The molarity of the barium hydroxide solution is 0.065M.
How to calculate molarity?Molarity is the concentration of a substance in solution, expressed as the number moles of solute per litre of solution.
The molarity of a substance can be calculated using the following formula:
CaVa = CbVb
Where;
Ca = initial concentrationCb = final concentrationVa = initial volumeVb = final volumeAccording to this question, an aqueous solution of barium hydroxide is standardized by titration with a 0.170 M solution of nitric acid. If 27.2 mL of base are required to neutralize 10.4 mL of the acid, the molarity of the barium hydroxide solution can be calculated as follows:
0.170 × 10.4 = Cb × 27.2
1.768 = 27.2Cb
Cb = 0.065M
Therefore, 0.065M is the molarity of the barium hydroxide solution.
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Calculate the final concentration of a solution created through the following process: 1.7 L of a 2.4 M NaF solution is diluted with water to 3.3 L of NaF solution.
The final concentration of the diluted solution of NaF is equal to 1.24 M.
What is the dilution law?The concentration and the volume of the stock solution or dilute solution can be determined from the following equation:
M₁V₁ = M₂ V₂
where M₁ and V₁ are the concentration and volume of the stock or concentrated solution respectively and M₂ and V₂ are the concentration and volume of the diluted solution.
Given, a stock solution of NaF of concentration, M₁ = 2.4 M
The concentration of the diluted solution of NaF is M₂.
The volume of the concentrated solution of NaF, V₁ = 1.7 L
The volume of diluted solution of NaF, V₂ = 3.3 L
Substitute the value of the concentration and volume of NaF in equation (1):
(2.4)× (1.7) = M₂ × (3.3)
M₂ = 1.24 M
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Please answer correctly, I’ll mark your answer as brainliest.
Answer:
See explanation
Explanation:
3. so the three metals are Cu, Zn, and Fe (i'm assuming based off of the other answers)
A metal (M1) more reactive than the one in solution (M2) will swap places, precipitating M2 out and M1 will dissolve in solution.
So as an example, Zinc is more reactive than Copper, so Zinc metal will displace Copper 2+ in solution, giving Copper metal and Zinc 2+ in solution
The metal ion in solution is Zn2+, which is a pretty reactive metal. We know that a metal has to be more reactive than Zn to turn Zn2+ into Zn. This means that any metal which produces a change when allowed into contact with Zn2+ would have to be very reactive.
The three metal wires are: Cu, Zn, and Fe
Cu is not more reactive than Zn, so no reaction will occur between Cu and Zn2+.
Fe is not more reactive than Zn, so no reaction between Fe and Zn2+
Zn is well... as reactive as Zn, so there will also be no reaction (because there is no incentive for change, no change happens)
Thus, number 3 will have an answer of "No reactions were observed, and no spontaneous chemical equations can be written" (Though zinc does react with water very slowly. Also, if the ZnCl2 was contaminated with acid, the Zinc wire may have formed some bubbles )
For number 4, it is the same logic. But it is also a little more complicated.
The metal in solution is Fe3+. The wires are Zn, Fe, and Cu
The annoying (or cool, depending on how you look at it) thing about Fe3+ is that it can be reduced to either Fe2+(aqueous), or all the way to Fe(solid).
depending on how much reactant is added and what exactly that other reactant is.
From this point on, instead of saying "Because Zn is more reactive than Fe..." I'll say "Because Zn turning into Zn2+ is more favourable than Fe turning into Fe3+" or something of the sort. Hopefully It doesn't become too confusing. Please ask questions in the comments
Zn turning into Zn2+ is much more favorable than Fe turning into Fe3+, so the Zn will react with Fe3+, turning it into Fe and giving Zn2+ (Charges are not balanced)
So Zn(s) + Fe{3+}(aq) -> Zn{2+}(aq) + Fe(s)
and balance it to get
3Zn(s) + 2Fe{3+}(aq) -> 3Zn{2+}(aq) + 2Fe(s)
Fe may seem like it would not react with Fe3+ since they both are iron. However Fe2+ exists, and since Fe2+ turning into Fe3+ is unfavourable (meaning that Fe3+ is a stronger oxidant) and Fe turning into Fe2+ is favourable, the following reaction happens:
Fe(s) + 2 Fe{3+}(aq) -> 3Fe{2+}(aq)
In this reaction, each iron metal atom gives two iron 3+ ions one electron, loosing 2 electrons itself in the process and turning into Fe2+. The two iron 3+ ions given one electron also turn into Fe2+ ions, resulting in 3 Fe2+ ions total
Copper is fairly unreactive, and while FeCl3 is technically reactive enough to react with copper, forming FeCl2 and CuCl, the CuCl layer prevents underneath copper from reacting further.
