Answer:
True
Explanation:
The valence orbitals of boron are 2s2 2p1. We have to recall that all the valence orbitals whether full or empty are involved in the formation of molecular orbitals.
The number of molecular orbitals formed is equal to the number of atomic orbitals that are combined.
Since there are two valence orbitals and there is only one p orbital among the valence orbitals, it is true that only one p orbital is needed to form molecular orbitals in boron.
Excluding any secondary chemical reactions,
which would be more effective as an antifreeze; a
solution containing
Select one:
25m CH3OH
the combination of 25m CH3OH and 25m
KCI.
O 25m KCI.
O
none of these
Answer:
Excluding any secondary chemical reactions,
which would be more effective as an antifreeze; a
solution containing
Select one:
25m CH3OH
the combination of 25m CH3OH and 25m
KCI.
25m KCI.
Explanation:
Antifreeze is the one that reduces the freezing point of a solvent further and will not allow the solvent to freeze.
Among the given options, the correct option is:
25 m CH3OH and 25m KCl.
Since, KOH is a strong electrolyte and dissociates into two ions.
So, the freezing point of solvent decreases further.
Suppose you perform a titration of an unknown weak acid solution. You start with 4.00 mL of the weak acid and find that it takes 14.2 mL of 0.0500 M NaOH to reach the equivalence point. What is the concentration of the unknown weak acid solution
Answer:
0.1775 M
Explanation:
The reaction that takes place is:
HA + NaOH → NaA + H₂OWhere HA is the unknown weak acid.
At the equivalence point all HA moles are converted by NaOH. First we calculate how many NaOH moles reacted, using the given concentration and volume:
0.0500 M NaOH * 14.2 mL = 0.71 mmol NaOHThat means that in 4.00 mL of the weak acid solution, there were 0.71 weak acid mmoles. With that in mind we can now calculate the concentration:
0.71 mmol HA / 4.00 mL = 0.1775 MThe first law of thermodynamics defines chemical energy. defines entropy. is a statement of conservation of energy. provides a criterion for the spontaneity of a reaction.
Answer: The first law of thermodynamics is a statement of conservation of energy.
Explanation:
According to the first law of thermodynamics, heat provided to a system is actually the sum of internal energy and work done by the system or on the system.
Mathematically, [tex]\Delta Q = \Delta U + \Delta W[/tex]
The first law of thermodynamics also means that energy can neither be created nor it can be destroyed. Hence, energy is conserved.
Thus, we can conclude that the first law of thermodynamics is a statement of conservation of energy.
Para formar bronce, se mezclan 150g de cobre a 1100°C y 35g de estaño a 560°C. Determine la temperatura final del sistema.
Dato: Ce Cu: 0,093 cal/gºC; Ce Sn: 0,060 cal/gºC
Answer:
[tex]T_F=1029\ºC[/tex]
Explanation:
¡Hola!
En este caso, dada la información, es posible determinar que la temperatura del sistema estará entre 560 °C y 1100 °C, por lo tanto, se hará necesario establecer la suma de la energía del cobre y del estaño como cero:
[tex]Q_{Cu}+Q_{Sn}=0[/tex]
Así, podremos escribir esta ecuación en términos de masas, calores específicos y temperaturas como sigue:
[tex]m_{Cu}C_{Cu}(T_F-T_{Cu})+m_{Sn}C_{Sn}(T_F-T_{Sn})=0[/tex]
Con el fin de resolver para la temperature final:
[tex]T_F=\frac{m_{Cu}C_{Cu}T_{Cu}+m_{Sn}C_{Sn}T_{Sn}}{m_{Cu}C_{Cu}+m_{Sn}C_{Sn}}[/tex]
Así, reemplazamos las variables conocidas como se muestra a continuación:
[tex]T_F=\frac{150g*0.093cal/g\ºC*1100\°C+35g*0.060cal/g\ºC*560\°C}{150g*0.093cal/g\ºC+35g*0.060cal/g\ºC}\\\\T_F=1029\ºC[/tex]
¡Saludos!
