Answer:
See explanation
Explanation:
The ability of a hydride to act as a reducing agent depends on the electro negativity of the central atom in the complex hydride anion.
If we compare the electronegativities of Boron and Aluminum, Boron is more electronegative than aluminum. The more electronegative the central atom is, the lesser the electron density on the hydride and the lesser its ability to act as a reducing agent.
For the reason stated above, LiAlH4, having aluminium of low electro negativity as its central atom is a better reducing agent than NaBH4.
Which of the following factors has no effect on the rate of SN1 reactions?a. the nature of the alkyl halide. b. the nature of the leaving group c. the concentration of the alkyl halide d. the concentration of the nucleophile e. the value of the rate constant
Answer:
the concentration of the nucleophile
Explanation:
In an SN1 mechanism, the rate determining step is the formation of the carbocation. The nucleophile does not appear in the rate equation because the rate determining step is unimolecular and entirely depends on the concentration of the alkyl halide.
Hence, the concentration of the nucleophile has no effect on the rate of an SN1 reaction because the rate determining step involves only the alkyl halide.
The factor which has no effect on the rate of SN¹ reaction is the concentration of the nucleophile.
What is SN¹ reaction?SN¹ reaction is known as unimolecular nucleophilic reaction, which is completed in two steps.
First step in the SN¹ reaction is the rate determining step i.e. that step determines the rate of reaction. And in this step formation of carbocation takes place because of the loss of leaving group from the reactant. So, rate of reaction is not depends on the concentration of attacking nucleophile.
Hence, option (d) is correct.
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Identify the predominant intermolecular forces in each of these substances.
1. H2O
2. CaCl2
3. CH3CH(CH3)OH
4. CH4
5. NH3
Answer:
H2O- hydrogen bonding
CaCl2- ion-ion interaction
CH3CH(CH3)OH- hydrogen bonding
CH4- dispersion forces
NH3- hydrogen bonding
Explanation:
Intermolecular forces are secondary bond forces that hold the molecules of a substance together in a given state of matter.
Intermolecular forces account for quite a number of the observed physical properties of a substance such as the boiling and melting point.
If a compound contains hydrogen atom bonded to a highly electronegative element, hydrogen bonding becomes the most dominant intermolecular force, e.g in water and ammonia.
For nonpolar molecules, dispersion forces are the most dominant intermolecular forces. In ionic substance, ion-ion interaction becomes quite prominent.
How does ionization of a given molecule affect its distribution between the organic and aqueous layer
Answer:
Ionized molecules will be found in the aqueous layer
Explanation:
The principle of solvent extraction involves the partitioning of a substance between an aqueous layer and an organic layer. The aqueous layer is polar in nature while the organic layer is nonpolar in nature.
All nonpolar substances are found in the organic layer while all polar substances are found in the aqueous layer. Hence, in the aqueous phase, the following species can be found; positive ions, negative ions and neutral polar molecules or ionic substances.
In which of the following groups of substances would dispersion forces be the only significant factors in determining boiling points? I. Cl2 II. HF III. Ne IV. KNO2 V. CCl4
Answer:
Cl2,Ne, CCl4
Explanation:
Dispersion forces are quite significant as the predominant intermolecular forces in nonpolar substances. For Cl2,Ne and CCl4, dispersion forces are the primary kind of intermolecular interaction present in the compound.
Hence, the boiling point of these substances will be determined solely by the dispersion forces between the molecules.
Cl2, Ne, CCl4 are the group of substances in which dispersion forces would
help determine the boiling point.
Dispersion force is a type of Van der waals force and is also regarded as
London forces. This type of force occur between the atoms and molecules
when electrons are symmetrically distributed in the nucleus.
This force is a weak intermolecular force and is present in non polar
compounds such as Cl2, Ne, CCl4 . KNO2 is polar and hence doesn't
determine its boiling point.
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Convert 0.00000000045 to scientific notation.
Answer:
4.5 multiplied by 10, to the -10th power.
[tex](4.5 \times 10 { - }^{10} )[/tex]
Which of the following equilibria would not be affected by pressure changes at constant temperature?
A) CO(g) + 1/2O2(g) CO2(g).
B) CaCO3(s) CaO(s) + CO2(g).