Which statements correctly defend or dispute his conclusion?
The statement that correctly defend or dispute his conclusion is option3:
He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.Is salt and water evaporation a physical or chemical change?A physical alteration occurs when salt water evaporates. Since the matter has merely changed states but still remains the same substance, any phase shift is a physical change.
Table salt dissolving in water is an example of a physical change because only the condition of the substance has changed. Frequently, physical changes can be undone. The salt will become solid once the water has evaporated.
It's not a given that salt and water's formation of a single phase indicates a chemical reaction. It simply indicates that the two substances mixed evenly.
Therefore, This is supported by the fact that the mixture's components could be easily separated using a straightforward physical technique called evaporation.
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See full question below
Henry mixed salt and water together in a cup until he observed a clear solution. He measured the mass of the solution. Then he placed the cup outside for several sunny days during the summer. After a week, he observed that only solid salt remained in the cup and the mass had decreased. Henry concluded that a physical and chemical change occurred in this investigation.
Which statements correctly defend or dispute his conclusion?
1- He is correct. Dissolving salt in water is a physical change, but evaporating the water is a chemical change. Formation of a solid is evidence that a chemical change occurred.
He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.
2- He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.
3- He is incorrect. Dissolving salt in water and evaporation of the water are both chemical changes. The reappearance of salt is evidence that the change was reversible by a chemical change, so it could not be a physical change.
1. Target I1
Which list of elements all have the same number of valence electrons?
a. F, CI, O, N
b. Cr, Mn, Fe, Co
C. Ne, Ar, Kr, Xe
d. Na, Mg, Al, Si
Answer:
A
B that is Cr,MN,Fe,Co. is the correct answer
C
D
pretend you are a journalist assigned to write about an atom from the prestigious periodic table.
The answer to the task from above about the an atom of element periodic table is given below:
The chlorine atom is one of the halogens in the periodic table.
Why the chlorine atom is an halogen of prestigious periodic tableRight from time immemorial, the indepth knowledge and understanding of how atoms are arranged in the periodic table and react with with each speaks volume of the identities of the properties of elements.
Chlorine is regarded as an halogen simply because they are salt formers when it atoms react with alkali metals.
So therefore, it can be deduced that the periodic table is the heart of chemistry.
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What is the Lewis structure, (sketch 3D also), total # of electrons, electron geometry, hybridization and polarity for the following
A Lewis Structure can be defined as a very simplified representation of the valence shell electrons in a molecule. It explains how the electrons are arranged around individual atoms in a molecule.
Explain different terms mentioned above.
Lewis Structure :It was named after Gilbert N who mentioned it for the first time in his book The Atom and the Molecule.
The Lewis Structure can be written as follows:
Step 1: Determine total valence electrons.
Step 2: Write the skeleton structure of the molecule
Step 3: Form bond in the skeleton structure using two valence electrons.
Step 4: Fulfil octet rule and segregate non bonding electrons.
Examples : In case of CO2, we can see
two double bonds between the carbon and oxygen atoms. According to octet rule each oxygen atom needs to bond with four different carbon atoms. Carbon has four valence electrons, which make a total of four bonds. So there are four dots around carbon.
Electron geometry : It can be defined as the arrangement of electron pairs around a central atom. It can be given in such form :
linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral
Hybridisation : It can be defined as the intermixing of two atomic orbitals to give rise to new hybridized orbitals. The hybrid orbitals formed have entirely different energies, shapes, etc.