An electron-dot structure is a convenient method of representing
A. The complete electron configuration of the atom.
B. all electrons of the atom.
C. valence electrons of an atom.
D. core electrons of an atom.
Answer:
all electrons of the atom
In an exothermic chemical reaction:____.
A. The mass of the products is greater than the mass of the reactants.
B. The mass of the products is less then the mass of the reactants.
C. Heat is released as the reaction proceeds.
D. Heat is absorbed as the reaction proceeds.
Answer:
C
Explanation:
Think of 'exo' as exit and 'thermic' as relating to thermal energy/ heat. Thus, an exothermic release thermal energy as the reaction proceeds.
In an exothermic reaction, the total energy of the products is lesser than that of the reactants and ΔH (change in energy) is less than zero.
When heat is absorbed as the reaction proceeds, the chemical reaction is an endothermic reaction.
Predict the products of below reaction, and whether the solution at equilibrium will be acidic, basic, or neutral.
N2O5 + 3H2O → __________
Answer: The product of the given reaction is [tex]HNO_{3}[/tex] and the solution at equilibrium will be acidic.
Explanation:
When two or more chemical substances react together then it forms new substances and these new substances are called products.
For example, [tex]3N_{2}O_{5} + 3H_{2}O \rightarrow 6HNO_{3}[/tex]
This shows that nitric acid [tex](HNO_{3})[/tex] is the product formed and it is an acidic substance.
Hence, the solution at equilibrium will be acidic in nature.
Thus, we can conclude that the product of the given reaction is [tex]HNO_{3}[/tex] and the solution at equilibrium will be acidic.
When electrons in a molecule are not found between a pair of atoms but move throughout the molecule, this is called Group of answer choices
Answer:
delocalised electrons
Explanation:
they are called delocalised electrons because that can move freely in the molecule
A buffer is prepared containing 0.75 M NH3 and 0.20 M NH4 . Calculate the pH of the buffer using the Kb for NH3. g
Answer:
pH=8.676
Explanation:
Given:
0.75 M [tex]NH_{3}[/tex]
0.20 M [tex]NH_{4}[/tex]
The objective is to calculate the pH of the buffer using the kb for [tex]NH_3[/tex]
Formula used:
[tex]pOH=pka+log\frac{[salt]}{[base]}\\[/tex]
pH=14-pOH
Solution:
On substituting salt=0.75 and base=0.20 in the formula
[tex]pOH=-log(1.77*10^{-5})+log\frac{0.75}{0.20}\\ =4.75+0.5740\\ =5.324[/tex]
pH=14-pOH
On substituting the pOH value in the above expression,
pH=14-5.324
Therefore,
pH=8.676
The titration of a weak acid with a strong base is a common exercise in chemistry labs. We have looked at all of the individual types of calculations needed to determine the pH at any point of a titration. Consider the titration of 0.100 L of 0.300 M acetic acid with 2.00 M NaOH. What type of calculation will we be performing at the following points of the titration curve
Answer:
1. Weak acid calculation
2. Strong base calculation
3. Strong base calculation
4. Strong base calculation
Explanation:
1. Zero equivalents of base added
2. 0.15 equivalents of base added
3. One equivalent of base added
4. 1.75 equivalents of base added
The equivalents of acetic acid are:
0.100L * (0.300mol/L) = 0.0300 moles of acetic acid = 0.0300Eq.
1. With Zero equivalents of base added you will calculate pH using weak acid calculation because you have only acetic acid (Weak acid) in the solution.
2. When 0.15 equivalents of base are added all the acid reacted and 0.15-0.03 = 0.12 equivalents of Strong base are in excess. With these equivalents and the volume we can find pH using strong base calculation.
3 and 4. As with 0.15 eq. added the 1 eq. and 1.75 eq. produce an excess of strong base and the pH must be calculated by using strong base calculation
The main importance of the titration curve is that it is used show how the pH of the solution changes as a titrant is added to the solution.