C) 2H2(g) + O2(g) 2H2O(l).
D) 2Hg(l) + O2(g) 2HgO(s).
E) CO2(g) + H2(g) CO(g) + H2O(g).
Answer:
Option A) CO(g) + 1/2O2(g) <=> CO2(g).
Explanation:
A background knowledge of reaction rates shows that pressure will only affect gaseous reactant.
Further more, we understood that for pressure to effectively affect gaseous molecules, the total volume of the gaseous reactant must be different from the total volume of the gaseous products.
Now, let us consider the equation given in the question:
A) CO(g) + 1/2O2(g) <=> CO2(g).
B) CaCO3(s) <=> CaO(s) + CO2(g).
C) 2H2(g) + O2(g) <=> 2H2O(l).
D) 2Hg(l) + O2(g) <=> 2HgO(s).
E) CO2(g) + H2(g) <=> CO(g) + H2O(g).
From the above, only option A and E has gaseous reactant and product.
For option A:
CO(g) + 1/2O2(g) <=> CO2(g).
Total volume of reactant = 1 + 1/2 = 3/2 L
Total volume of product = 1 L
Since the volume of the reactant and that of the product are different, therefore, a change in pressure will affect the reaction.
For option E:
CO2(g) + H2(g) <=> CO(g) + H2O(g).
Total volume of reactant = 1 + 1 = 2 L
Total volume of product = 1 + 1 = 2 L
Since the volume of the reactant and that of the product are the same, therefore, a change in pressure will have no effect in the reaction.
The equilibrium equation, CO2(g) + H2(g) ⇄ CO(g) + H2O(g), is not affected by pressure changes at constant temperature because there are equal volumes of reactants and products on both sides of reaction equation.
For a gas phase reaction, changes in pressure would affect the direction in which the reaction moves. When the pressure is increased, the reaction moves in the direction of lesser volumes. When the pressure is decreased, the reaction moves in the direction of greater volumes.
For the reaction; CO2(g) + H2(g) ⇄ CO(g) + H2O(g), there are equal volumes of reactants and products on either side of the reaction equation. Therefore, the equilibria would not be affected by pressure changes at constant temperature.
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At 25°C, an aqueous solution containing 35.0 wt% H2SO4 has a specific gravity of 1.2563. A quantity of the 35% solution is needed that contains 195.5 kg of H2SO4.
A) Calculate the required volume (L) of the solution using the given specific gravity.
B) Estimate the percentage error that would have resulted if pure-component specific gravities of H2SO4 (SG = 1:8255) and water had been used for the calculation instead of the given specific gravity of the mixture.
Answer:
a) volume₁ = 444.6 L
b) Volume₂ = 306 L and percentage Error = 31.2%
Explanation:
Given that;
the solution contains 35.0 wt% H₂SO₄
A quantity of the 35% solution is needed that contains 195.5 kg of H₂SO₄
Lets say mass of solution containing 195.5 kg H₂SO₄ is 'A' kg
Now since the question saysm it is a 35% wt solution,
so
(35/ 100) × Akg = 195.5kg
0.35A = 195.5
A = 558.6kg
So A = 558.6 kg
therefore mass of the solution is 558.6kg
a)
also Specific gravity is 1.2563
since density of water = 1kg/ L
density of solution = SG of H₂SO₄ × density of water
therefore density of solution = 1.2563 ×1kg/ L = 1.2563 kg/ L
Now to calculate the required volume (L) of the solution
we say;
Volume of solution = mass / density
Volume = 558.6kg / 1.2563kg/L
Volume₁ = 444.6 L
b)
Now If pure-component specific gravity is to be used,
Specific Gravity = 1.8255
which means Density will be = 1.8255 kg/ L
Therefore will be
Volume = 558.6kg / 1.8255kg/L
Volume₂ = 306 L
To calculate the error
we say volume₁ - volume₂
Error = 444.6L - 306L = 138.6
So
Percent error = ( 138.6L / 444.6L) × 100
percentage Error = 31.2%
Convert a speed of 857 mi/h to units of feet per minute. Also, show the unit analysis by dragging components into the
unit-factor slots.
