Answer
The Ozone Layer
Explanation
Higher up, in the stratosphere, the ozone layer absorbs solar ultra-violet radiation and affects how much of the Sun's heat is radiated back into space. The ozone layer shields us from the harmful effects of excessive UV radiation, which can lead to sunburn, skin cancer and eye damage.
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in part 2 of the experiment, you will be analyzing a sample of household bleach. a 0.0854 g sample of household bleach is completely reacted with ki(s). the resulting solution is then titrated with 0.150 m nas2o3 solution. 0.890 ml of the solution is required to reach the colorless endpoint. what is the mass percent of naocl (mm
There is 5.8 % of NaOCl in the sample.
The oxidation of hypochlorite is the first process, which goes as follows:
OCl^- + 2I^- + 2H^+ -----> I2 + Cl2 + H2O
Iodine and sodium thiosulfate react in the second stage as follows:
I2 + 2NaS2O3 -----> Na2S4O6 + 2NaI
Thiosulfate moles = 0.150 M * 0.890/1000 L = 1.335 * 10-4 moles.
Since 2 molecules of thiosulfate react with 1 mole of I2,
1.335 * 10-4 moles of thiosulfate and x moles of I2 react.
x = 1.335 * 10-4 moles/2 moles times one mole.
Iodine equivalent to 6.675 x 10-5 moles
6.675 * 10-5 moles of hypochlorite were reacted because 1 mole of hypochlorite yields 1 mole of iodine.
Therefore, the mass of NaOCl is equal to 4.97 * 10-3 g (6.675 * 10-5 moles * 74.44 g/mole).
5.8% of NaOCl is equal to 4.97 * 10-3 g/0.0854 g * 100/1.
NaOCl makes up 5.8% of the sample.
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What is the conjugate base of H2BO3- (I am confused because one has - and +. I dont understand which one the answer would be)
The conjugate base of a compound is what this compound will be after donating a H⁺.
The comopund in question is H₂BO₃⁻. After it loses 1 H⁺, it will have one less H atom and its charge decrease by one. Its charge is only with a "-" sign, which means its chargeis 1-. After decreasing by one, the charge becomes 2-.
So, the conjugate base will be HBO₃²⁻
which of the following will be the strongest oxidizing agent (weakest reducing agent)? a) chromium (0) b) chromium (ii) c) chromium (iii) d) chromium (iv) e) chromium (vi)
The strongest oxidizing agent is chromium (vi); option E.
What are oxidizing agents?Oxidizing agents are compounds that readily accept electrons and are reduced.
Oxidizing agents will oxidize other substances, resulting in an increase in the oxidation state of the compounds. However, they are themselves reduced as their oxidation states are reduced when they accept electrons.
Strong oxidizing agents are weak reducing agents.
Reducing agents readily give up electrons to other compounds, and hence are oxidized.
Transition elements are known for their variable oxidation states due to their ability to lose different numbers of electrons.
The higher the oxidation state of a transition element in a compound, the more oxidizing the compound will be.
Hence, a compound of a transition element in the highest oxidation state will be the most oxidizing.
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Put the following elements in order, with the element having the most valence electrons at the top of your list and the element with the fewest valence electrons at the bottom.swap_vertAstatine (At)swap_vertArsenic (As)swap_vertCalcium (Ca)swap_vertSodium (Na)swap_vertOxygen (O)swap_vertSilicon (Si)swap_vertAluminum (Al)
answer
1. Neon
2. Astatine
3. oxygen
4. Arsenic
5. Silicone
6. Aluminium
7. Calcium
8. Sodium
Which solution of the following has the lowest freezing point?
A. 40g of KBr dissolved in 200g of water
B. 30g of KBr dissolved in 100g of water
C. 20g of KBr dissolved in 250g of water
D. 10g of KBr dissolved in 100g of water
Pls do reply this answer with proper explanation.
Based on freezing point depression, the solution that has the lowest freezing point is 30g of KBr dissolved in 100g of water; option B.