Polarity : It can be defined as the distribution of electrical charge over the atoms joined by the bond.
Hence, structure can be determined by knowledge of these factors.
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What is the answer for this question?
Answer:
See explanation, some might be graded as wrong if it's an automatic grading system but most
Explanation:
1. lose
2. valence
3. noble (Atoms don't actually always do this, but since the word gas is after the blank, it is the only option)
4. 4
5. have
6. 10
5 and 6 are a little ambiguous and could have many answers
The solubility of lead (II) chloride (PbCl2) is 1.6 × 10-2 M. What is the Ksp of
PbCl2
.
The solubility constant (Ksp) of lead (II) chloride if it has a molar concentration of 1.6 × 10-²M is 1.64 × 10-⁵.
How to calculate solubility constant?Solubility is the amount of a substance that will dissolve in a given amount of a solvent, to give a saturated solution, under specified conditions.
PbCl₂(s) ⇌ Pb²⁺(aq) + 2Cl¯(aq)
The Ksp expression of lead chloride is as follows:
Ksp = [Pb²+] [Cl¯]²
There is a 1:1 molar ratio between PbCl₂ and Pb²⁺ but a 1:2 molar ratio between PbCl₂ and Cl.
Ksp = {1.6 × 10-²} {3.2 × 10-²}²
Ksp = 1.64 × 10-⁵
Therefore, 1.64 × 10-⁵ is the solubility constant of the lead (II) chloride.
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In N2O, nitrogen is the central atom and the oxygen atom is terminal. In HSCN, however, nitrogen is the terminal atom.
Draw four Lewis structures corresponding to HSCNwith C as the central atom,
HSCN with N as the central atom,
N2O with N as the central atom, and
N2O with O as the central atom.
Use formal charges for each of these four Lewis structures to explain why nitrogen is the central atom of N2O
but carbon is the central atom of HSCN
Match the items in the left column to the appropriate blanks in the sentences on the right.
The Lewis structures of the compounds have been shown. In each case, the least number of formal charge lies on nitrogen hence it is the central atom.
What are Lewis structures?The term Lewis structures help us to be able to see what a molecule looks like. We know that the Lewis structures show the symbol of the element and then the number of electrons that are in the atoms of the element as dots.
In this case we have shown the Lewis structures of the compounds that are shown. The formal charges of the compounds are also shown in the image that is described here.
Looking at the Lewis structure as it has been shown, we can see that nitrogen always has the least charge density hence we can see that nitrogen would always be the central atom in the compounds as shown.
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Morphine is used medicinally as a pain reliever. If an aqueous solution of morphine has [H3O+] = 1.1 x 10-10 M, what is the pH of this solution?
Morphine is used medicinally as a pain reliever. If an aqueous solution of morphine has [H3O⁺] = 1.1 x 10-10 M, the pH of this solution is 9.6.
given that :
[H3O⁺] = 1.1 x 10-10 M
the pH of the solution is given as :
pH = - log ( [H3O⁺] )
pH = - log ( 1.1 x 10-10 M )
pH = - (-9.6 )
pH = 9.6
the pH of the given solution is 9.6.
Thus, Morphine is used medicinally as a pain reliever. If an aqueous solution of morphine has [H3O+] = 1.1 x 10-10 M, the pH of this solution is 9.6.
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A light emitting diode will emit light when
A) A hole jumps to the conduction band.
B) A hole jumps to the valence band.
C) An electron hops between orbitals in the conduction band.
D) An electron gives up energy when it falls into the valence band to fill a hole.
The answer is D. When an electron falls into the valence band to fill a hole, it gives up energy in the form of light.
The diode in an LED bulb is a semiconductor device that allows electricity to flow in one direction only. It is made of two pieces of semiconductor material, one positive and one negative, that are joined together.
The diode in the process of electrolysis has two terminals, called the anode and the cathode. The anode is the positive terminal and the cathode is the negative terminal in the electrolysis. The anode is connected to the positive terminal of the power supply and the cathode is connected to the negative terminal of the power supply.