Answer Bank
857 mi
х
1 h
f)x()
1 min
60 s
12 in
60 min
1 mi
3 ft
1 h
60 h
5280 ft
1 ft
857 mi/h =
ft
min
Answer:
The answer would be 75,416 feet / minute.
And the conversion would be: 857 miles / 1 h = (1h / 60 minutes) (5280 feet / 1 mile)
Explanation:
Conversion factors are mathematical operations used to make unit changes of the same magnitude, in magnitudes of weight, time, or length. etc.
It consists of multiplying one or more fractions several times in which the numerator and the denominator are equal quantities expressed in different ways.
For example: 1 hour = 60 minutes = 3600 seconds.
857 miles / 1 hr = (1h / 60 minutes) (5280 feet / 1 mile)
When looking at the equilibrium between silver bromide and its aqueous ions, what could be added to solution to promote precipitation of silver bromide?
Answer:
NaBr
Explanation:
When AgBr is dissolved in water, the following equilibrium is set up in solution;
AgBr(s)⇄Ag^+(aq) + Br^- (aq)
If we dissolve NaBr in the water, a common ion (Br^-) is now introduced into the system. This increases the concentration of Br^- and favours the reverse reaction hence more AgBr is precipitated. This is known as common ion effect.
What is the stoichiometric coefficient for oxygen when the following equation is balanced using the lowest whole-number coefficients? C3H6O2(l) + O2(g) → CO2(g) + H2O(l)A) 5 B) 7 C) 1 D) 3
Answer:
Option (B) 7
Explanation:
C3H6O2(l) + O2(g) → CO2(g) + H2O(l)
To know the coefficient of O2 in the above equation, let us balance the equation.
The above equation can be balance as follow:
C3H6O2(l) + O2(g) → CO2(g) + H2O(l)
There are 3 atoms of C on the left side and 1 atom on the right side. It can be balance by putting 3 in front of CO2 as shown below:
C3H6O2(l) + O2(g) → 3CO2(g) + H2O(l)
There are 6 atoms of H on the left side and 2 atoms on the right side. It can be balance by putting 3 in front of H2O as shown below:
C3H6O2(l) + O2(g) → 3CO2(g) + 3H2O(l)
There are a total of 4 atoms of O on the left side and a total of 9 atoms on the right side. It can be balance by putting 7/2 in front of O2 as show below:
C3H6O2(l) + 7/2O2(g) → 3CO2(g) + 3H2O(l)
Multiply through by 2
2C3H6O2(l) + 7O2(g) → 6CO2(g) + 6H2O(l)
Now, the equation is balanced.
From the balanced equation above, the coefficient of O2 is 7.
What is the pH of a 0.1 M solution of acetic acid (pKa = 4.75)?
Answer:
[tex]pH=2.88[/tex]
Explanation:
Hello,
In this case, since dissociation of acetic acid is:
[tex]CH_3COOH\rightleftharpoons CH_3COO^-+H^+[/tex]
The equilibrium expression in terms of the acid dissociation constant is:
[tex]Ka=\frac{[CH_3COO^-][H^+]}{[CH_3COOH]}[/tex]
In such a way, in terms of the reaction extent, we write:
[tex]Ka=\frac{x*x}{0.1-x}[/tex]
And Ka is computed from the pKa:
[tex]Ka=10^{-pKa}=10^{-4.75}=1.78x10^{-5}[/tex]
[tex]1.78x10^{-5}=\frac{x*x}{0.1-x}[/tex]
Thus, solving for [tex]x[/tex] we obtain:
[tex]x=0.001325M[/tex]
Which is also equal to the concentration of H⁺ so the pH is:
[tex]pH=-log(0.001325)\\\\pH=2.88[/tex]
Regards.
why is the concentration of a solid left out of the equilibrium expression for the solubility of a salt
Answer:
Its concentration remains constant
Explanation:
The concentration of a pure solid is left out of the expression for the equilibrium solubility of a salt because the concentration of a pure solid remains constant. Therefore, the activity of a pure solid is 1.
Being of a constant concentration, the pure solid is not included in equilibrium expression for the solubility of a salt.