What is freezing point depression?Freezing point depression is a phenomenon that occurs when a solute is dissolved in a pure solvent such as water.
When a solute is dissolved in a solvent, the freezing point depression is calculated using the formula below:
∆T = i * K * mWhere;
i = number of moles of ions produced
K = mola freezing point depression constant
m = molality
From the data given, i (same salt, KBr) and k are both constants.
Hence, the freezing point depression depends on the molality of the solution.
molality = moles / mass of solvent in Kg
Assuming moles = mass (since salt is the same)
Molality of A = 40 / 0.2 = 200 molal
Molality of B = 30 / 0.1 = 300 molal
Molality of A = 20 / 0.25 = 80 molal
Molality of A = 10 / 0.1 = 100 molal
Hence, solution B will have the highest freezing point depression.
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Why do we need to understand that reactions can happen at different speeds depending on the conditions?
We need to understand that reactions can happen at different speeds depending on the conditions to develop methods for production improvement.
The rate of any chemical reaction depends upon the nature of the reacting substances. Under the same conditions , reactions that appear similar have different rates of reaction. Chemical reaction proceeds in different speeds, depend on the various factors such as type of chemical transformation , temperature and other factors. the information about the speed of reaction is useful in large scale production.
Thus, We need to understand that reactions can happen at different speeds depending on the conditions to develop methods for production improvement.
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How many molecules are there in 4.00 moles of glucose, C6H1206?
Molecules in 4 moles of glucose are 24.088x10²³.
We need to find the number of molecules by applying the concept of moles
number of moles(n)= Number of Molecules(N)/Avogadro's Number(Nₐ)
n=N/Nₐ
4=N/6.022x10²³
N=24.088x10²³
Therefore, the number of molecules in 4 moles of Glucose is 24.088x10²³.
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Which group in the Periodic Table contains elements that are all gases?
1. 11
2. 17
3. 12
4. 18
Answer:
d
Explanation:
the group's name is called noble gases. hence they are all gases.
a student prepared an agno3 (aq) stock solution by dissolving an unknown mass of agno3 in a 250.00 ml volumetric flask and filling to the line with water. the student added 25.059 ml of the stock solution to a 500 ml volumetric flask and filled to the line with water to make 500 ml of a 9.443x10-3 m agno3 solution? what mass (in g) of agno3(s) did the student add to the 250 ml volumetric flask to make the stock solution?
Using the molarity of the final solution and the molar mass of silver nitrate, we can calculate that the student used 8.0015 g of silver nitrate to make the stock solution.
First, we calculate the number of moles in the 500.00 mL flask using the molarity (c) of the final solution and its volume (V = 500.00 mL = 0.50000 L).
c = n/V ⇒ n = c*V
n = 9.443 * 10⁻³ M * 0.50000 L
n = 4.7215 * 10⁻³ mol
This same number of moles was in the 25.059 mL solution that was subsequently diluted to 500.00 mL. Knowing this, we can make a simple proportion to calculate the number of moles present in the original 250.00 mL:
4.7215 * 10⁻³ mol : 25.059 mL = X : 250.00 mL
X = 4.7215 * 10⁻³ mol * 250.00 mL / 25.059 mL
X = 0.047104 mol
That's the amount (n) of silver nitrate used to make the stock solution. Now we can convert it to mass (m) by using the molar mass of silver nitrate (M = 169.87 g/mol):
n = m/M ⇒ m = n*M
m = 0.047104 mol * 169.87 g/mol
m = 8.0015 g
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which of the following pairs of aqueous solutions will form a precipitate when mixed? a) nh4no3 k2co3 b) hg2(no3)2 nabr c) kcl li3po4 d) agc2h3o2 cu(no3)2 e) none of the above solution pairs will produce a precipitate.
Hg2(NO3)2 NaBr will precipitate when combined in an aqueous solution without a catalyst at room temperature.
