A combustion reaction will always be associated with a change in entropy that will be positive.
What is entropy ?The entropy of a system is the measurement of the disorder of the system which happens in the thermodynamic reaction.
During association the value of entropy will be positive and during dissociation the value will be negative.
During association the number of molecule increases due to which the entropy of the combustion increases and the value will be positive .
Therefore , combustion reaction will always be associated with a change in entropy that will be positive.
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Calculate the number of molecules in 1500 mL of a gas measured under a pressure of 800.0
torr at 19.0°C
Answer:
3.97 x 10²² molecules
Explanation:
To find the moles, you need to use the Ideal Gas Law:
PV = nRT
In this equation,
-----> P = pressure (atm)
-----> V = volume (L)
-----> n = moles
-----> R = Ideal Gas constant (0.08206 atm*L/mol*K)
-----> T = temperature (K)
Before you can plug the values into the equation, you need to (1) convert the pressure from torr to atm (by dividing by 760), then (2) convert the volume from mL to L (by dividing by 1000), and then (3) convert the temperature from Celsius to Kelvin (by adding 273).
P = 800.0 torr / 760 = 1.05 atm R = 0.08206 atm*L/mol*K
V = 1500 mL / 1000 = 1.5 L T = 19.0 °C + 273 = 292 K
n = ? moles
PV = nRT
(1.05 atm)(1.5 L) = n(0.08206 atm*L/mol*K)(292 K)
1.579 = n(23.96)
0.0659 = moles
Now, you need to convert moles to molecules using Avogadro's Number.
Avogadro's Number:
6.022 x 10²³ molecules = 1 mole
0.0659 moles 6.022 x 10²³ molecules
------------------------ x ------------------------------------- = 3.97 x 10²² molecules
1 mole
Compute the theoretical density of zns given that the zn-s distance and bond angle are 0. 234 nm and 109. 5o, respectively? The atomic weights of zinc and sulfur are 65. 41 g/mol and 32. 06 g/mol.
Density of ZnS given that the zn-s distance and bond angle are 0. 234 nm and 109. 5o, respectively if the atomic weights of zinc and sulfur are 65. 41 g/mol and 32. 06 g/mol. is 4.1109 g/cm³
For density In the crystal structure, we determine the angle's value for one set of ZnS bonds. θ θ + ∅ + 90° = 180° θ = 90° - ∅ θ = 90° - (109.5° / 2) After determining that = 35.25°, we derive the value of x from the geometry: distance angle d = 0.234 x = dsin = 0.234 sin35.25°) = 0.135 nm = 0.135 107 cm; following this, we get the length of the unit cell: a = 4x a = 4(0.135) a = 0.54 nm = 0.54 107 cm; and The formula for n' is (number of corner atoms in unit ell contribution of each corner atom in unit cell) + (number of face center atoms in unit cell contribution of each face center atom in unit cell). n' = 8 × 1/8) + (6 × 1/2) = 1 + 3 = 4
Density = P = [4( 65.41 + 32.06)] / [ ( 0.54 × 10⁻⁷ )³ × (6.023 × 10²³)] = 389.88 / 94.84 = 4.1109 g/cm³
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Suppose that 25. 0 ml of 0. 10 m ch3cooh(aq) ( ka =1. 8 x 10-5) is titrated with 0. 10 m naoh(aq). (a)what is the initial ph of the 0. 10 m ch3cooh (aq) solution?
The initial ph of the 0. 10M ch3cooh (aq) solution is -0.64.
The salt sodium acetate is present at the equivalency point. It is a salt of a strong base and a weak acid. The expression "its pH" provides the information.
pH = 7 + 0.5p + 0.5logC
where C is the salt concentration. Monobasic acid is Acetic acid here.
25 ml of 0.10 M NaOH solution are needed for the titration of 25 ml of 0.10 M acetic acid.
Total volume = 25 + 25 = 50ml
The salt concentration = C = 0.10× = 0.05
The pH for weak acid is given by,
pH = [tex]\frac{1}{2}[/tex] (p[tex]K_{a}[/tex] + logC)
pH = [tex]\frac{1}{2}[/tex] (1.8× + log0.05)
pH = [tex]\frac{1}{2}[/tex] [1.8× + (-1.30)]
pH = [tex]\frac{1}{2}[/tex] (1.8× -1.30)
pH = -0.64
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If 30. 0 ml of 0. 150 m CaCl2 is added to 15. 0 ml of 0. 100 m AgNo3, what is the mass in grams of AgCl precipitate?
The mass of AgCl precipitated is 0.215g.
What do you mean by precipitation?Precipitate is to form an insoluble compound either by reacting two salts or by changing the temperature to affect the solubility of the compound.
To calculate mass of AgCl precipitate -
The first step is to make a balanced chemical equation.
2AgNO3 + CaCl2 ---> 2AgCl + Ca(NO3)2
Molecular Weights:
CaCl2 = 110.98 g/mol
AgNO3 =170.01g/mol
AgCl= 143.45 g/mol
Volume:
CaCl2: 30.0mL=0.03L
AgNO3: 15.0mL=0.015 L
mole CaCl2 = 30/1000 x 0.2 =0.006
mole AgNO3 =15/1000 x 0.1 = 0.0015
CaCl2 is in excess so 0.0015 mole AgCl will form
0.0015 x 143.5 = 0.215g
The 0.215 mass in grams of AgCl will precipitate.