What is a titration curve?A titration curve is a plot of pH of the system against the volume of titrant added. The question is incomplete but I will try to explain what a titration curve is.
The main importance of the titration curve is that it is used show how the pH of the solution changes as a titrant is added to the solution.
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Rank each of the following gases in order of increasing urms assuming equivalent amounts and all gases are at the same temperature and pressure where 1 has the lowest urms and 4 has the highest urms.
a. Gas 1 : H2S
b. Gas: He
c. Gas 3: NF3
d. Gas 4: H2O
The Urms refers to the root mean square speed of the gas. The order of increasing Urms for the gases shown in the question; NF3 < H2S < H2O < He.
What is the Urms?The Urms refers to the root mean square speed of the gas. This is ultimately dependent on the relative molecular mass of the gases when they are maintained at the same temperature.
Now, let us look at the order of increasing Urms for the gases shown in the question; NF3 < H2S < H2O < He.
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1. Calculate the number of moles of aluminum, sulfur, and oxygen atoms in 8.00 moles of aluminum sulfate, Al2(SO4)3. 2. Calculate the number of moles of magnesium, chlorine, and oxygen atoms in 6.10 moles of magnesium perchlorate, (Mg(CIO4)2.3. A sample of propane, C3H8, contains 13.8 moles of carbon atoms. How many total moles of atoms does the sample contain?4. A rare gold coin (24 karat, or 100% gold) has a mass of 25.54 g. How many atoms of gold are present in this coin?
Answer:
1) 16.0 moles Al
24.0 moles S
96.0 moles O
2)In 6.10 moles magnesium perchlorate, (Mg(CIO4)2 we have:
6.10 moles Mg
12.2 moles Cl
48.8 moles O
3)4.6 moles of propane (total) contains 13.8 moles of carbon and 36.8 moles of hydrogen atoms
4)The gold coin contains 7.8 *10^22 atoms
Explanation:
Step 1: Data given
Number of moles of aluminum sulfate, Al2(SO4)3 = 8.00 moles
Step 2: Calculate the number of moles
In 1 mol of aluminum sulfate, Al2(SO4)3 we have:
2 moles of Al
3 moles of S
12 moles of O
This means that in 8.00 moles of aluminum sulfate, Al2(SO4)3 we have:
2*8.00 = 16.0 moles Al
3*8.00 = 24.0 moles S
12*8 = 96.0 moles O
2. Calculate the number of moles of magnesium, chlorine, and oxygen atoms in 6.10 moles of magnesium perchlorate, (Mg(CIO4)2
1 mol of magnesium perchlorate, (Mg(CIO4)2 has:
1 Mol of Mg
2 moles of Cl
8 moles of O
In 6.10 moles magnesium perchlorate, (Mg(CIO4)2 we have:
1 * 6.10 moles = 6.10 moles Mg
2*6.10 = 12.2 moles Cl
8*6.10 = 48.8 moles O
3. A sample of propane, C3H8, contains 13.8 moles of carbon atoms. How many total moles of atoms does the sample contain?
In 1 mol of propane, C3H8 we have:
3 moles of C and 8 moles of H
This means if we have 13.8 moles of carbon, we have 13.8/3 = 4.6 moles of propane, C3H8 and 4.6 *8 = 36.8 moles of H
So 4.6 moles of propane contains 13.8 moles of carbon and 36.8 moles of hydrogen atoms
4. A rare gold coin (24 karat, or 100% gold) has a mass of 25.54 g. How many atoms of gold are present in this coin?
Calculate moles of gold:
Moles = mass of gold / molar mass gold
Moles = 25.54 grams / 196.97 g/mol
Moles = 0.1297 moles
Calculate atoms:
Number of atoms = moles * number of Avogadro
0.1297 * 6.022 *10^23 = 7.8 *10^22 atoms
The gold coin contains 7.8 *10^22 atoms
Excited sodium atoms may emit radiation having a wavelength of 589nm. a) What is the wavelength in meters
Answer: When excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].