What is an aqueous solution?A solution that uses water as the solvent is said to be aqueous. It is frequently represented in chemical equations by adding to the relevant chemical formula.
To represent a solution of table salt, or sodium chloride, in water, the symbol Na+ + Cl can be used.
In an aqueous solution, liquid water acts as the solvent.
In other words, the ions and molecules that make up the solute (dissolved) are surrounded by the water molecules and incorporated into their web of connections.
The dissolved organisms then spread out across the water.
An aqueous solution is, to put it simply, anything that has dissolved in water.
The water sign represents (aq).
A substance that has been dissolved in water is called an aqueous solution.
Therefore, Hg2(NO3)2 NaBr will precipitate when combined in an aqueous solution without a catalyst at room temperature.
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pentaborane-9, bshg; is a colorless, highly reactive liquid that will burst into flame when exposed to oxygen. the reaction is 2bshg(l) 1202(g) sbzos(s) 9hzo(l) calculate the kilojoules of heat released per gram of the compound reacted with oxygen. the standard enthalpy of formation of shg is 73.2 kj mol.
The kilojoules of heat released per gram of the compound reacted with oxygen is -72.052 kj/g
The standard enthalpy of formation is a measure of the strength launched or fed on while one mole of a substance is created under trendy situations from its natural elements. The symbol of the standard enthalpy of formation is ΔH f. = A degree means that it's a fashionable enthalpy change.
Enthalpy of a formation refers to the trade in enthalpy for the formation of one mole of a substance from the maximum solid form of its constituent factors. change in enthalpy is symbolized by means of delta H and the f stands for formation.
Given,
compound ΔH°f
B₅H₉ 73.2
B₂O₃ -1271.94
H₂O -285.83
Balanced chemical equation:-
2B₅H₉ (l) + 12O₂ +(g) => 5B₂O₃ + 9H₂O(l)
From Hess's law
ΔH°min = Σ enthalpies of products - Σ enthalpies of reactants
= 5× (-1271.94) + 9×( -285.83) - 2(73.2) kj/mol
ΔH°min = -9078.59 kj/mol
It is seen that 2 moles of B₅H₉ react with O₂ is -9078.59 kj/mol
For 1 mole = -9078.59 kj/mol/2
= 4539.295 KJ/mol
The energy released per gram = energy released per mol/molar mass of B₅H₉
= 4539.295 kj/mol/63 g/mol
energy released per gram = -72.052 kj/g
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2. a. In general, how do the periodic properties of
the d-block elements compare with those of
the main-group elements?
b. Explain the comparison made in (a).
3. For each main-group element, what is the
relationship between its group number and
the number of valence electrons that the group
members have?
I will give Brainkist
The d block elements differ from the main group elements in the nature of the ions that they form. Also, the group number is related to the number of electrons in the valence sell of an atom.
What are the d block elements?The D block elements are those elements that are found to have d orbitals as the orbitals that has the highest energy in the atom. The d block elements are called the transition metals and they have an incompletely filled d - level.
Owing to the fact that d - level is incompletely filled they do exhibit variable oxidation states and are colored. On the other hand, the main group elements do not exhibit a variable oxidation states and the ions that they form are not colored.
Secondly, for each of the main group elements, the group number shows the number of valence electrons that are present in the outermost shell of the atoms in the elements of the groups.
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(a)one of the alkali metal reacts with oxygen forms solid white substance. when this substance is dissolved in water, the solution gives a positive test for hydrogen peroxide, h2o2. when the solution is tested in a burner flame, a lilac-purple flame is produced. what is the likely identity of the metal? (b) write a balanced chemical equation for the reaction of the white substance with water.
Answer: An ionic bond.
Explanation:An ionic bond is the force of attraction that holds together positive and negative ions. It forms when atoms of a metallic element give up electrons to atoms of a nonmetallic element. Ionic bonds form only between metals and nonmetals
boron has two naturally occurring isotopes: boron-10 (abundance 19.8%, mass 10.013 amu), boron-11 (abundance 80.2%, mass 11.009 amu). calculate the atomic mass of boron.
