Answer:
[NaOH} = 0.4 M
Explanation:
In a reaction of neutralization, we determine the equivalence point of the titration. In this case, we have a strong base and a strong acid.
(H₂SO₄, is considered strong, but the first deprotonation is weak)
2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
As we have 2 protons in the acid, we need 2 OH⁻ from the base to form 2 molecules of water.
In the equivalence point we know mmoles of base = mmoles of acid
Let's finish the excersise with the formula
25 mL . M NaOH = 28.2 mL . 0.355M
M NaOH = (28.2 mL . 0.355M) / 25 mL → 0.400
The standard enthalpy of vaporization of methanol is 35.2 kJ/mol at its normal boiling point, 64.6°C. What is the standard change in entropy for the vaporization of methanol at its normal boiling point?
A) 0.104 J/(mol middot K)
B) 104 J/(mol middot K)
C) 545 J/(mol middot K)
D) -35.2 J(mol middot K)
E) 0.545 J(mol middot K)
Answer:
B) 104 J/mol.K
Explanation:
Step 1: Given data
Standard enthalpy of vaporization (ΔH°vap): 35.2 kJ/molNormal boiling point (Tb): 64.6 °CStep 2: Convert "Tb" to Kelvin
We will use the following expression.
K = °C + 273.15
K = 64.6°C + 273.15
K = 337.8 K
Step 3: Calculate the standard change in entropy for the vaporization of methanol (ΔS°vap)
The vaporization is the phase transition from the liquid phase to vapor. We can calculate the standard change in entropy for the vaporization using the following expression.
ΔS°vap = ΔH°vap / Tb
ΔS°vap = (35.2 × 10³ J/mol) / 337.8 K
ΔS°vap = 104 J/mol.K
The standard change in entropy for the vaporization of methanol at its normal boiling point is 104 J/mol.K.
How do we calculate entropy of vaporization?Standard change in entropy for the vaporization will be calculated by using the below equation as:
ΔS°vap = ΔH°vap / Tb, where
ΔH°vap = standard enthalpy of vaporization of methanol = 35.2 kJ/mol
Tb = Boiling point of methanol = 64.6°C = 64.6°C + 273.15 = 337.8 K
On putting all these values on the above equation, we get
ΔS°vap = (35.2 × 10³ J/mol) / 337.8 K
ΔS°vap = 104 J/mol.K
Hence option (B) is correct.
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What is required to cause change in matter
Answer:
Adding or removing energy from matter causes a physical change as matter moves from one state to another. For example, adding thermal energy (heat) to liquid water causes it to become steam or vapor (a gas). And removing energy from liquid water causes it to become ice (a solid). ... Most liquids contract as they freeze.
Explanation:
have a nice day
How much did one drop of HNO3 cause the pH of water to change?
Answer:
-4
Explanation:
It went from a 7 to a 2 and 7-2 is 4, so it changed by 4 and it went down by 4.
One drop of HNO3 will cause the pH of water to change from 7 to 3
What is effect of addition of acid to pH of a water?
The pH of a solution is the negative logarithm of the hydrogen ion concentration of the solution.
pH = - log[H⁺]At equilibrium, the pH of water = 7
The concentration of hydrogen ions is 10⁻⁷ M
If 0.1 mL (about one drop) of 1.0 M HNO3 is added to 100 mL of water: the volume of solution is 100.1 mL and the concentration of solution is calculated thus:
C₁V₁ = C₂V₂
C₂ = C₁V₁/V₂
C₂ = 0.1 * 1/100.1
C₂ = 9.99 * 10⁻⁴ M
Hydrogen ion concentration, [H⁺] = 9.99 * 10⁻⁴ M
pH = - log(9.99 * 10⁻⁴)
pH = 3
Therefore, one drop of HNO3 will cause the pH of water to change from 7 to 3
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What is the shape of the waterline?