Explanation:
Given: Wavelength = 589 nm
It is known that,
[tex]1 nm = 10^{-9} m[/tex]
Hence, 589 nm is converted into meters as follows.
[tex]589 nm = 589 nm \times \frac{10^{-9}m}{1 nm}\\= 589 \times 10^{-9} m[/tex]
Thus, we can conclude that when excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].
300.0 mL of a 0.335 M solution of NaI is diluted to 700.0 mL. What is the new concentration of the solution?
Answer: The new concentration of the solution is 0.143 M.
Explanation:
Given: [tex]V_{1}[/tex] = 300.0 mL, [tex]M_{1}[/tex] = 0.335 M
[tex]V_{2}[/tex] = 700.0 mL, [tex]M_{2}[/tex] = ?
Formula used is as follows.
[tex]M_{1}V_{1} = M_{2}V_{2}[/tex]
Substitute values into the above formula as follows.
[tex]M_{1}V_{1} = M_{2}V_{2}\\0.335 M \times 300.0 mL = M_{2} \times 700.0 mL\\M_{2} = 0.143 M[/tex]
Thus, we can conclude that the new concentration of the solution is 0.143 M.
Senario: 2 years ago, a fruit was smuggled into California on a plane from an exotic, far away land. The homeowner saw that the fruit had maggots and tossed it into the backyard, hoping the seed would grow. The larvae hatched out and moved throughout the area. This fictitious insect will destroy fruit and has the possibility of spreading disease killing the trees. The insect consumes plants in the Prunus species of stone fruits? Look up the plant genus Prunus.
Discussion: The insect has spread over a large area of Southern California, discovered at UC Riverside. What steps would you do to control or eradicate the destructive exotic insect?
PLZ HELP THX WITH COLLEGE LEVEL EXPERICENCE
Answer:
The best existing methods of control—artemisinin-based drug treatment and insect control with chemical sprays and treated bednets—can reduce the burden of disease substantially, and can even eliminate the disease in some regions,
hope this will help you more
Identify the statements that correctly describe the saturation temperature of a solution.
A. Any temperature at which the solution is liquid.
B. Any temperature at which all of the compound is solid.
C. The temperature at which solid begins to appear from a cooled solution.
D. The temperature at which the Ksp value can be calculated.
Determine whether methylcyclohexane contains a chiral center. _____ How many different substituents do you count at atom
Answer:
methylcyclohexane does not possess a chiral center
Explanation:
A molecule is said to possess a chiral center if one or more of the atoms in the molecule is bonded to four different atoms or groups.
If we look at methylcyclohexane, none of the carbon atoms in the molecule is bonded to four different atoms or groups hence the molecule contains no chiral centers and will not exhibit optical isomerism.
So, methylcyclohexane has a plane of symmetry thus it is an achiral molecule.
According to the kinetic-molecular theory, gas molecules have
ANSWER:
Part
A. Less energy than molecules of a solid.
B. strong interactions between molecules.
C. little distance between molecule
D. weak interactions between molecules.
Answer:
The choose ( D )
weak interactions between molecules.
Answer:
Explanation:
el a
which selection is an example of an electrolyte
a. potassium iodide in water
b. sucrose in water
c. pentane in octane
d. methanol in water
Answer:
i believe its A, potassium iodide in water
Explanation:
which of the following is not an instance of benefit in from gases ?
1) filling thermometers
2) inflating tyres
3) in LP gas cylinders
4) in pressure cookers
Answer:
1) filling thermometers
Explanation:
thermometers are filled with liquid mercury
You have been sent a sample of aspirin to analyse for impurities. Describe how you could
determine if the sample is pure aspirin or not using your knowledge of chemistry.
Answer:
The aspirin could be determined if pure or not by testing it with FeCI3 (aq)
The sample of aspirin can be tested for it's purity by treating it with compound of ferric chloride.
What is a compound?Compound is defined as a chemical substance made up of identical molecules containing atoms from more than one type of chemical element.
