The sum of the squares of two sides of a right angle is equal to the square of the hypotenuse
Which one of the following compounds will NOT be soluble in water?
A) LiNO3
B) PbS
C) NaOH
D) MgCl2
E) K2SO4
The forensic technician at a crime scene has just prepared a luminol stock solution by adding 17.0 \({\rm g}\) of luminol into a total volume of 75.0 \(\rm mL\) of \(\rm H_2O\). What is the molarity of the stock solution of luminol
Answer:
1.28 M
Explanation:
Step 1: Given data
Mass of luminol (solute): 17.0 g
Volume of water: 75.0 mL (this is also the volume of solution)
Step 2: Calculate the moles corresponding to 17.0 g of luminol
The molar mass of luminol is 177.16 g/mol.
17.0 g × 1 mol/177.16 g = 0.0960 mol
Step 3: Calculate the molarity of the solution
We will use the definition of molarity
M = moles of solute / liters of solution
M = 0.0960 mol / 0.0750 L = 1.28 M
Consider a hypothetical metal that has a density of 10.6 g/cm3, an atomic weight of 176.8 g/mol, and an atomic radius of 0.130 nm. Compute the atomic packing factor if the unit cell has tetragonal symmetry, values for the a and c lattice parameters are 0.570 and 0.341, respectively.
Answer:
0.3323
Explanation:
GIven that:
Density of the metal = 10.6 g/cm^3
atomic weight = 176.8 g/mol
atmic radius = 0.130 nm
values of a and c = 0.570 nm and 0.341 nm respectively
For us to determine the atomic packing factor, we need to first determine the volume of all spheres (Vs) and the volume of unit cell (Vc).
However, the number of atoms in the unit cell (n) can be computed as:
[tex]n = \dfrac{\rho * V_c *N_A}{A} \\ \\ n = \dfrac{(10.6) * (5.7)^2 (3.41)*(10^{-24}) *(6.022*10^{23})}{176.8}[/tex]
n = 4.0
Thus, the number of atoms in the unit cell is 4
∴
The atomic paking factor (APF) is calculated by using the formula:
[tex]\dfrac{Vs}{Vc} = \dfrac{4 * \dfrac{4}{3}\pi *R^3 }{a^2 *c} \\ \\ \\ \dfrac{Vs}{Vc} = \dfrac{4 * \dfrac{4}{3}\pi *(1.30*10^{-8})^3 }{(5.70*10^{-8})^2 *(3.41*10^{-8})}[/tex]
= 0.3323
potassium and chlorine react to form potassium chloride. a.it is a redox reaction,explain why. b.see if u can write a balanced equation for it.
Answer:
K+ClKCl
Explanation:
because the reaction is between metal Potassium and Non-metal Chlorine
Answer:
Explanation:
a) It is a redox reaction because KCl is an ionic compounds with K having a + charge and Cl having a - charge. Originally, both have an oxidation state of 0 and not K has 1+ and Cl has 1-. Therefore, one species was oxidized and one was reduced which is indicative of a redox reactions.
b)
2K + Cl2 => 2KCl
Which option is an isotope with 6 protons and 8 neutrons? (1 point)
O oxygen-6
o carbon-14
o oxygen-14
o carbon-8
Answer:
Carbon-14
Explanation:
It is because it have 6 protons and 8 neutrons which are added together to form an atomic mass of 14.
The mass number of an isotope is the sum of the number of protons and number of neutrons hence the correct answer is carbon-14.
Isotopes are atoms of the same element that has the same number of protons but different number of neutrons.
The atomic number is the same as the number of protons in the atom. Since there are six protons in the atom, the element must be carbon.
There are eight neutrons meaning that the mass number is 8 + 6 = 14
Therefore, the isotope is carbon-14.
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When naming organic compounds, there are strict rules regarding punctuation.
1. A comma is used to separate two numbers.
2. A hyphen is used to separate a number from a letter.
Rewrite the name of this compound using hyphens and commas as appropriate.
The question is incomplete, the complete question is shown in the image attached to this answer
Answer:
2,3,3-trimethylhexane
Explanation:
IUPAC nomenclature provides a universally acceptable method of naming organic compounds from its structure.
According to this system of nomenclature;
A comma is used to separate two numbers.
A hyphen is used to separate a number from a letter.