When the power is turned on, the diode allows electricity to flow from the anode to the cathode and lights up the LED bulb.
The light-emitting diode will emit light when an electron jumps from the conduction band to the valence band. This is because when the electron falls into the valence band, it will release energy in the form of light.
Therefore the correct option is d.
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Which element needs 3 valence electrons to complete its octet?
Answer: Gallium
Explanation:
Lead(II) nitrate and ammonium iodide react to form lead(II) iodide and ammonium nitrate according to the reaction
Pb(NO3)2(aq)+2NH4I(aq)⟶PbI2(s)+2NH4NO3(aq)
What volume of a 0.650 M NH4I solution is required to react with 319 mL of a 0.660 M Pb(NO3)2 solution?
volume:
mL
How many moles of PbI2 are formed from this reaction?
moles:
mol PbI2
The volume of the lead II iodide required is 649 mL.
What is the required volume?We know that the volume can be obtained by the use of the stoichiometry of the reaction. In this case, we have been given the balanced reaction equation as it appears in the question above. We now have to use it and find the volume as the question must have required.
Thus;
Number of moles of the lead II nitrate = 0.660 M * 319/1000 L
= 0.211 moles
Now we have to recall again that the number of moles is obtained as the product of the concentration and the volume of the solution.
Using the stoichiometry of the reaction;
1 mole of the lead II nitrate reacts with 2 moles of the ammonium iodide
0.211 moles of the lead II nitrate reacts with 0.211 moles * 2 moles/ 1 mole
= 0.422 moles
Now;
Volume of the solution = number of moles/ concentration
= 0.422 moles/0.650 M
= 0.649 L or 649 mL
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Reactions in our world: pre-lab activity worksheet
When iron ( Fe ) reacts with copper sulphate ( CuSO₄) , it forms ferrous sulphate ( FeSO₄ ) and copper ( Cu ) .
Iron copper sulphate.
The lead nitrate [Pb(NO₃)₂] reacts with potassium iodide (Kl) causing exchange of ions between the reactants leading to the formation of potassium nitrate (KNO₃) and a yellow precipitate of lead iodide (PbI₂).
Magnesium reacts with hydrochloric acid according to the equation
Mg + 2 HCl --> MgCl₂ + H₂
Magnesium reacts with hydrochloric acid according to the equation This demonstration can be used to illustrate the characteristic reaction of metals with acid, a single replacement reaction, or to demonstrate the generation of hydrogen gas.
H₂O
Water splitting is the process in which water decomposes into hydrogen and oxygen.
Mg + O₂ → MgO.
Magnesium reacts with Oxygen to form Magnesium oxide.
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A digital signal transmits energy in the form of waves. These waves can travel at the speed of light. Only digital information can be read and scratches or other imperfection are not read. Which conclusion would be best based on this information? Responses ADigital transmission of information is not likely to be replace other methods. Digital transmission of information is not likely to be replace other methods. BDigital transmission of information is the least expensive method. Digital transmission of information is the least expensive method. CDigital transmission of information is a fast and reliable method. Digital transmission of information is a fast and reliable method. DDigital transmission of information can easily be converted to analog.
Since the A digital signal transmits energy in the form of waves, the conclusion that would be best based on this information is option C: Digital transmission of information is a fast and reliable method.
All electromagnetic waves constitute digital signals?Signals, both digital and analog, are transferred via electromagnetic waves. The sound you hear or the graphics you see on a screen are the result of changes in frequency and amplitude. The continuous waves that make up analog signals can be of any frequency and amplitude.
Note that Data transfer, also known as digital transfer or digital communication, is the movement of data between two locations. Digital messages from a data source, such as a computer or keyboard, may be the source of the transmitted data. A phone call or a video signal are examples of analog signals that could also be present.
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Which part of Earth experiences physical weathering? (1 point)
O crust
O mantle
O inner core
O outer core
0
A
O
It is popularly known that C1V1=C2V2 can be useful during reagent/solution preparation. Given that 8ml of 5.2m NaCL would be needed to prepared 0.231m NaCL . How would the formula above be used to determined the volume of flask for the preparation?