Answer:
Atomic mass of Boron: 10.8 amu
Explanation:
Boron-10: (0.198)(10.013) = 1.98 amu
Boron-11: (0.802)(11.009) = 8.83 amu
Add them up: 1.98+8.83= 10.8 amu
Please help How many moles of a gas sample are in 5.0 L container at 215 K and 342 kPa(The gas constant is 8.31 L kPa/mol K) Round your answer to one decimal place and enter the number only with no units.
Answer
1.0 mol
Explanation
Given:
Volume, V = 5.0 L
Temperature, T = 215 K
Pressure, P = 342 kPa
The gas constant, R = 8.31 L kPa/mol K
What to find:
The number of moles of the gas sample.
Step-step-solution:
The number of moles of the gas can be determine using the ideal gas equation formula:
[tex]PV=nRT[/tex]Put the given values into the formula and calculate for n:
[tex]\begin{gathered} 342\times5.0=n\times8.31\times215 \\ 1710=1786.65n \\ \text{Divide both sides by 1786.65} \\ \frac{1710}{1786.65}=\frac{1786.65n}{1786.65} \\ n=0.9571\text{ mol} \\ To\text{ one decimal place,} \\ n=1.0\text{ mol} \end{gathered}[/tex]The number of moles of the gas sample is 1.0 mol.
A compound conducts electricity in the solid state and does not dissolve in water. It isshiny and malleable. What type of bonding does it likely have?b. Ionicc. metallica.Covalent
Metallic solids,
the atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties. All exhibit high thermal and electrical conductivity, metallic luster, and malleability.
Answer: c. metallic
5. few spiders are
dangerous because they
are
Which two elements do not have a second energy level at all?
The two elements that do not have a second energy levels are Hydrogen (H) and Helium (He)
Energy levels are nothing but the 3-D spaces around the nucleus of an atom. The electrons revolve around the nucleus in their respective energy levels. Each energy levels can accommodate only a particular number of electrons.
For example, first energy level can accommodate only a maximum of 2 electrons whereas second energy level can accommodate 8 electrons.
Hydrogen has 1 electron and helium has 2 electrons around their respective nucleus. In both hydrogen and helium, electrons are accommodated in the first energy level.
Hence, the two elements that do not have a second energy levels are Hydrogen (H) and Helium (He)
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The pH of a 1.00 M solution of urea, a weak organic base, is 7.050.
Calculate the Ka of protonated urea.
The Ka value of a protonated base is the acid ionization constant. Which can be calculated from the concentration of H+ ion and the conjugate base. The ka value of protonated urea of the given pH is 7.92 ×10⁻¹⁵.
What is pH ?pH of a solution is the measure of its H+ ion concentration. It is says how much acidic or basic the solution is. If the pH value is 7, then the solution is neutral and if it is less than 7 the solution is acidic. pH value greater than 7 indicates that the solution is basic.
pH of a solution mathematically is the negative logarithm of H+ ion concentration. Given that the pH of urea solution is 7.050. Thus its H+ ion concentration is calculated as follows;
-7.050 = log [H+]
[H+] = antilog (-7.050)
= 8.9 × 10⁻⁸
Now when the protonated urea say it as HA is dissociated into its ions H+ and A-, then the ka value is written as;
[tex]Ka = \frac{[H+][A-]}{[HA]}[/tex]
Here, the [H+] and A- ion concentrations are equal and concentration of the solution HA is given 1 M.
Thus, Ka value of protonated urea can be calculated as follows:
Ka = (8.9 × 10⁻⁸)² / (1-[ 8.9 × 10⁻⁸])
= 7.92 ×10⁻¹⁵
Therefore, the acid ionization constant Ka of 1 M protonated urea with a pH of 7.050 is 7.92 ×10⁻¹⁵.