Applying these rules, the name of the compound shown in the question should be written as 2,3,3-trimethylhexane.
A person uses 400.8 kcal of energy to run a race. Convert the energy used for the race to the following energy units:
(provide an answer in 4 significant figures)
Calories
calories
Food Calories
Joules
Kilojoules
Hint: 1kcal=4.184kJ
Calories, we know that fat burn is calories.
Alex drips hydrochloric acid onto a 5.9 g piece of magnesium in a single displacement reaction. How many molecules of HCl are required? 2HCl(aq) + Mg(s) → MgCl2(aq) + H2(g)
how do you do this?
2.96 × 10²³ molecules is required if Alex drips hydrochloric acid onto a 5.9 g piece of magnesium in a single displacement reaction
According to this question, hydrochloric acid (HCl) reacts with magnesium metal (Mg) to produce magnesium chloride and hydrogen has as follows:
2HCl(aq) + Mg(s) → MgCl2(aq) + H2(g)
Based on the balanced chemical equation above; 2 moles of HCl reacts with 1 mole of Mg. Next, we convert 5.9g of Mg to moles by using the formula; mole = mass/molar massWhere; Mg = 24g/mol
mole = 5.9/24
mole = 0.246mol of Mg
If 2 moles of HCl reacts with 1 mole of Mg. 0.246 mol of Mg will react with (0.246 × 2) = 0.492mol of HClTo convert mole to number of molecules, we multiply number of moles by 6.02 × 10²³ (Avogadro's no.)
Hence, number of molecules of HCl required is 0.492mol × 6.02 × 10²³
= 2.96 × 10²³ molecules of HClHCl
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10. At 573K, NO2(g) decomposes forming NO and O2. The decomposition reaction is second order in NO2 with a rate constant of 1.1 M-1s-1. If the initial concentration of NO2 is 0.056 M, how long will it take for 75% of the NO2 to decompose
Answer:
48.67 seconds
Explanation:
From;
1/[A] = kt + 1/[A]o
[A] = concentration at time t
t= time taken
k= rate constant
[A]o = initial concentration
Since [A] =[A]o - 0.75[A]o
[A] = 0.056 M - 0.042 M
[A] = 0.014 M
1/0.014 = (1.1t) + 1/0.056
71.4 - 17.86 = 1.1t
53.54 = 1.1t
t= 53.54/1.1
t= 48.67 seconds
Hence,it takes 48.67 seconds to decompose.
Determine the relative formula mass of dihydrogen monoxide using the periodic table below.
A. 18 g/mol
B. 17 g/mol
C. 16 g/mol
D. 2 g/mol
The relative atomic mass of dihydrogen monoxide is 18g/mol
Dihydrogen monoxide is a molecule containing two atoms of hydrogen and one atom of oxygen i.e. H2O. It is widely regarded as WATERTo calculate the relative atomic mass of dihydrogen monoxide (H2O), we make use of the atomic mass of each element.According to the periodic table:
Where; H = 1g/mol and O = 16g/mol
H2O = 1(2) + 16
= 2 + 16
= 18g/mol
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How to distinguish between ethanol and 2 -methyl-2-propanol
Answer:
There are many reagents.
1. Use acidified potassium permanganate solution
2. Use acidified potassium dichromate solution
3. Fehling solution.
4. Silver/ oxygen at 500°C
5. Copper/ oxygen at 300°C
6. Lucas reagent ( anhydrous zinc and conc. hydrochloric acid)
Explanation:
Observations:
[with acidified potassium permanganate solution]
» Ethanol : The purple solution turns colourless.
» 2-methyl-2-propanol : no observable change.
[with acidified potassium dichromate solution]
» Ethanol : orange solution turns green
» 2-methyl-2-propanol : no observable change.
[Fehling solution]
» Ethanol : a white precipitate is formed
» 2-methyl-2-propanol : no observable change
Which of the following pairs lists phase changes that both give off energy?
a) Freezing and condensation
b) Deposition and vaporization
c) Vaporization and melting
d) Condensation and sublimation
Answer:
a) Freezing and condensation
Explanation:
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A 25.00 gram sample of an unknown metal initially at 99.0 degrees Celcius is added to 50.00 grams of water initially at 10.55 degrees Celcius. The final temperature of the system is 20.15 degrees Celcius. Calculate the specific heat of the metal. (The specific heat of water is 4.184 J/g*C).
