What is matter mad of?

uranmaximum [27]

Answer: - 25.8 kJ

The overall process of interest in the question is the following

Hg (g) (650 K) → Hg (l) (297 K)

However, for mercury to pass from a gaseous state in 650 K to a liquid state in 297 K, it must go through a series of steps:

Step 1. Gaseous mercury at 650 K should cool down to 629.88 K, temperature corresponding to the vaporization temperature of this substance.

Step 2. Gaseous mercury goes to liquid state at 629.88 K .

Step 3. The liquid mercury at 629.88 K is cooled until it reaches 297 K.

This series of steps can be represented through the following diagram:

Hg (g) (650 K) → Hg (g) (629.88 K) → Hg (l) (629.88 K) → Hg (l) (297 K)

(1) (2) (3)

Then the total heat involved in the process will be equal to the sum of the heats inherent to steps 1, 2 and 3. We proceed to calculate the heats for each of the steps.

Step 1:

The heat in step 1 will be given by

Q = n Cp ΔT

where n is the number of moles of mercury, Cp is the heat capacity and ΔT is equal to the difference between the temperatures at the end (T₂) and at the beginning of the process (T₁), that is to say

ΔT = T₂ - T₁

You should know that the heat capacity or thermal capacity is the energy needed to increase the temperature of a certain substance in a unit of temperature. The heat capacity of mercury is Cp = 27.983 J / mol K

Then the heat in step 1 will be,

Q₁ = 75.0 g x $\frac{1 mol}{200.59 g}$ x 27.983 $\frac{J}{mol K}$ x (629.88 K - 650 K)

→ Q₁ = - 210.5 J

Step 2:

In this step a change in the state of the mercury occurs, since it condenses from a gaseous state to a liquid state. In this case the heat involved in the process will be given by ,

Q = - n ΔHvap

where ΔHvap is the enthalpy of vaporization. The enthalpy of vaporization is the amount of energy necessary for the mass unit of a substance that is in equilibrium with its own vapor at a pressure of one atmosphere to pass completely from the liquid state to the gaseous state. Therefore, to determine the energy necessary for the mercury to pass from gaseous state to liquid, the negative of the enthalpy of vaporization must be taken, as it is done in the previous equation with the minus sign that is placed.

The enthalpy of vaporization of mercury is ΔHvap = 59.11 kJ/mol

Then the heat in step 2 will be,

Q₂ = - 75.0 g x $\frac{1 mol}{200.59 g}$ x 59.11 $\frac{kJ}{mol}$

→ Q₂ = 22.10 kJ → Q₂ = 22100 J

Step 3:

The heat in step 3 will be

Q₃ = n Cp ΔT = 75.0 g x $\frac{1 mol}{200.59 g}$ x 27.983 $\frac{J}{mol K}$ x (297 K - 629.88 K)

→ Q₃ = - 3483 J

Finally the heat involved in the overall process will be ,

Q = Q₁ + Q₂ + Q₃ = - 210.5 J - 22100 J - 3483 J = - 25794 J

→ Q = - 25.8 kJ

So, the heat lost when 75.0 g of mercury vapor at 650 K condenses to a liquid at 297 K is - 25.8 K

3 0

3 years ago

Phosphoric acid is a polyprotic acid. Write balanced chemical equations for the sequence of reactions that phosphoric acid can u

Lesechka [4]

Phosphoric acid is a polyprotic acid. Write balanced chemical equations for the sequence of reactions that phosphoric acid can undergo when it's dissolved in water is given below

Explanation:

Many acids contain two or more ionizable hydrogens. There are two in carbonic acid, H₂CO₃, and three in phosphoric acid, H ₃PO ₄. For any such multiple hydrogen acid, the first hydrogen is most easily removed, and the last hydrogen is removed with the greatest difficulty. These acids are called polyprotic (many protons) acids. The multiple acid ionization constants for each acid measure the degree of dissociation of the successive hydrogens.

Step 1

Polyprotic acid is an acid that can donate two or more H+ ion per molecule. Sulfurous acid donates two hydrogen ions in an aqueous solution.

Step 2

Dissociation of sulfurous acid in aqueous solution takes place in two steps. In the first step, one H⁺ ion is donated during dissociation forming HSO₃⁻.

H₂SO₃₍aq₎ +H₂O₍₁₎→HSO₃⁻₍aq₎

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Step 3

In the second step, one H+ ion is donated from HSO3- ion f...

H₂SO₃₍aq₎ +H₂O₍₁₎→SO₃²⁻₍aq₎+H₃O⁺₍aq₎

5 0

3 years ago

Combustion analysis of 1.200 g of an unknown compound containing carbon, hydrogen, and oxygen produced 2.086 g of CO2 and 1.134

timurjin [86]

the empirical formula is C3H8O2 You need to determine the relative number of moles of hydrogen and carbon. So you first calculate the molar mass of CO2 and H20 Atomic weight of carbon = 12.0107 Atomic weight of hydrogen = 1.00794 Atomic weight of oxygen = 15.999 Molar mass CO2 = 12.0107 + 2 * 15.999 = 44.0087 Molar mass H2O = 2 * 1.00794 + 15.999 = 18.01488 Now calculate the number of moles of CO2 and H2O you have Moles CO2 = 2.086 g / 44.0087 g/mole = 0.0474 mole Moles H2O = 1.134 g / 18.01488 g/mole = 0.062948 mole Calculate the number of moles of carbon and hydrogen you have. Since there's 1 carbon atom per CO2 molecule, the number of moles of carbon is the same as the number of moles of CO2. But since there's 2 hydrogen atoms per molecule of H2O, The number of moles of hydrogen is double the number of moles of H2O Moles Carbon = 0.0474 Moles Hydrogen = 0.062948 * 2 = 0.125896 Now we need to determine how much oxygen is in the compound. Just take the mass of the compound and subtract the mass of carbon and hydrogen. What's left will be the mass of oxygen. Then divide that mass by the atomic weight of oxygen to get the number of moles of oxygen we have. 1.200 - 0.0474 * 12.0107 - 0.125896 * 1.00794 = 0.503797 Moles oxygen = 0.503797 / 15.999 = 0.031489 So now we have a ratio of carbon:hydrogen:oxygen of 0.0474 : 0.125896 : 0.031489 We need to find a ratio of small integers that's close to that ratio. Start by dividing everything by 0.031489 (selected because it's the smallest value) getting 1.505288 : 3.998095 : 1 The 1 for oxygen and the 3.998095 for hydrogen look close enough. But the 1.505288 for carbon doesn't work. But it looks like if we double all the numbers, we'll get something close to an integer for everything. So do so. 3.010575 : 7.996189 : 2 Now this looks good. Rounding everything to an integer gives us 3 : 8 : 2 So the empirical formula is C3H8O2

5 0

3 years ago

What are the answer??

MrMuchimi

Answer:?

Explanation:None

4 0

3 years ago

I don't know any things

d1i1m1o1n [39]

A cell is made of molecules and a molecule is made of atoms. That's the simplest way of putting it. More complicated is that a cell is made up of macromolecules, such as proteins, lipids, etc. A molecule is a particular configuration of atoms.

4 0

4 years ago

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