__________ energy travels through matter in the form of waves.
Answer:
A wave is a form of energy therefore, it travels through matter in the form of packets of energy. Examples of waves include light, heat and sound waves. Matter from where the waves travel is known as a medium such as if waves travel through ocean then water is the medium.
Explanation: hope this helps
Which isomer of 1-bromo-2-tert-butylcyclohexane reacts faster when refluxed with potassium tert-butoxide?Draw the structure of the expected major product from the faster reacting compound.
Answer:
See explanation and image attached
Explanation:
The reaction of 1-bromo-2-tert-butylcyclohexane with potassium tert-butoxide is an elimination reaction that occurs by E2 mechanism.
The E2 reaction proceeds faster when the hydrogens are in an antiperiplanar position at an angle of 180 degrees.
This is only attainable in the trans isomer of 1-bromo-2-tert-butylcyclohexane. Hence trans 1-bromo-2-tert-butylcyclohexane reacts faster with potassium tert-butoxide
Which of the following statements is true?
Electrons have a positive charge.
Protons and neutrons are found in the nucleus.
Electrons and protons are found in the nucleus.
All shells can hold up to eight electrons.
Answer:
2/ Protons and neutrons are found in the nucleus.
Explanation:
for every 1lb you lose do to sweating you should consume ___ oz of water.
Answer:
For every pound lost, replace it with 16 to 20 ounces of fluid
What is the degree of oxidation of a simple substance
Answer:
The oxidation state of a free element (uncombined element) is zero. For a simple (monoatomic) ion, the oxidation state is equal to the net charge on the ion. For example, Cl– has an oxidation state of -1. When present in most compounds, hydrogen has an oxidation state of +1 and oxygen an oxidation state of -2
Which total mass is the largest?
(A) The mass of 2 electrons
(B) The mass of 2 neutrons
(C) The mass of 1 electron plus the mass of 1 proton
(D) The mass of 1 neutron plus the mass of 1 electron
Answer: B
Explanation: because the subatomic particle with the largest mass is the neutron.
The mineral manganosite, manganese(ll) oxide, crystallizes in the rock salt structure the face-centered structure adopted by NaCl) with a density of 5.365 g/cm'. Find the unit cell edge length of manganosite.
A. 444.5 pm
B. 352.8 pm
C. 280.0 pm
D. 368.2 pm
E. 417.9 pm
Answer:
A. 444.5 pm
Explanation:
We know that:
[tex]Density = \dfrac{mass \ of \ atoms \ in \ unit \ cell}{total \ volume \ of \ unit \ cell}[/tex]
i.e.
[tex]\rho = \dfrac{n*M}{v_c * N_A}[/tex]
[tex]\rho = \dfrac{n*M}{a^3 * N_A}[/tex]
in a face-centered cubic crystal, the number of atoms per unit cell is (n) = 4
The molar mass of manganese (II) oxide [tex][Mn(11)O] = 70.93 \ g/mol[/tex]
Density [tex]\rho[/tex] is given as 5.365 g/cm³
Avogadro constant [tex]N_A[/tex] = 6.023 × 10²³ atoms/mol
∴
[tex]\rho = \dfrac{n*M}{a^3 * N_A}[/tex]
Making th edge length "a" the subject, we get:
[tex]a^3 = \dfrac{n*M}{\rho* N_A}[/tex]
[tex]a^3 = \dfrac{4*70.93 \ g/mol}{5.365 \ g/cm^3 *6.023 * 10^{23} \ atoms/mol }[/tex]
[tex]a^3= 8.78 \times 10^{-23} \ cm^3[/tex]
[tex]a= \sqrt[3]{8.78 \times 10^{-23} \ cm^3}[/tex]
a = 4.445 × 10⁻⁸ cm
a = 444.5 pm
The unit cell edge length of manganosite is equal to: A. 444.5 pm
Given the following data:
Density of NaCl = 5.365 [tex]g/cm^3[/tex]We know that the molar mass of manganese (ll) oxide is equal to 70.93 g/mol.