Answer:
1.0188 J/g*C
Explanation:
Using the formula; Q = m × c × ∆T
Q(water) = -Q(metal)
m × c × ∆T (water) = -{m × c × ∆T (metal)}
According to this question,
mass of metal = 25g
initial temp of metal = 99°C
mass of water = 50g
initial temp of water = 10.55°C
final temperature of the system = 20.15°C
c of water = 4.184 J/g*C
50 × 4.184 × (20.15 - 10.55) = 25 × c × (20.15 - 99)
209.2 × 9.6 = 25c × -78.85
2008.32 = -1971.25c
c = 2008.32 ÷ 1971.25
c of metal = 1.0188 J/g*C
Why is bromine more electronegative than iodine?
Answer
Accordingly the order of electronegativity of the given elements would be: Fluorine > Chlorine > Bromine > Iodine. ( Fluorine has the highest electronegativity.)
Which of the following is an example of an optional deduction ? " a ) Medicare Ob ) Social Security c ) Retirement plan d ) State tax
Medicare
United states program for people who are older than 60
Draw the structure of the organic product(s) of the Grignard reaction between methyl benzoate and excess phenylmagnesium bromide, followed by aqueous workup. You do not have to consider stereochemistry. If a compound is formed more than once, add another sketcher and draw it again. Alternatively, you may use the square brackets tool to add stoichiometries greater than one. Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. Separate multiple products using the sign from the drop-down menu.
Answer:
See explanation and image attached
Explanation:
The product of the Grignard reaction between methyl benzoate and excess phenylmagnesium bromide is triphenyl methanol.
The reaction proceeds by nucleophillic reaction as the carbonyl moiety is attacked. A tetrahedral intermediate is formed. Loss of the -OMe group is accompanied by the attack of the first molecule of PhMgBr.
Attack by a second PhMgBr molecule yields trimethyl phenoxide. Protonation of this specie yields the final product which is obtained by aqueous workup.
The surface of silver metal, Ag(s), became tarnished when it was exposed to oxygen, producing Ag2O. In Ag2O, the oxidation state of silver is 1. According to this information, silver metal was _____. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices reduced
Answer: The silver metal was OXIDIZED.
Explanation:
OXIDATION is defined as loss of electrons and increase in oxidation number of an atom.
Oxidation number is the charge on an ion in an ionic compound or the charge that an atom in a covalent compound would have it it were ionic. There are basic rules governing oxidation number, they include:
--> the oxidation number of elements in their free states is ZERO. Example O2, Cl2,Na, Al, Ag.
-->The oxidation number for an ion is the same as the size and sign of the charge on the ion. For example the oxidation number of Zn2+ is +2.
--> the sum of all the oxidation numbers of the elements in a compound is zero.
--> oxidation numbers are always written with either a positive or a negative sign.
On the other hand, reduction is the opposite of oxidation. As oxidation is taking place, reduction is also taking place. Reduction involves:
--> Gain of electron and
--> decrease in oxidation number
From the question, the silver metal had ZERO as it's oxidation number because it's in free state. After being exposed to oxygen to form silver oxide, the oxidation number became +1.
Since there is an increase in the oxidation number, the silver metal was OXIDIZED
describe cold blooded animal.also some five example.
Answer:
Cold blooded animals are animals which stay in water
Explanation:
Examples are;snakes,tortoises,turtles,crocodiles,alligators
why Ethyl amine is more basic than aniline?
Answer:
Because a Lone pair of electrons on nitrogen is involved in delocalization.
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Explanation:
In ethylamine ethyl is electron donating group. So more electrons are available aroudn nitrogen for donation. But in aniline phenyl group is electron attracting group.