Molecule consisting atoms of only one element is not called compound.It is transformed into new substances during chemical reactions. There are four major types of compounds depending on chemical bonding present in them.They are:
1)Molecular compounds where in atoms are joined by covalent bonds.
2) ionic compounds where atoms are joined by ionic bond.
3)Inter-metallic compounds where atoms are held by metallic bonds
4) co-ordination complexes where atoms are held by co-ordinate bonds.
They have a unique chemical structure held together by chemical bonds Compounds have different properties as those of elements because when a compound is formed the properties of the substance are totally altered.
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HELP ME PLEASE!!!!!!
I WANT IT AS PARAGRAPHHHHH NOT POINT AND ANSWER THIS TWO QUESTIONS AS 1 PARAGRAPH
One of the lab safety rules being violated is that Jodi doesn't have her hair tied up. She should have her hair tied up. Having her long hair not tied up or away from her face is a safety hazard. Jodi is also not wearing glasses, which is essential when working with chemicals. One of the Bunsen Burners aren't being used but it's on, which is a fire hazard.
Answer:
Jodi should wear her hair up to avoid a mishap, such as lighting her hair on fire. Then, instead of using a fire extinguisher on Jodi, Kimberly should use a fire blanket to prevent additional damage. Mac is preoccupied with a second flame and maybe Jodi without her safety goggles?
what is the molar masses for C8H10N2O4
Answer:
198.2 g/mol
Explanation:
C = 12.01 g/mol
H = 1.01 g/mol
N = 14.01 g/mol
O = 16.00 g/mol
(12.01 x 8) + (10 x 1.01) + (14.01 x 2) + (16.00 x 4) = 198.12 g/mol
Which observation provided Albert Einstein the clue that he needed to explain the photoelectric effect?
Answer:
Einstein realized that the energy in electrons was caused by the frequency of light and not the intensity of light. This made him realize that he needed to explain the photoelectric effect.
Explanation:
Einstein realized that the photoelectric effect was a system that should be studied and explained in more depth, when he saw how the energy of electrons behaved in the presence of light. He saw that this energy depends entirely on the frequency of light and not on the intensity of light. From this observation, he realized that the photoelectric effect was essential for the production of an electric energy system, through light energy, such as solar energy.
It is important to note that the photoelectric effect refers to the ejection of electrons on a light surface that comes into contact with a light source.
i.What are organic fertilizers?
ii.State three advantages of organic fertilizers over inorganic fertilizers.
Answer:
Organic fertilizers are those fertilizers that are not artificially produced but are natural and has carbon in them.
Fertilizers in the broad term are used to provide nutrient to the soil and boost growth of crops.
Some of the advantages of organic fertilizers to inorganic fertilizers are:
They do not make crusts on the soil, unlike inorganic fertilizers.
They help add structure to the soil because of the good water movement into the soil
They are easier on the soil because they feed good microbes.
(URGENT!) Which of these graphs best models the waves in the four locations?
(100 points)
i can not understand the question. There seems to be missing info
How many hydrogen atoms are in 3.90 mol of ammonium sulfide?
Answer:
First, the number of ammonium sulfide molecules should be calculated:
N = NA × n,
where NA - the Avogadro number, n - number of moles.
N (ammonium sulfide) = 6.022 × 1023 × 8.5 mol = 51.187 × 1023.
The moelcular formula of ammonium sulfide is (NH4)2S. It means that each molecule contains 8 hydrogen atoms.
As a result, 8.5 mol of (NH4)2S contain:
51.187 × 1023 × 8 = 41 × 1024 hydrogen atoms.
Answer: 41 × 1024 hydrogen atoms
ELECTROLYSIS OF MOLTEN NaCl IS DONE IN A DOWNS CELL OPERATING AT 7.0 VOLTS AND 4.0X10^4A. HOW MUCH Na(s) AND Cl2(g) CAN BE PRODUCED IN 8 HOURS IN SUCH A CELL?