A sample of ammonia gas was allowed to come to equilibrium at 400 K. 2NH3(g) <---> N2(g) 3H2(g) At equilibrium, it was found that the concentration of H2 was 0.0551 M, the concentration of N2 was 0.0183 M, and the concentration of NH3 was 0.383 M. What is Kc for this equilibrium
Answer:
Kc for this equilibrium is 2.30*10⁻⁶
Explanation:
Equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction and the concentrations of reactants and products are held constant.
Being:
aA + bB ⇔ cC + dD
the equilibrium constant Kc is defined as:
[tex]Kc=\frac{[C]^{c}*[D]^{d} }{[A]^{a} *[B]^{b} }[/tex]
In other words, the constant Kc is equal to the multiplication of the concentrations of the products raised to their stoichiometric coefficients by the multiplication of the concentrations of the reactants also raised to their stoichiometric coefficients. Kc is constant for a given temperature, that is to say that as the reaction temperature varies, its value varies.
In this case, being:
2 NH₃(g) ⇔ N₂(g) + 3 H₂(g)
the equilibrium constant Kc is:
[tex]Kc=\frac{[N_{2} ]*[H_{2} ]^{3} }{[NH_{3} ]^{2} }[/tex]
Being:
[N₂]= 0.0551 M[H₂]= 0.0183 M[NH₃]= 0.383 Mand replacing:
[tex]Kc=\frac{0.0551*0.0183^{3} }{0.383^{2} }[/tex]
you get:
Kc= 2.30*10⁻⁶
Kc for this equilibrium is 2.30*10⁻⁶
Glucagon secretion is stimulated when blood glucose concentration decreases. which carbohydrate pathways does glucagon stimulate in liver?
A. glycogen synthesis (glycogenesis)
B. glycolysis
C. glucose uptake
D. gluconeogenesis
E. glycogenolysis
Answer:
E. glycogenolysis
Explanation:
Glycogenolysis is the process whereby excess glucose stored by the body in the form of glycogen is then converted back/broken down into glucose molecules to serve as a source of energy
Glucagon secretion is stimulated when blood glucose concentration decreases and is secreted by the pancreas. The liver then converts the glycogen into glucose for use by the body
i need to know the measurements of this to the appropriate amount of significant figures
Answer:
[See Below]
Explanation:
25 ml.
Water flows over Niagara Falls at the average rate of 2,400,000 kg/s, and the average height of the falls is about 50 m. Knowing that the gravitational potential energy of falling water per second = mass (kg) × height (m) × gravity (9.8 m/s2), what is the power of Niagara Falls? How many 15 W LED light bulbs could it power?
Answer:
Power, [tex]P=1.176\times 10^9\ W[/tex]
No of bulbs = 78400000
Explanation:
We have,
Water flows over Niagara Falls at the average rate of 2,400,000 kg/s, it mean it is mass per unit time i.e. m/t.
It falls from a height of 50 m
The gravitational potential energy of falling water is given by :
P = mgh
Power is equal to the work done divided by time taken. So,
[tex]P=\dfrac{W}{t}\\\\P=\dfrac{mgh}{t}\\\\P=\dfrac{m}{t}\times gh[/tex]
So,
[tex]P=2400000\times 9.8\times 50\\\\P=1.176\times 10^9\ W[/tex]
Let there are n bulbs that could power 15 W LED. It can be calculated by dividing the power by 15. So,
[tex]n=\dfrac{1.176\times 10^9}{15}\\\\n=78400000\ \text{bulbs}[/tex]
It means that the number of bulbs are 78400000.
What is milk made of?
Answer:
Protein
Explanation:
Answer:
Water, fat, proteins, lactose, and minerals. Milk also contains trace amounts of other substances such as pigments, enzymes, vitamins, phospholipids, and gases.
Describe the movement of molecules in solids, liquids, and gases.Be sure to explain why the molecules move differently in each state of matter.
Answer:
See explanation
Explanation:
The degree of movement of molecules in each not the three different states of matter depends on the arrangement of the molecules.
In a solid, molecules are packed closely together and are held in fixed positions by strong intermolecular forces such that they can only vibrate or rotate about a fixed point.
In liquids, molecules are less closely packed hence they can flow around each other but possess only little kinetic energy. Intermolecular forces in liquids are much lesser than that of solids.