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a reaction involving acetic acid has an enthalpy change of 55.7 kj/mol. what is the concentration of 27.90-ml of this acetic acid solution if the reaction it is involved in evolves 716.12-j of heat?
not gon find it here cuh
Explanation:
The concentration of the acetic acid solution is approximately 0.0128 mol/L, given the information provided.
To determine the concentration of the acetic acid solution, we need to use the given enthalpy change and the heat evolved in the reaction.
The enthalpy change (ΔH) is given as 55.7 kJ/mol, which represents the heat released or absorbed per mole of acetic acid involved in the reaction.
The heat evolved in the reaction is given as 716.12 J. However, we need to convert it to kilojoules to match the unit of the enthalpy change. There are 1000 J in 1 kJ, so 716.12 J is equal to 0.71612 kJ.
Now, we can set up a proportion to find the concentration of the acetic acid solution. The heat evolved is directly proportional to the moles of acetic acid involved in the reaction, which is in turn proportional to the concentration of the solution.
Let's assume the concentration of the acetic acid solution is c mol/L.
The proportion can be set up as:
ΔH (kJ/mol) / Heat evolved (kJ) = 1 mol / c L
Substituting the values we have:
55.7 kJ/mol / 0.71612 kJ = 1 mol / c L
Simplifying:
c = 1 mol / (55.7 kJ/0.71612 kJ)
c ≈ 0.0128 mol/L
Therefore, the concentration of the acetic acid solution is approximately 0.0128 mol/L, given the information provided.
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what do sanding a piece of wood and rain forming into a cloud have in common
As a result, it is a natural bodily alteration. The chemical shape of the material is affected by physical changes, but not its makeup.
What kind of change is cloud formation?Since natural water undergoes a phase transformation cycle from liquid to gas and back to liquid, the production of clouds is a physical shift.
The physical conversion of water from vapour to liquid during cloud formation is known as condensation. When water evaporates during the evaporation process and condenses in the air to form clouds, there is a physical shift that takes place.
Condensation is the process by which water transforms from a gas to a liquid, whereas deposition is the process by which a gas transforms straight into a solid. Clouds are created by these two processes.
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what is the L W H OF THIS CUBE
Answer:
This is NOT a CUBE..
now Considering that one side of one small block is equal to 1 unit.
Then
Length = 3 units
Width = 3 units
Height = 4 units
Please tell me if this is correct
Length would be 3 units, Height is 4 units, and Width is I want to say 5 or 6 not truly sure
Can someone help me pls, i have like another 3 questions like this .-.
Answer:
1st box: Potential
2nd box: Electrical
3rd box: Kinetic
Explanation:
(1st box) Potential because the energy is stored and ready to act, which is definitely something desired for a battery.
(2nd box) Chemical, as discussed in the comments
(3rd box) Kinetic because the stored, potential energy is now 'acting' or 'in motion', causing it to be kinetic energy.
Answer:
Batteries store potential chemical energy
That the swith releases it into kinetic energy to light the room.
Explanation:
Energy comes in two main forms:
Kinetic energy which is energy of moving object or motion.2. Potential energy which is energy stored in object to be realesed to make effect. It can be stored in form of
Chemical energy. This can be in fuels or food taken by human body or the battery. Gravitational energy. This is due to the gravity and the force pulling the object from a height. Elastic energy. It is energy stored in rubber bands and spring balances.And there is much more....
Principle of conservation of energy says energy is not created nor destroyed but transferred from and object to another in different forms.
Five liters of hydrogen gas are stored at a pressure of 400
torr. If the temperature does not change, what will be the
volume of the gas when the pressure is decreased to 250
torr?
Five liters of hydrogen gas are stored at a pressure of 400 torrs. If the temperature does not change, then the volume of the gas would be 8 liters when the pressure is decreased to 250 torrs.