Answer:
Mass of sodium produced = 2.74 × 10⁵ g of Na
Mass of chlorine produce = 4.24 × 10⁵ g of Cl₂
Explanation:
In the electrolysis of molten NaCl as described above, the quantity of charge used is given by the formula, Q = I × t
Where I isnthe current passed in amperes and t is time in seconds.
Q = 4.0 × 10⁴ A × (8 × 60 × 60) s = 1.152 × 10⁹ C
Equation for the discharge of sodium is; Na+ + e- ---> Na (s)
One mole of electrons is required to discharge one mole of Na
One mole of electron = 1 faraday = 96500 C
One mole of Na has a mass of 23 g
96500 C produces 23 g of Na
1.152 × 10⁹ C will produce 23 g × 1.152 × 10⁹ C / 96500 C = 2.74 × 10⁵ g of Na
Equation for the discharge of chlorine gas is; 2 Cl- ---> Cl₂(g) + 2e-
Two mole of electrons are required to discharge one mole of chlorine gas
Two moles of electron = 2 faraday = 2 × 96500 C = 193000
One mole of Cl₂ has a mass of 71 g
193000 C produces 71 g of Cl₂
1.152 × 10⁹ C will produce 71 g × 1.152 × 10⁹ C / 193000 C = 4.24 × 10⁵ g of Cl₂
The amount of Na produced is 274551 g and the amount of Cl₂ produced is 423763.5 g.
Current passed through the cell = [tex]4.0\times10^4 A[/tex]
Time = 8 Hours
We have to calculate the amount of Na and [tex]Cl_2[/tex] produced in 8 hours in the downs cell.
What is a down cell?The Downs process is an electrochemical method for the commercial preparation of metallic sodium, in which molten NaCl is electrolyzed in a special apparatus called the Downs cell.
The total charge passed through the cell is calculated by the given formula as
Charge(Q) = Current(I) × time(t)
Q = [tex]4.0\times10^4 A \times t[/tex]
[tex]t = 8 \times 60\times 60[/tex] sec
t = 28800 sec
Q = [tex]4.0\times10^4 A \times 28800[/tex] sec
Q = [tex]115200\times 10^4 A\ sec[/tex]
We know that, Ampere = Coulombs per sec
Q = [tex]115200\times 10^4\ C[/tex]
1 mol of electrons 96500 C charge
Therefore, the number of mols of electrons carries this [tex]115200\times 10^4\ C[/tex] charge = [tex]\frac{115200\times10^4}{96500}[/tex] = 1.1937 × 10⁴ = 11937 mol electrons
In the Down's cell
Half cell reactions are:
Reduction half-reaction: [tex]2Na^+(aq)+2e^- \to 2Na(s)[/tex]
Oxidation half-reaction: [tex]2Cl^-(aq)\to Cl_2(g) + 2e^-[/tex]
We know that no. of moles = [tex]\frac{given \ mass}{molar \ mass}[/tex]
Molar mass of Na = 23 g/mol
The mass of Na formed = 11937 mol × 23 g/mol = 274551 grams
The molar mass of Cl₂ = 71 g/mol
The mass of Cl₂ = [tex]\frac{11937}{2}\times 71 = 423763.5 \ grams[/tex]
Hence, the amount of Na produced is 274551 g and the amount of Cl₂ produced is 423763.5 g.
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A chemistry grad student measures the performance of the new pump in his lab. The result is:Convert to
Answer:
The correct answer is - 0.0188 mJ*s^-1.
Explanation:
In order to convert the kPA value to PA value--
and then convert PA unit to 1 kgm^-1s^-2
And in finally convert mm to m
The value that come should be convert from kgm^2s^-2 to and then convert J to mJ or kJ by dividing 100 or 100 subsequently.
As no question given this method can be followed for the answer.
Where do reactions in a solid
generally take place?
A. All throughout the solid
B. At the center of the solid.
C. Only on opposite sides of the solid
due to repelling forces.
D. On the surface of the solid.
Answer:
A
Explanation:
because solid stick together like magnetic and can feel every vibration
Answer:D
Explanation: on the surface of a solid