In gases, intermolecular forces are negligible and gas molecules move with a very high velocity and possess high kinetic energy. There are large spaces between gas molecules and they are always in motion.
1. Which of the following is a valid piece of scientific evidence?
a. The amount of snow pack in the mountains
b. The way a piece of music makes you feel
C. How many people like brownies more than cake
d. The color blue being called a calming color
Answer: A
Explanation: The other options are opinions and can vary in the way that people respond
The valid piece of scientific evidence among the options provided is:
a. The amount of snow pack in the mountains
Scientific evidence refers to observations or data that can be objectively measured, tested, and analyzed. The amount of snow pack in the mountains can be quantitatively measured and observed, making it a valid piece of scientific evidence. It can be used to study climate patterns, water availability, and various other scientific phenomena related to snow and mountain ecosystems.
The other options, b. The way a piece of music makes you feel, c. How many people like brownies more than cake, and d. The color blue being called a calming color, involve subjective experiences, personal preferences, and cultural associations rather than empirical observations that can be tested and measured in a scientific context.
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modern commercial airlines are largely made of aluminum, and light and strong metal. But the fact that aluminum is cheap enough that airplanes can be made out of it is a bit of historical luck. before the discovery of the Hall-Heroult process in 1886, aluminum was as rare and expensive as gold. What would happen if airplanes had to be made of steel? The fuselage of a Boeing 787, which can carry 400 passengers, is approximately a hollow aluminum cylinder without ends, 70.7 m long, 6.5 m wide, and 2.5 mm thick. Suppose this fuselage was made of steel (density 7.87 g/cm^{3}) instead of aluminum (density 2.7g/[tex]cm^{3}), and let's say the average passenger has a mass of 81 kg. We'll also assume the engines can't lift any greater mass than they already do. Calculate the number of passengers that the Boeing 747 could carry if its fuselage was made of steel.
Answer:
170 passenger . ( approx )
Explanation:
Total volume of metal making fuselage = π ( r₂² - r₁² ) l
r₂ is outer radius of cylindrical tube like fuselage
= 6.5 / 2 + .0025 = 3.2525 m
r₁ is inner radius of cylindrical tube like fuselage
= 6.5 / 2 = 3.25 m
l = 70.7 m
Total volume of fuselage = π ( r₂² - r₁² ) l
= 3.14 x 70.7 x ( 3.2525² - 3.25² )
= 221.998 ( 10.57875 - 10.5625)
= 3.60747 m³
If it is made of aluminium , its mass
= volume x density
= 3.60747 x 2700 kg
= 9740.16 kg
weight of passenger = 81 x 400 = 32400 kg
Total mass = 32400 + 9740.16
= 42140.16 kg
If it is made of iron , its mass
= volume x density
= 3.60747 x 7870 kg
= 28390.79 kg
If number of passenger required be n
81 n + 28390.79 = 42140.16 ( as per condition given )
n = 170 passenger . ( approx )
In the reaction: CH 3COOH(aq) + NH 2 – (aq) CH 3COO – (aq) + NH 3(aq), the conjugate acid-base pairs are:
Answer: CH3COO- & CH3COOH are conjugate
NH2- & NH3 are conjugate
Explanation:
Question 4 of 10
Which question asks for an opinion?
A. How much electricity does the average nuclear power plant
generate?
B. Should the government invest more money in nuclear energy than
in solar energy?
C. What are the by-products generated by the manufacture of solar
panels?
D. How efficient is the most advanced solar energy technology?
Answer:
Should the government invest more money in nuclear energy than
in solar energy
Explanation:
This is because some people might think government should invest in nuclear energy while others might want the government to invest in solar energy.
Answer:
B. "Should the government..."; the answer to this relies on subjective input (what the audience thinks the government should do).
Explanation:
Think about the differences between statements that are subjective and objective. If you look at A, C, or D, these results of these experiments are all objective:
A) The amount of electricity generated by a power plant isn't "arguable"; it's a definite value that I can't just "make up" or "think" is correct/valid.
C) The byproducts generated by manufacture aren't "arguable" either; if a byproduct is heat, there's no subjective input.
D) Try to use the above reasoning for D!