The volume of the flask for the preparation of 0.231M solution can be 200ml flask. The equation C1V1 = C2V2 is used for the dilution of the samples.
What is dilution?
Dilution is a process in which a solution is made less concentrated by adding some other constituent to it. To dilute a solution more solvent should be added than the solute. The number of ions of solute remains the same but the volume is increased so the concentration decreases.
For the dilution using,
C1V1 = C2V2
5.2M x 8ml = 0.231M x V2
V2 = 5.2M x 8ml / 0.231M
V2 = 180.08ml.
Therefore, 180.08ml of new solution is made through dilution for which me need 200ml flask or higher volume flasks.
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The decomposition of KClO3 is generally used to prepare small amounts of O2 in the
laboratory. How many grams of O2 can be prepared from 8.50 g of KClO3?
The number of grams of oxygen that can be prepared from 8.50g of pottasium chlorate is 3.33grams.
How to calculate mass?Stoichiometry is the study and calculation of quantitative (measurable) relationships of the reactants and products in chemical reactions (chemical equations).
According to this question, the decomposition of KClO₃ is generally used to prepare small amounts of O₂ in the laboratory.
2KClO₃ → 2KCl + 3O₂
Based on the above equation, 3 moles of oxygen is produced by the decomposition of 2 moles of pottasium chlorate.
8.50grams of KClO₃ is calculated in moles as follows: 8.50g ÷ 122.55 g/mol = 0.069mol of KClO₃.
This means that 0.069 × 1.5 = 0.104 moles of oxygen is produced.
mass of oxygen produced = 0.104 × 32 = 3.33grams.
Therefore, 3.33grams is the mass of oxygen formed.
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For the given reaction, what volume of O₂ would be required to react with 6.2 L of NO, measured at the same temperature and
pressure?
2 NO(g) + O₂(g) → 2 NO₂(g)
O2 would need to react in 3.1 L of volume.
Given data:-2NO(g) + O2(g) ==> Equation that is balanced: 2NO2(g)
We can observe that 2 moles of NO react with 1 mole of O2 using this equation. We can also state that 2 liters of NO and 1 liter of O2 react under conditions of constant pressure and temperature. The amount of O2 required to react with 4.8 L of NO can then be calculated as follows:
6.2 L NO multiplied by 1 L O2 divided by 2 L NO results in a need for 3.1 L of O2.
2NO O2 2NO2: What kind of reaction is that?values for the reaction 2NO + O2 = 2NO2 in terms of kinetics and rate constants. It is generally known that this reaction is a third-order homogeneous reaction.
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A maggot is another name for—-
another name for a maggot is a worm
This bohr model is showing what element?
15 P
16 N
Answer:
Phosphorus
Explanation:
From the Bohr model of the given element we can interpret that:
Total number of electron = 15
Total number of proton = 15
Total number of neutron = 16
So, Mass of the element= Total number of proton+ Total number of electron
= 15 + 16
= 31 u
An atom that has 15 electron and mass have mass 31 amu is Phosphorus
What is the mass of 6.02 x 10^^24
molecules of hydrogen, H2? The molar
mass of H2 is 2.02 g/mol.
A- 2.02 g H2
B- 2.98 x 10^24 g H2
C- 10.0 g H2
D- 1.22 x 10^25 g H2
Mole measures the number of elementary entities of a given substance that are present in a given sample. The mass of hydrogen is 20.2gram.
What is mole?The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity of amount of substance.
Given number of atoms= 6.02 x 10²⁴atoms
we know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number
mole =given number of atoms ÷ 6.022×10²³(Avogadro number)
Substituting the values
mole=6.02 x 10²⁴÷ 6.022×10²³
mole = 10 mole
Mole = mass ÷Molar mass
Molar mass = 2.02 g/mol
Substituting the given values
10= mass ÷ 2.02 g/mol
Mass = 20.2gram
Therefore, mass of hydrogen is 20.2gram.
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When 2 moles of H₂S(g) react with
O₂(g) to form H₂O(g) and SO₂(g)
according to the following equation,
1.04×10³ kJ of energy are evolved.
