Answer:
Theory
Explanation:
A proved hypothesis usually becomes known as a theory.
Let's take an example. Remember the experiment for the Newton's law of universal gravitation. In an experiment like this, we should have a reference point, a hypothesis. The thought process would be, for example, to intuitively propose that the force of gravity depends on the masses of the two objects and the distance between them.
As a second step, sufficiently high number of experiments should be performed to prove this relationship with different masses and different distances to see how force correlates with the given variables.
Having noticed that the two masses are directly proportional to force and that force is inversely proportional to the square of a distance between the two objects, a proportionality constant is also found, so then we have an equation which would help us solve for the force of gravity between any two objects knowing their masses and the distance between them.
Overtime, after this hypothesis is proved analyzing substantial data, it becomes an accepted theory that can be used and applied.
A hypothesis that is extensively supported by numerous experiments and evidence can become a scientific theory, which is a well-substantiated explanation for a set of observations.
Explanation:A hypothesis is a tentative explanation for scientific observations that seeks to put the system being studied into a testable form. When a hypothesis is supported through many experiments over an extended period, it can evolve into a well-substantiated explanation known as a scientific theory.
Scientific theories are broad explanations for events that are widely accepted as true because they have been thoroughly tested and are supported by a significant amount of evidence. For a hypothesis to become a scientific theory, it must consistently produce experimental results that agree with predictions, and it must withstand rigorous scrutiny. The process of experimental verification and any necessary modification of a hypothesis as part of its development into a theory is an essential aspect of the scientific method.
The emission spectrum of an element:
A. may be identical to the emission spectrum of another element.
B. is identical to its absorption spectrum.
C. may be identical to the absorption spectrum of another element.
D. is different from any other element's absorption spectrum.
B
The emission spectrum of an element is identical to its absorption spectrum.
Explanation:
This is because a quantum leap of an electron of an atom from one lower energy level to a higher one results in the absorption of a specific wavelength of electromagnetic radiation. When the electron leaps back to the lower energy level, it releases the same wavelength of electromagnetic radiation. This is according to Bohr's theory. Every atom has a signature absorption and emission spectra that are used to identify it.
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A Beer's law plot for Cu2+ was experimentally obtained. The slope of the Beer's law plot was 310 L/mol (with a y-intercept = 0.001). A Cu2+ solution of unknown concentration had an absorbance of 0.55. What is the molar concentration of Cu2+ in the unknown solution?
Answer:
[tex]1.7742\times 10^{-3} mol/L[/tex] is the molar concentration of Cu(II) ions in the unknown solution.
Explanation:
Using Beer-Lambert's law :
Formula used :
[tex]A=\epsilon \times C\times l[/tex]
where,
A = absorbance of solution
C = concentration of solution
l = length of the cell =
[tex]\epsilon[/tex] = molar absorptivity of solution
A Beer's law plot is between absorbance and concentration.
[tex]\frac{A}{c}=Slope(m)=\epsilon\times l[/tex]
We have:
A = 0.55
The slope of the Beer's law plot = m = 310 L/mol
So, the concentration of the solution is:
[tex]c=\frac{A}{m}=\frac{0.55}{310 L/mol}=1.7742\times 10^{-3} mol/L[/tex]
[tex]1.7742\times 10^{-3} mol/L[/tex] is the molar concentration of Cu(II) ions in the unknown solution.
Using Beer's law and the given slope and absorbance values, the molar concentration of Cu2+ in the solution is approximately 1.77 * [tex]10^{-3[/tex] M.
Explanation:Beer's law, also known as the Beer-Lambert law, establishes a linear relationship between the absorbance of a species in a solution and its concentration. The equation for Beer's law is A = εlc, where A is absorbance, ε is the molar absorptivity (given by the slope in this case), l is the path length (assumed to be 1 cm here), and c is the concentration. In your case, the slope is 310 L/mol, and you have measured an absorbance of 0.55.