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The pH of an aqueous solution is determined to be 3. What is the hydronium ion concentration of the
solution?
A. [H3O+] = 1 x 10-³ M
B. [H3O+] = 3 x 10-³ M
[H3O+] = 1 x 10-11 M
D. [H3O+] = 3 x 10-11 M
Considering the definition of pH, the hydronium ion concentration [H₃O⁺] of the solution is 1×10⁻³ M.
Definition of pHpH is the Hydrogen Potential. It is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance.
Mathematically, pH is calculated as the negative base 10 logarithm of the activity of hydrogen ions:
pH= - log [H⁺]= -log [H₃O⁺]
The numerical scale that measures the pH of substances includes the numbers from 0 to 14. The pH value 7 corresponds to neutral substances. Acidic substances are those with a pH lower than 7, while basic substances have a pH higher than 7.
Hydronium ion concentrationIn this case, being pH= 3, you can replace this value in the definition of pH:
3= -log [H₃O⁺]
Solving:
[H₃O⁺]= 10⁻³ M
[H₃O⁺]= 1×10⁻³ M
Finally, the hydronium ion concentration [H₃O⁺] of the solution is 1×10⁻³ M.
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The molar solubility of cui is 2. 26 × 10-6 m in pure water. Calculate the ksp for cui.
Ksp(the solubility product constant) = [Cu⁺] [I⁻]
So, the Ksp for Cui would be:
Ksp = (2.26 × 10⁻⁶) (2.26 × 10⁻⁶) = 5.11 x 10⁻¹²
Formula used:
K = [tex]K_{sp} = [A^+]^a [B^-]^b[/tex], where
Ksp = solubility product constant
A⁺ = cation in an aquious solution
B⁻ = anion in an aqueous solution
a, b = relative concentrations of a and b
DefinitionThe equilibrium constant for a solid material dissolving in an aqueous solution is the SOLUBILITY PRODUCT CONSTANT, Ksp. It stands for the degree of solute dissolution in solution. A substance's Ksp value increases with how soluble it is.
Take into account the general dissolving response (in aqueous solutions) below:
aA(s)⇔cC(aq)+dD(aq)
The molarities or concentrations of the products (cC and dD) must be multiplied in order to find the Ksp. Any product that has a coefficient in front of it must be raised to the power of that coefficient (and also multiply the concentration by that coefficient).
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If the rock had originally 2400 atoms of u 235 and now has 440 left, how many atoms of pb 207 are there in the rock now?
436 atoms of Pb 207 are left in the rock.
Radioactive decay:Alpha and beta decays are the mechanism through which uranium transforms into the lead. While 235U and its daughter nuclides only experience seven alpha and four beta decays, 238U and its daughter nuclides suffer eight alpha and six beta decays overall.
When there are too few neutrons in relation to protons, alpha decay occurs. There is the discharge of an alpha particle, which consists of two protons and two neutrons.
When there are more neutrons than protons, beta decay can happen. A high-speed electron is ejected from a proton that transforms spontaneously from a neutron.
Since gamma radiation is emitted as a wave rather than a particle, the atomic structure of an atom remains unaltered. Atomic fission is the primary cause of neutron emission. At one time, many neutrons can be released.
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A 1. 3×10−6mol sample of sr(oh)2 is dissolved in water to make up 25. 0 ml of solution. what is the ph of the solution at 25. 0∘c?
The pH of the solution at 25 degree celsius of 1.3 × 10⁻⁶ moles of a sample of Sr(OH)₂ is 10.02.
How do we calculate pH?The pH of any solution gives an idea about the acidic and basic nature of the solution and the equation of pH will be represented as:
pH + pOH = 14
Given that,
Moles of Sr(OH)₂ = 1.3 × 10⁻⁶ mol
Volume of solution = 25mL = 0.025L
The concentration of Sr(OH)₂ in terms of molarity = 1.3×10⁻⁶/0.025
= 5.2×10¯⁵M
Dissociation of Sr(OH)₂ takes place as:
Sr(OH)₂ → Sr²⁺ + 2OH⁻
From the stoichiometry of the reaction 1 mole of Sr(OH)₂ produces 2 moles of OH⁻.
Given that the base is a strong base and that it entirely dissociates into its ions, the hydroxide ion concentration is 5.2×10¯⁵×2 = 1.04×10¯⁴ M.
pOH = -log[OH⁻]
pOH = -log(1.04×10¯⁴)
pOH = 3.98
Now we put this value on the first equation we get,
pH = 14 - 3.98 = 10.02
Therefore, the value of pOH is 10.02.
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What was the average molarity of the sodium hydroxide solution obtained from your two fine titrations?
Divide the number of moles of NaOH by the number of liters of NaOH solution needed to reach the titration's endpoint to determine the molarity of the NaOH solution.
"The process of calculating the quantity of a material A by adding measured increments of substance B, the titrant, with which it reacts until exact chemical equivalency is obtained (the equivalence point)" is the definition of titration.
Titration is a method of chemical analysis where the amount of a sample's ingredient is determined by adding an exact known amount of a different substance to the measured sample in which the desired constituent interacts in a specific, known proportion.
The equivalence point, or the point at which chemically equivalent amounts of the reactants have been combined, is to be detected by the titration. The stoichiometry of the reaction determines how many reactants have been combined at the equivalence point.
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