2H₂S(g) + 30₂(g)→→→→→→
2H₂O(g) + 2SO₂(g)
Is this reaction endothermic or
exothermic?
What is the value of q?
kJ
The reaction is exothermic in nature and the value of q in kJ is -1.12x10^3 kJ
The reaction is 2H₂S(g) + 3O₂(g)→→→→→→2H₂O(g) + 2SO₂(g)
The amount of heat evolved in the reaction = 1.12 X 103 KJ
2 moles of hydrogen sulphide react.
In an is In an endothermic reaction, energy is consumed. an exothermic reaction, energy evolved Thus, the given reaction is exothermic.
Exothermic reactions are those reactions in which the energy is evolved or released by the reaction.
And endothermic reactions are those reactions in which heat or energy is absorbed in the reaction.
Since the reaction is evolving energy.
Hence the reaction is an exothermic reaction.
The value of q is defined as the amount of heat transferred to the system.
Since the heat is going away from the system.
Hence the value of q will be -ve.
And the magnitude of q will be exactly the same as the amount of heat evolved by the reaction.
Hence q = -1.12 X 103 KJ (-ve sign shows that heat is being evolved i.e exothermic process)
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4.00g of iron was was heated from 25.0°C to 75.0°C. How much energy was used to heat the iron
The energy used to heat the iron from 25°C to 75°C will be 88J
Given,
m= 4 g
c, i.e, specific heat of Iron is 0.44 J°C⁻¹g⁻¹
The heat energy is given by formula,
q=mcΔT
where q is the amount of heat and m is the substance's mass.
T represents the temperature change, and c is the material's specific heat capacity. The addition of heat affects various substances in varying degrees. Different materials' temperatures rise by different amounts when a given amount of heat is applied to them.
q =4× 0.44× ΔT
ΔT= T₂₋ T₁
ΔT= 75- 25
= 50°C
q= 4×0.44×50
=88 J
So, the energy used to heat the iron will be 88J.
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Answer Options:
atomic number
atomic mass
element symbol
element name
electron configuration
Answer:
1) atomic number
2) element symbol
3) element name
4) atomic mass
5) electron configuration
If I take my break at 3:48 and break our 30 mins what time is my break over
Answer:
Your break would end at 4:18
Explanation:
this bohr model is showing what element
The image shows the Bohr model of the chlorine atom.
What is the Bohr model?We know that the Bohr model has to do with the model in which the electrons that are in the atoms are arranged in a definite order. The implication of this is that the electrons would be arranged in a certain specific energy level such that an electron can be moved from a lower to a higher energy level as we can see from the image that has been shown in the question that has been asked.
Having said that we have seventeen protons in the atom and the implication is that there are also seventeen electrons in the atom and this is going to correspond to the element chlorine atom which can be shown to be a member of the group seventeen of the periodic table of the elements.
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What is the photon energy of a wave with a frequency of 6.7 x 1014 Hz?
Answer:
4.4 x 10⁻¹⁹ J
Explanation:
To find the energy of the photon, you need to use the following equation:
E = hf
In this equation,
-----> E = energy (J)
-----> h = Planck's Constant (6.626 x 10⁻³⁴ J·s)
-----> f = frequency (Hz)
You can plug the given value and constant into the equation and solve for "E". The final answer should have 2 sig figs like the given value (6.7 x 10¹⁴ = 2 sig figs).
E = hf <----- Given equation
E = (6.626 x 10⁻³⁴ J·s)(6.7 x 10¹⁴ Hz) <----- Insert values
E = 4.4 x 10⁻¹⁹ J <----- Multiply
A 0.7256 g mixture of KCN ( MW=65.116 g/mol ) and NaCN ( MW=49.005 g/mol ) was dissolved in water. AgNO3 was added to the solution, precipitating all of the CN− in solution as AgCN ( MW=133.886 g/mol ). The dried precipitate weighed 2.5874 g. Calculate the weight percent of KCN and NaCN in the original sample.