Avogadro constant = [tex]6.02 \times 10^{23}[/tex]
Since the rock salt is face-centered cubic crystal, the number of atoms per unit cell, n = 4
To find the unit cell edge length of manganosite:
For a crystal structure, density is given by the formula:
[tex]Density = \frac{Mass\; of\;atoms\;in\;a\;unit\;cell}{Total\;volume\;of\;a\;unit\;cell}[/tex]
[tex]\rho = \frac{nM}{N_Aa^3}[/tex]
Where:
n is the number of atoms per unit cell.[tex]N_A[/tex] is Avogadro constant.a is the edge length.M is the mass.Making "a" the subject of formula, we have:
[tex]a=\sqrt[3]{\frac{nM}{\rho N_A} }[/tex]
Substituting the parameters into the formula, we have;
[tex]a=\sqrt[3]{\frac{4 \times 70.93}{5.365 \times 6.02 \times 10^{23} }}\\\\a=\sqrt[3]{\frac{283.72}{3.23 \times 10^{24} }}\\\\a=\sqrt[3]{8.79 \times 10^{-23} }}\\\\a = 4.445 \times 10^{-8}\; meters[/tex]
Unit cell edge length, a = 444.5 pm
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Help me please this is due today
8)
C(diamond) → C(graphite)
delta G° = -2.9 kJ/molrxn
Which of the following best explains why the reaction represented above is not observed to occur at
room temperature?
(A) The rate of the reaction is extremely slow because of the relatively small value of AGº for
the reaction.
(B) The entropy of the system decreases because the carbon atoms in graphite are less ordered
than those in diamond.
(C) The reaction has an extremely large activation energy due to strong three-dimensional
bonding among carbon atoms in diamond.
(D) The reaction does not occur because it is not thermodynamically favorable.
Answer: its b hope this helps.
Explanation:
A catalyst accelerates a reaction because:_____.
a. it increases the number of collisions between molecules.
b. it increases the number of molecules with energy equal to or greater than the activation energy.
c. it supplies energy to reactant molecules.
d. it lowers the activation energy for the reaction.
e. it increases the temperature of the molecules in the reaction.
Answer:
D. Lowering activation energy for the reaction
Explanation:
Catalysts increase the rate of a reaction without being used up. They do this by lowering the activation energy needed. With a catalyst, more collisions result in a reaction, so the rate of reaction increases.
Hope this helped :)
A compound is an example of pure substance
True
False
The density of aluminum is 2.7 g/cm3 and that of Al2O3 is about 4 g/cm3. Calculate the PB ratio for Aluminum. (Hint: The Pilling-Bedworth Ratio (PBR) gives the volume of oxide formed to the volume of metal atoms.)
a) 1.28
b) 0.28
c) 0.75
Answer:
1.28
Explanation:
Al = aluminium
Density of Al = 2.7g/cm³
Density of Al2O3 = 4g/cm³
Molecular weight of Aluminum = 27g/mol
Molecular weight of Al2O3= 101.96 g/mol
Pilling bedworth ratio = Rob
= M(Al2O3) * density of Al / n* molecular weight of Al * density of Al2O3
= 101.96g/mol x 2.7g/cm³/2x 27g/mol x 4g/cm³
= 275.292/216
= 1.28
From the calculation above 1.38nis the PB ratio for aluminum
What's the electron configuration of an N-3 ion?
Question 17 options:
A)
[Ne]
B)
[Ar]
C)
[H]
D)
[He]
Answer:
A. since Nitrogen has 7 electrons and when it gains 3 electrons it will have 10 electrons. using short hand rule it is [Ne]
Why are constellations in predictable in the night sky but why are planets so hard to find?
Two isotopes of hypothetical element X exist with abundances of 30.00% 100X and 70.00% 101X. What is the approximate atomic mass of X (in atomic units, amu)?
(A) 100.3
(B) 100.5
(C) 100.7
(D) 101.0
Answer:
C. 100.7 amu
Explanation:
Isotopes of an element are atoms of an element with the same atomic number but different atomic masses. Each atomic mass of an isotope is known as an isotopic mass. An element that exhibits isotope, that is, that have two or more isotopes has a relative atomic mass that is not a whole number.