Three peptides were obtained from a trypsin digestion of two different polypeptides. Indicate the possible sequences from the given data.
a. Val-Gly-Arg
b. Ala-Val-Lys
c. Ala-Gly-Phe
Answer:
A) Val-Gly-Arg-Ala-Val-Lys-Ala-Gly-Phe
B) Ala-Val-Lys-Val-Gly-Arg-Ala-Gly-Phe
Explanation:
The possible sequences that could be obtained from the available dat provided are :
A) Val-Gly-Arg-Ala-Val-Lys-Ala-Gly-Phe
B) Ala-Val-Lys-Val-Gly-Arg-Ala-Gly-Phe
Trypsin is generally a catalyst for the breakdown of proteins into smaller peptides ( during the hydrolysis of peptide bonds )
Butanal, an aldehyde, can be made from 1-bromobutane, but it requires two reactions in sequence. What are the two reagents that can be used to make butanal from 1-bromobutane if reagent A is first reacted with 1-bromobutane and then the product of that reaction, is reacted with reagent B.
Answer:
See explanation and image attached
Explanation:
My aim is to convert 1-bromobutane to butanal. The first step is to react the 1-bromobutane substrate with water. This reaction occurs by SN2 mechanism to yield 1-butanol. Hence reagent A is water.
1-butanol is now reacted with an oxidizing agent such as acidified K2Cr2O7 (reagent B) to yield butanal. Note that primary alkanols are oxidized to alkanals.
These sequence of reactions are shown in the image attached.
Problem 7 (Diffusion due to viscosity) If the viscosity of a solution is quadrupled, the rms-average distance of a collection of diffusing molecules from their starting point would be _________ over the same amount of time.
Answer:
1/2 the distance
Explanation:
If the viscosity of a solution is quadrupled then the distance of collection of diffusing molecules would be half over the same amount of time. The viscosity of the molecules is dependent on density of the liquid. It is independent to the volume of the liquid.
Give the change in condition to go from a gas to a solid. Group of answer choices cool or increase pressure cool or reduce pressure increase heat or reduce pressure increase heat or increase pressure none of the above
Answer:
cool or increase pressure
Explanation:
For a gas to form solid. There must be reduced heat and pressure. The deposition of gas into solid occurs through the removal of thermal energy. The air looses thermal energy and changes into solid.Which one of these statements is/are true: I. All redox reactions with positive emfs are spontaneous. II. If a redox reaction is spontaneous, it must be fast. III. A spontaneous redox reaction will have a cathode reaction that has a more negative reduction potential than the anode. III only. I and III are true. I only. II only. All of I, II, and III are true.
Answer:
yea all the answers are true
Redox reaction is the transfer of the electron from one species to another. All of the three statements are true about the redox reaction.
What is a redox reaction?A redox reaction is a type of chemical reaction in which the electrons are gained and lost by a species. The positive EMF of the cell results in spontaneous and will move the reaction in the forward direction.
In a redox reaction, the cathode reaction is comparatively more negative than the reduction potential present at the anode.
Therefore, option E. All I, II, and III are true.
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What does the third quantum number (m) describe?
A. Which energy level the electron is in
B. What type of orbital the electron is in
C. What direction the electron is spinning
D. The specific orbital within a sublevel
The third quantum number (m) describes the specific orbital within a sublevel. The correct answer is option D.
Quantum numbers are a set of four numbers that describe the properties of an electron in an atom. They specify the energy, position, and orientation of an electron in an atom.
The third quantum number (m) is also called the magnetic quantum number. It describes the orientation of the orbital in space. Each orbital within a sublevel has a different orientation in space, and the magnetic quantum number tells us which orbital we are talking about.
The value of m can range from -l to +l, where l is the second quantum number (the angular momentum quantum number). The value of l determines the number of orbitals in a sublevel, and the value of m determines the specific orbital within that sublevel.
In conclusion, the third quantum number (m) describes the specific orbital within a sublevel. It tells us how the orbital is oriented in space, and it can have values ranging from[tex]\rm -l \ to +l[/tex], where l is the second quantum number.
Option D is the correct answer.
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What is the relationship between temperature and kinetic energy?
Answer:
"[Temperature is a measurement of the average kinetic energy of the molecules in an object or a system. Kinetic energy is the energy that an object has because of its motion. The molecules in a substance have a range of kinetic energies because they don't all move at the same speed.]"
Answer:
Temperature is directly proportional to the average translational kinetic energy of molecules in an ideal gas
Explanation:
A 0.204 g sample of a CO3 2- antacid is dissolved with 25.0ml of 0.0981 M HCL. The hydrochloric acid that is not neutralized by the antacid is titrated to a bromophenol blue endpoint with 5.83 ml of 0.104 M NaOH. Assuming the active ingredient in the antsacid sample is CaCO3, calculate the mass of CaCO3 in the sample.