The weight percent of KCN and NaCN in the original sample are;
weight percent of KCN = 57%weight percent of NaCN = 43%What is the weight percent of KCN and NaCN in the original sample?The weight percent of KCN and NaCN in the original sample is calculated as follows:
The mass of the original mixture of KCN and NaCN = 0.7256 g
The dissociation equation of the ionic compounds in an aqueous solution is given below:
KCN ⇄ K⁺ + CN⁻
NaCN ⇄ Na⁺ + CN⁻
Mass of precipitate of AgCN = 2.5874 g
Moles of AgCN in a 2.5874 g sample = mass / molar mass
molar mass of AgCN = 133.886 g/mol
Moles of AgCN in the sample = 2.5874 / 133.886
Moles of AgCN in the sample = 0.01932 moles
Moles of CN⁻ in the sample = 0.01932 moles
Mass of CN⁻ present in the sample = 0.01932 * 26
Mass of CN⁻ present in the sample = 0.50232 g
Moles of Na⁺ present = 0.01932 / 2 moles
Moles of Na⁺ present = 0.009663 moles
Mass of Na⁺ present = 0.00966 * 23
Mass of Na⁺ present = 0.2222 g
Moles of K⁺ present = 0.01932 / 2 moles
Moles of K⁺ present = 0.00966 moles
Mass of K⁺ present = 0.009663 * 39
Mass of K⁺ present = 0.3768 g
Mass of sample = 0.50232 g + 0.2222 g + 0.3768 g
Mass of sample = 1.10132 g
weight percent of KCN = (0.3768 + 0.50232/2)/1.10132 * 100%
weight percent of KCN = 57%
weight percent of NaCN = (100 - 57)%
weight percent of NaCN = 43%
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Given the thermochemical equations
X₂ + 3 Y₂ → 2XY3 ΔH1= -340kJ
X₂ + 2Z₂ → 2XZ₂ ΔH2= -170 kJ
2Y2 + Z2 → 2Y₂Z ΔH3= -260 kJ
Calculate the change in enthalpy for the reaction.
4XY3 +7Z₂ → 6Y₂Z + 4 XZ₂
ΔH= ____ kJ
The change in enthalpy for the reaction is ∆H = - 440 kJ
This Enthalpy equals the sum of the system's internal energy with the constant. You must understand that energy forms change, but Enthalpy remains constant. For example, when water freezes into ice, some energy is expended in doing the work, which is referred to as Enthalpy.
Given that:
(1) X2 + 3Y2⟶ 2XY3 Δ1=−340 kJ
(2) X2 + 2Z2⟶ 2XZ2 Δ2=−170 kJ
(3) 2Y2 + Z2⟶ 2Y2Z Δ3=−260 kJ
We have to calculate the change in enthalpy for 4XY3 + 7Z2 → 6Y2Z + 4XZ2
The enthalpy of the reverse reaction is lower than that of the forward one.
Hess law: It states that the heat of reaction for any specific reaction is equal to the sum of the heat of each reaction that sums up to the overall reaction.
The required equation 4XY3 + 7Z2 → 6Y2Z + 4XZ2 is obtained by
-2(equation1) + 2(equation 2) + 3 (equation 3)
Reversing equation(1) we get
2(XY3 → X2 + 3Y2) + 2 (X2 + 2Z2 ⟶ 2XZ2 )+ 3 (2Y2 + Z2⟶ 2Y2Z)
4XY3 + 2X2 + 4Z2 + 6Y2 + 3Z2 ⟶ 2X2 + 6Y2 + 4XZ2 + 6Y2Z
Canceling all the standard terms we get
4XY3 + 7Z2 ==> 4XZ2 + 6Y2Z
Hence the required equation is obtained
Thus the change in enthalpy of the required reaction is
2〖(∆H〗_rev) +2〖(∆H〗_2)+ 3〖(∆H〗_3)
∆H = 2〖(∆H〗_rev) +2〖(∆H〗_2)+ 3〖(∆H〗_3)
∆H = 2(340) + 2(-170) +3 (-260) = -350 kJ
∆H = 680 – 340 – 780
∆H = - 440 kJ
Therefore the change in enthalpy for the reaction is ∆H = - 440 kJ
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