What alkene would give the products below after reaction with O3, followed by reduction with (CH3)2S
The question is incomplete; the complete question is;
What alkene would give the products below after reaction with O3, followed by reduction with (CH3)2S? Write the condensed structural formula (CH3)2C=O and CH3-CH2-CH=O
Answer:
2-methylpent-2-ene (C6H12)
Explanation:
Ozonolysis is a wonderful method for determining the location of double bonds in an alkene since the oxygenated carbons in the carbonyl compounds formed after ozonolysis are the ones that were initially joined by the double bonds in the original alkene.
Hence if an alkene yields (CH3)2C=O and CH3-CH2-CH=O, the original alkene must be C6H12, that is, 2-methylpent-2-ene
For each pair, give the relationship between the two compounds. Making models will be helpful.
(a) (2R, 3S)-2, 3-dibromohexane and (2S, 3R)-2, 3-dibromohexane
(b) (2R, 3S)-2, 3-dibromohexane and (2R, 3R)-2, 3-dibromohexane
Answer:
(a) Enantiomers
(b) Diastereomers
Explanation:
In the first pair of molecules, we have an opposite configuration. That is, in the first molecule we have an R and S configuration and in the second an S and R configuration. Therefore we have a mirror image, if this is true, we will have a mirror image and we will have "enantiomers". (See figure 1)
In the second pair of molecules, we do not have a mirror image. Since the first molecule has an R, S configuration (the mirror image would be S, R). In the second molecule, we have an R, R configuration (the mirror image would be S, S). Therefore, the relationship between these molecules is "diastereoisomers". (See figure 2)
the number of protons in an ato
Answer:
The number of protons in the nucleus of the atom is equal to the atomic number
(Z). The number of electrons in a neutral atom is equal to the number of protons .
The mass number of the atom (M) is equal to the sum of the number of protons
and neutrons in the nucleus.
From this value, and assuming that air contains only molecular nitrogen and molecular oxygen gases, calculate the mass percent of N2 and of O2 in air.
Answer:
60% and 52%
Explanation:
At Standard temperature and volume (STP)
Volume of gas = 22.4L
Density = mass/volume
⇒ 1.186 = [tex]\frac{mass}{22.4}[/tex]
= 26.566g
Molar mass of O2 = 16g/mole
Molar mass of N2 = 14g/mol
% mass of O2 = 16/26.566 × 100
= 60.23 %
% mass of N2 = 14/26.566 × 100
= 52.70 %
(Check: totl composition of gas is 100% i.e 60 + 52 %)
Write the formulas for: Ca and CI, Na and CI, H and 0, Al and 0, and K and F.
Answer:
Below
Explanation:
Combination of Calcium(Ca) and Chlorine(Cl); Calcium chloride
[tex]Ca+Cl_2 -> CaCl_2[/tex]
Combination of Sodium(Na) and Chlorine(Cl); Sodium chloride(salt)
[tex]Na+Cl_2 -> NaCl[/tex]
Combination of Hydrogen(H) and Oxygen(O);(water)
[tex]H_2 +O_2-> H_2O[/tex]
Combination of Potassium (K) and Fluorine(f) ; Potassium fluoride
[tex]K+F ->KF[/tex]
In 1.00 mol of potassium zirconium sulfate trihydrate, K4Zr(SO4)4.3 H20, there are
A
3 x 6.02 x 10 hydrogen atoms
23
B
6.02 x 1023 sulfur atoms
с
4* 6.02 x 1023 potassium atoms
D
4 moles of oxygen atoms
E
4 moles of zirconium atoms
Answer:
C. 4 × 6.02 × 10²³ potassium atoms.
Explanation:
In 1.00 mol of potassium zirconium sulfate trihydrate, K₄Zr(SO₄)₄.3 H₂O, there are
A . 3 × 6.02 × 10²³ hydrogen atoms. NO. There are 3 × 2 moles of hydrogen atoms = 6 moles of hydrogen atoms = 6 × 6.02 x 10²³ hydrogen atoms
B. 6.02 × 10²³ sulfur atoms. NO. There are 4 moles of sulfur atoms = 4 × 6.02 × 10²³ sulfur atoms
C. 4 × 6.02 × 10²³ potassium atoms. YES. There are 4 moles of potassium atoms = 4 × 6.02 × 10²³ potassium atoms
D . 4 moles of oxygen atoms. NO. There are 4 × 4 moles of oxygen atoms = 16 moles of oxygen atoms
E . 4 moles of zirconium atoms NO. There is 1 mole of zirconium atoms
The pH of a solution is 8.83±0.048.83±0.04 . What is the concentration of H+H+ in the solution and its absolute uncertainty?