Answer:
0.0922 g
Explanation:
Number of moles of acid present = 25/1000 × 0.0981
= 0.00245 moles
Number of moles of base = 5.83/1000 × 0.104
= 0.000606 moles
Since the reaction of HCl and NaOH is 1:1
Number of moles of HCl that reacted with antacid = 0.00245 moles - 0.000606 moles
= 0.001844 moles
From the reaction;
CaCO3 + 2HCl ----> CaCl2 + H2O + CO2
1 mole of CaCO3 reacts with 2 moles of HCl
x moles of CaCO3 reacts with 0.001844 moles ofHCl
x = 1 × 0.001844/2
= 0.000922 moles
Mass of CaCO3 = 0.000922 moles × 100 g/mol
= 0.0922 g
How are all compounds similar?
A. They are all made up of ions that are held together by attractions.
B. They are all made up of the same few elements.
C. They are all made up of atoms of two or more different elements.
D. They are all made up of atoms that share electrons.
Answer:
the answer is C
Explanation:
a molecule can be made up of two atoms of the same kind, as when two oxygen atoms bind together to make an oxygen molecule
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The standard redox potentials of isolated components of an electron transport chain in a cyanobacterium are found to be as follows:
Complex A: standard redox potential: -100 mV
Complex B: standard redox potential: -780 mV
Complex C: standard redox potential: +510 mV
Complex D: standard redox potential: +310 mV
Plastocyanin: standard redox potential: +360 mV
Which complex will likely have a binding site with high affinity for reduced plastocyanin?
A. Complex A.
B. Complex B.
C. Complex C.
D. Complex D.
Answer:
B. Complex B.
Explanation:
Complex B will have binding site with high affinity for reduced plastocyanin due to greater redox potential. The high number of redox potential will will transport electron chain in cyanobacteria.
Redox potential is the measure of the electron gain or loss to the electrode. For reduced plastocyanin complex B will have the highest affinity.
What is electron affinity?Electron affinity is the energy released when the atom gets attached to the atom or other molecule. The high number of redox potential increases the electron transport in the cell.
The greater the redox potential more will be its tendency to show electron affinity. To bond with reduced species, the oxidized species must have greater redox potential.
Therefore, option B. complex b will have the highest affinity.
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A nitrogen ion has a mass of 14 and a charge of +2. Which subatomic particles does it contain? (1 point)
O 2 protons, 6 neutrons, and 6 electrons
O 7 protons, 7 neutrons, and 5 electrons
O 4 protons, 4 neutrons, and 6 electrons
o 7 protons, 7 neutrons, and 9 electrons
Answer:
7 protons, 7 neutrons, and 5 electrons
Explanation:
the formula for atomic weight=no.of protons + no. of electrons this shortens the options into b or d and second part says that the ion has charge +2 which means it has lost two electrons. so no. of electrons=no.of electrons in nitrogen atom - 2=5.
Nitrogen ion with a charge of +2 has 7 protons, 7 neutrons, and 5 electrons
Explanation:
To obtain the right answer to the question, we must determine the number of proton, neutron and electron of nitrogen ion. This can be obtained as illustrated follow.
Step 1:Data obtained from the question.
Mass number = 14
Charge = +2
Step 2:Determination of the number of proton.
The atomic number of an element is simply the number of protons in the atom of the element.
Atomic number of nitrogen = 7
Thus, the proton number of nitrogen is 7.
NOTE: The atomic number of an element does not change be it atom or ion, it remains the same.
Therefore the proton number of nitrogen ion is 7
Step 3:Determination of the number of neutron
Mass number = 14
Proton number = 7
Neutron number =?Mass number = Proton + Neutron
14 = 7 + Neutron
Collect like terms
14 – 7 = Neutron
Neutron = 7Step 4Determination of the number of electrons.
Charge = +2
Proton number = 7
Electron number =?Charge = Proton – Electron
+2 = 7 – Electron
Collect like terms
2 – 7 = – Electron
–5 = – Electron
Multiply through by –1
Electron = 5SUMMARY:Nitrogen ion with a charge of +2 has:
1. 7 protons
2. 7 neutrons
3. 5 electrons.
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