What is an ideal gas?It is an imaginary gas for which the volume occupies by it is negligible, this gas does not exist in a practical situation and the concept of an ideal gas is only the theoretical one,
Using the Boyle's law for the given problem,
P₁V₁=P₂V₂
400 × 5 = 250 × V₂
V₂ = 400 × 5 / 250
= 8 Litres
Thus, if the temperature does not change the volume of the gas would be 8 Litres.
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which of the following properties is typically used to identify whether a bond is polar, nonpolar, or ionic? a. atomic mass. b. electronegativity. c. atomic radius. d. ionization energy.
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Sodium and lithium have similar chemical properties. What characteristics of these elements explain why they are chemically similar?.
Sodium and lithium have similar chemical properties because both sodium and lithium have one valence electron
Chemical properties is the characteristics of particular substances that can be observed in a chemical reaction and the valence shell electrons in an atom determine the way it will interact with neighboring atoms and therefore determine its chemical properties and both sodium and lithium have one valence electron they share similar chemical properties and element sodium and lithium belong to group IA of the periodic table and the main characteristics is the a single electron in their outermost shell
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What is the density of an object with a mass of 24.6 g and a volume of 7.5 mL?
The density of an object is 3.52g/cc
What is density ?
The density of a substance indicates how dense it is in a given area. Mass per unit volume is the definition of a material's density. In essence, density is a measurement of how closely stuff is packed. It is a particular physical characteristic of a specific thing. The Greek scientist Archimedes made the discovery of the density principle. If you are familiar with the formula and the relevant units, calculating density is simple. Density is represented by the symbol, alternatively it can be written as the letter D.
d = M/V
d = density
M = mass
V = volume
d = 26.4/7.5 = 3.52g/cc
The density of an object is 3.52g/cc
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aldol condensation is an easy way of making: group of answer choices carbon-carbon bond carbon-oxygen bond carbon-nitrogen bond carbon-hydrogen bond all of these bond types
Aldol condensation is an easy way of making carbon-carbon bond.
In the field of chemistry, we can describe aldol condensation as a type of bond that occurs due to electrophilic substitution at the alpha carbons of the enol.
Aldol condensation is known to be the easiest way for one carbon to form bonds with another carbon.
Such an aldol reaction that takes place between carbonyl compunds instead of aldehydes or enols is referred to as crossed aldol condensation.
Aldol reactions are known to be an important part of synthesizing organic compounds as carbon-carbon bonds are formed due to it.
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Using the table of average bond energies, determine the total bond energy for the reactants in the combustion of ethene: C2H4 + 3 O2 --> 2 CO2 + 2 H2O
Explanation:
Hydrogen bonds with carbon 4 times, carbon bonds with itself once, and oxygen bonds with itself 3 times.
Energy of reactants:
E = 4 * 413 + 347 + 3 * 495
= 3484kJ/mol
Answer:
Energy transferred in = 3484kJ/mol
a major component of gasoline is octane . when octane is burned in air, it chemically reacts with oxygen gas to produce carbon dioxide and water . what mass of carbon dioxide is produced by the reaction of of octane?
8.70 g of carbon dioxide are generated by the reaction of octane.
Let's compile all the data in one location since we are aware that we will require a balanced equation with masses and molar masses.
M_r: 32.00 44.01
2C₈H₁₈ + 25O₂ ⟶ 16CO₂ + 18H₂O
m/g: 9.88
(a) Calculate the moles of O₂
n = 9.88 g O₂ ×1 mol O₂ /32.00 g O₂
n = 0.3088 mol O₂.
(b) Calculate the moles of CO₂
(16 mol CO2 to 25 mol O2) is the molar ratio.
n = 0.3088 mol O₂ × (16 mol CO₂/25 mol O₂)
n = 0.1976 mol CO₂
(c) Calculate the mass of CO₂
Mass of CO₂ = 0.1976 mol CO₂ × (44.01 g CO₂/1 mol CO₂)
Mass of CO₂ = 8.70 g CO₂
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