Relative atomic mass of X is the sum of the products of the relative abundances of each isotope and its isotopic mass.
For Isotope ¹⁰⁰X: 30% × 100 = 30 amu
For Isotope ¹⁰¹X: 70% × 101 = 70.7 amu
Relative atomic mass of X = (30 + 70.7) amu = 100.7 amu
Therefore, the approximate atomic mass of X is 100.7 amu
Taking into account the definition of mass number, isotopes and atomic mass of an element, the average mass of hypothetical element X is 100.7.
First of all, all atoms are made up of subatomic particles: protons and neutrons, which are part of their nucleus, and electrons, which revolve around them. Protons are positively charged, neutrons are neutrally charged, and electrons are negatively charged (electrons).
On the other hand, the mass number tells us the total number of particles in the nucleus. That is, the mass number is the sum of the number of protons and the number of neutrons in the atomic nucleus.
The same chemical element can be made up of different atoms, that is, their atomic numbers are the same, but the number of neutrons is different. These atoms are called isotopes of the element.
Finally, the atomic mass of an element is the weighted average mass of its natural isotopes.
In other words, the atomic masses of chemical elements are usually calculated as the weighted average of the masses of the different isotopes of each element, taking into account the relative abundance of each of them.
In this case, two isotopes of hypothetical element X exist with abundances of 30.00% 100-X (the atomic mass is 100) and 70.00% 101-X (the atomic mass is 101). Then, the average mass of X can be calculated as:
100×0.30 + 101×0.70= 100.7
Finally, the average mass of hypothetical element X is 100.7.
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Study the diagram of a cell. Which structures are found in both plant and animal cells? W and X W and Z X and Y O Y and Z XN Y -W
Answer:
A I did the exam and I saw A sorry if it is wrong dont have the best of memory
Argon (Ar) is an element in group 18. Argon is _____.
a gas highly reactive
a metalloid
a good conductor of heat
Answer:
c
Explanation:c
it is a good conducter
How many moles of H2O are produced when 3.25 moles of O2 react in the above equation?
a
12.92 moles of H2O
b
3.79 moles of H2O
c
0.06 moles of H2O
d
2.79 moles of H2O
Answer:
D.
Explanation:
using stoichiometric factors to solve this one.
The moles of the reactant and the product produced in the reaction is given by the stoichiometric law. The moles of water produced in the reaction is 2.79 mol.
What is stoichiometric law?The stoichiometric law states the moles of the reactant and the product in the reaction are equivalent to the stoichiometric coefficient.
For the equation given, stoichiometric law states that:
[tex]\rm 7\;mol\;O_2=6\;mol\;H_2O[/tex]
The moles of water produced from the 3.25 moles of oxygen are:
[tex]\rm 7\;mol\;O_2=6\;mol\;H_2O\\\\3.25\;mol\;O_2=\dfrac{6}{7} \;\times\;3.25\;mol\;H_2O\\\\3.25\;mol\;O_2=2.79\;mol\;H_2O[/tex]
The moles of water produced in the reaction are 2.79 mol. Thus, option D is correct.
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Which sentence best describes a bond formed between two unlike atoms?
O A. The bond could form only between two atoms of very different
electronegativities.
O B. The electrons involved in the bond are shared equally between the
atoms.
O C. The bond could have been formed only as the result of ions
attracting each other.
D. The type of bond is determined by the difference in
electronegativity of the atoms.
The type of bond is determined by the difference in electronegativity of the atoms. Hence, option D is correct.
What is a bond?A chemical bond is what holds atoms together in molecules.
The ability of an atom to attract a pair of electrons in a chemical bond is called its electronegativity. The difference in electronegativity between two atoms determines how polar a bond will be.
Hence, option D is correct.
