 g/mol = 26 g/mol

n = 0.13 g / 26 g/mol = 0.005 mol

5) Set the proportion with the unknown

5 mol O2             x

----------------- = ---------------

2 mol C2H2      0.005 mol C2H2

x = 0.005 mol C2H2 * 5 mol O2 / 2 mol C2H2 = 0.0125 mol O2

6) Convert 0.0125 mol O2 to grams

mass = number of moles * molar mass

molar mass of O2 = 32 g/mol

mass = 0.0125 mol * 32 g/mol = 0.4 g

Answer: 0.4 g

Explanation:

Answer:

133.33 g/mol

Explanation:

Molar mass:

Molar is the sum of all the atomic masses of the atoms of the elements present in a compound.

Molar mass of AlCl₃:

Atomic mass of Al = 26.98 amu

Atomic mass of chlorine = 35.45 amu

There are 3 atoms of chlorine present.

35.45×3 = 106.35

Molar mass of AlCl₃ = 26.98  + 106.35  = 133.33 g/mol

The molar mass of AlCl₃ is 133.33 g/mol.

Molar mass of many compounds can be calculated by dividing the mass of the compound by the number of moles of the compound.

Atomic mass of Al = 26.98 amu

Atomic mass of chlorine = 35.45 amu

There are 3 atoms of chlorine present.

35.45 × 3 = 106.35

Molar mass of AlCl₃ = 26.98  + 106.35  = 133.33 g/mol

Thus, the molar mass of AlCl₃ is 133.33 g/mol.

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Answer:

The easy way to do this is to assume the number of moles. Make it a number easily divided by both 2 and 3, so say 6. Now you can have numbers to plug in to Graham's Law to find the second rate, then use the second rate to find the time. Does that make sense?

Answer:

An example of the thermal energy of a substance being decreased is with our food. With the thermal energy of food being decreased it is easier for foods to be eaten comfortably without any damage to the tongue or alimentary canal.

Another good example is in the handling of hot objects in the home. Thermal energy decrease in objects such as iron, pots etc helps to prevent serious burns and injuries.

Answer:

Water turning into ice

juice frozen to make popsicles

Explanation:

When something goes from liquid to a solid, that is a process called freezing. When a object loses thermal energy the particles move slower forming a solid.

Answer:

3.34 x 1023 atoms

Explanation:

11.12 grams of sodium chloride is required to prepare 380 mL of 0.500 M NaCl (MW = 58.5 g/mol).

HOW TO CALCULATE MASS:

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Answer:

[tex]m_w=439.2g[/tex]

Explanation:

Hello!

In this case, since the by-mass percent of a solution is a measure of the mass of the solute over the mass of the solution:

[tex]\%m/m=\frac{m_{solute}}{m_{solution}} *100\%[/tex]

As we know the mass of the solution and the by-mass percent, we can compute the mass of glucose in the 480 g of solution:

[tex]m_{solute}=\frac{\%m/m*m_{solution}}{100\%}[/tex]

Thus, by plugging in the data, we obtain:

[tex]m_{solute}=\frac{8.5\%*480g}{100\%}=40.8g[/tex]

Finally, since the solution is made up of glucose and water, we compute the mass of water as follows:

[tex]m_w=m_{sol}-m_{solute}=480g-40.8g\\\\m_w=439.2g[/tex]

Best regards!

Answer:

Chemical change

Explanation:

The rusting of iron/a nail is a chemical change

Iron (Fe) and Oxygen (O) combine to create the compound Iron Oxide (Fe2O3), which is rust.