Answer:
The concentration of [tex]H^{+}[/tex] is 1.48 × [tex]10^{-9}[/tex] M
The absolute uncertainty of [tex][{H^{+}][/tex] is ±0.12 × [tex]10^{-9}[/tex] M
The concentration of [tex]H^{+}[/tex] is written as 1.48(±0.12) × [tex]10^{-9}[/tex] M
Explanation:
The pH of a solution is given by the formula below
pH = [tex]-log_{10}[{H^{+}][/tex]
∴ [tex][H^{+}] = 10^{-pH}[/tex]
where [tex][{H^{+}][/tex] is the [tex]H^{+}[/tex] concentration
From the question,
pH = 8.83±0.04
That is,
pH =8.83 and the uncertainty is ±0.04
First, we will determine [tex][{H^{+}][/tex] from
[tex][H^{+}] = 10^{-pH}[/tex]
[tex][{H^{+}] = 10^{-8.83}[/tex]
[tex][{H^{+}] = 1.4791[/tex] × [tex]10^{-9}[/tex] M
[tex][{H^{+}] = 1.48[/tex] × [tex]10^{-9}[/tex] M
The concentration of [tex]H^{+}[/tex] is 1.48 × [tex]10^{-9}[/tex] M
The uncertainty of [tex][{H^{+}][/tex] ( [tex]U_{[H^{+}] }[/tex] ) from the equation [tex][H^{+}] = 10^{-pH}[/tex] is
[tex]U_{[H^{+}] } = 2.303 \\[/tex] × [tex]{[H^{+}] }[/tex] × [tex]U_{pH }[/tex]
Where [tex]U_{[H^{+}] }[/tex] is the uncertainty of [tex][{H^{+}][/tex]
[tex]U_{pH }[/tex] is the uncertainty of the pH
Hence,
[tex]U_{[H^{+}] }[/tex] = 2.303 × 1.4791 × [tex]10^{-9}[/tex] × 0.04
[tex]U_{[H^{+}] }[/tex] = 1.36 × [tex]10^{-10}[/tex] M
[tex]U_{[H^{+}] }[/tex] = 0.12 × [tex]10^{-9}[/tex] M
Hence, the absolute uncertainty of [tex][{H^{+}][/tex] is ±0.12 × [tex]10^{-9}[/tex] M
QUESTION 4 What is the maximum pressure (in Torr) that will afford a N2 molecule a mean-free-path of at least 1.00 m at 25 oC
Answer:
Maximum pressure P = 4.9 × 10⁻⁵ Pa
Explanation:
From the information given, the mean free path can be expressed with the formula:
[tex]\lambda = \dfrac{RT}{\sqrt{2} \pi \times d^2 \times N_A \times P}[/tex]
Making Pressure P the subject of the formula because we intend to find the maximum pressure, we have:
[tex]P= \dfrac{RT}{\sqrt{2} \pi \times d^2 \times N_A \times \lambda }[/tex]
At standard conditions
R = gas constant = 8.314 J/mol.K
T = temperature at 25°C = (273 + 25) = 298 K
π = pi = 3.14
d = (364× 10⁻¹²m)²
[tex]N_A[/tex] = avogadro's number = 6.023 × 10²³
λ = mean free path = 1.0 m
[tex]P= \dfrac{RT}{\sqrt{2} \pi \times d^2 \times N_A \times \lambda }[/tex]
[tex]P= \dfrac{8.314 \ J/mol.K \times 298 \ K}{\sqrt{2}\times (3.14) \times (364 \times 10^{-12} \ m) ^2 \times 6.023 \times 10^{23}/mol \times 1.0 \ m }[/tex]
P = 0.007 kg/m.s²
P = 0.007 Pa
[tex]P = 0.007 Pa \times \dfrac{0.007 \ torr}{1 \ Pa}[/tex]
P = 4.9 × 10⁻⁵ Pa