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Most elements are __ at room temperature
Answer:
Most elements are Solids at room temperature
Cl2 +
NaBr
-
NaCl +
Br2
Answer:
hope this helps :)
Explanation:
Cl2 + NaBr = NaCl + Br2
NaCl + Br2 = NaBr + Cl2
its snowing RIGHT NOW yay santa!!!!
Answer:
Yay
Explanation:
could i have a heart and branliest plss
When 240 mg of a certain molecular compound X are dissolved in 35.0 g of dibenzyl ether ((C6H5CH2)2O), the freezing point of the solution is measured to be 1.0 °C. Calculate the molar mass of X If you need any additional information on dibenzyl ether, use only what you find in the ALEKS Data resource. Also, be sure your answer has a unit symbol, and is rounded to the correct number of significant digits.
Answer: MM = 16.55 g/mol
Explanation: Freezing point depression is a phenomena that explains why adding a solute to a solvent decreases the solvent freezing point: when a substance begins to freeze, its molecules slows down and rearrange itself forming a solid. If a solute is added, the molecules from the solvent interfere in the formation of the solid. To guarantee the transformation, the solution has to cooled down even more.
Freezing point and molality concentration is related by
[tex]\Delta T=T_{f}_{(solvent)}-T_{f}_{(solution)}=K_{f}.m[/tex]
where
ΔT is freezing point depression
[tex]T_{f}_{(solvent)}[/tex] and [tex]T_{f}_{(solution)}[/tex] are freezing point of solvent and solution, respectively
[tex]K_{f}[/tex] is freezing point depression constant
m is molality concentration
Dibenzyl ether is the solvent and has the following properties: [tex]K_{f}=[/tex] 6.27 and [tex]T_{f}[/tex] = 3.6°C.
Molality concentration is
[tex]m=\frac{T_{(solvent)}-T_{(solution)}}{K_{f}}[/tex]
[tex]m=\frac{3.6-1}{6.27}[/tex]
m = 0.415
Molality concentration is moles (n) of solute dissolved in a mass, in kilogram, of solvent.
[tex]m=\frac{moles}{mass(kg)}[/tex]
n = m(mass of solvent in kg)
n = 0.415(0.035)
n = 0.0145
Molar mass (M) is the weight of one sample mole and can be calculated as
[tex]n=\frac{m}{M}[/tex]
M = [tex]\frac{m}{n}[/tex]
m in grams
Molar mass of compound X is
[tex]M=\frac{0.24}{0.0145}[/tex]
M = 16.55
Molar mass of molecular compound X is 16.55g/mol
55. Which Element has a larger radius- Rb or I?
Rb has larger radius.
Discard the water from the first step and re-fill the tall drinking water glass with the chilled water. Then slowly pour a small amount of the hot, green freshwater into the water in the drinking glass. Describe and explain you observations.
Answer:
The hot water remains at the top of chilled water.
Explanation:
The hot water remains at the top of chilled water because hot water has less denser as compared to chilled water. Due to higher density of chilled water, it remains at the bottom due to its greater mass while on the other hand, the hot freshwater goes upward and spreads at the top of the chilled water due to lower mass so when the hot water is added to the chilled water, hot water remains at the top.
A 25.00 mL sample of vinegar was titrated with 39.27 mL of 0.4293 M NaOH. Calculate the concentration of acetic acid in the vinegar sample.
HC2H302 + NaOH NaC2H302 + H2O
Answer:
0.6743 M
Explanation:
HC₂H₃O₂ + NaOH → NaC₂H₃O₂ + H₂O
First we calculate how many NaOH moles reacted, using the definition of molarity:
Molarity = moles / volumemoles = Molarity * volume0.4293 M * 39.27 mL = 16.86 mmol NaOHOne NaOH moles reacts with one acetic acid mole, so the vinegar sample contains 16.86 mmoles of acetic acid as well.
Finally we calculate the concentration (molarity) of acetic acid:
16.86 mmol HC₂H₃O₂ / 25.00 mL = 0.6743 M