To find the concentration of Cu2+ in the solution, we rearrange the Beer's law equation to c = A / εl. Substituting in your values, we get c = 0.55 / (310 L/mol * 1 cm), which simplifies to c = 0.00177 mol/L or 1.77 * [tex]10^{-3[/tex] M. So the molar concentration of Cu2+ in the unknown solution is approximately 1.77 * [tex]10^{-3[/tex] M.
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4.80 mol of solid A was placed in a sealed 1.00-L container and allowed to decompose into gaseous B and C. The concentration of B steadily increased until it reached 1.30 M, where it remained constant.
A(s) <===> B(g) + C(g)
Then, the container volume was doubled and equilibrium was re-established. How many moles of A remain?
Answer:
A = 3.5 moles
Explanation:
In order to do this, we need first to write the innitial conditions. The reaction is as follow:
A(s) <-------> B(g) + C(g)
From here, we can write an expression for the equilibrium constant which is:
Kc = [B]*[C]
We don't take A in the expression, because is solid, and solid and liquids do not contribute in the equilibrium.
We know the concentration of B, which is the same for C, because the moles of C are coming from A when it's decomposed, so if B is 1.3 M we can assume C is the same.
Kc for this innitial condition is:
Kc = (1.3)*(1.3) = 1.69
Now, in the second part of reaction the volume is doubled, which means that concentrations are halved:
A: 4.8/2 = 2.4 M
B and C: 1.3/2 = 0.65 M
So conditions for the second part will be like this:
A(s) <----> B(g) + C(g) Kc = 1.69
I: 2.4 0.65 0.65
C: -x +x +x
E: 2.4-x 0.65+x 0.65+x
Replacing in Kc we have:
1.69 = (0.65+x)² solving for x here
√1.69 = 0.65+x
1.3 = 0.65+x
x = 1.3 - 0.65
x = 0.65 M
Therefore, the remaining moles of A would be:
A = 2.4 - 0.65
[A] = 1.75 M
moles A = 1.75 * 2 = 3.5 moles
Addition of which disaccharide to a solution of Ag2O in NH3(aq) will NOT result in the deposition of shiny silver mirror on the walls of the reaction vessel?
Answer:
Saccharose
Explanation:
Disaccharide Saccharose is formed by glucose and fructose, both monosaccharides are bound by their anomeric carbons (O-glucosidic), this is, both reducing carbons form the O-glucosidic bond, hence, they are not available to reduce Ag⁺ to Ag⁰
Distinguishing ionic, molecular and atomic solids web activity
Answer:
The difference lies in the kind of bond involved.
Explanation:
An ionic solid is composed of a network of oppositely charged ions such as sodium chloride solid. An atomic solid is formed by covalent linkage of atoms of the same element to form a three dimensional solid structure such as in diamond and graphite. A molecular solid consists of discreet molecules held together by intermolecular forces. Examples of molecular solids include naphthalene and the fullerenes.
Final answer:
Crystalline solids are categorized into ionic, molecular, covalent network, and metallic solids, each with unique properties such as melting points and electrical conductivity. Understanding these categories helps predict material behaviors.
Explanation:
Understanding Crystalline Solids: Ionic, Molecular, Covalent Network, and Metallic
Crystalline solids are distinguished based on their bonding and structural properties. They fall into four main categories: ionic solids, molecular solids, covalent network solids, and metallic solids. Each type exhibits distinct properties in terms of melting point, electrical conductivity, solubility in water, and appearance.
Ionic solids are formed through the electrostatic attraction between ions, have high melting points, and conduct electricity only when melted or dissolved in water.
Molecular solids are composed of molecules held together by van der Waals forces, have relatively low melting points, and are poor conductors of electricity in all states.
Covalent network solids consist of atoms connected by covalent bonds into a continuous 3D network, have very high melting points, and typically do not conduct electricity.
Metallic solids are composed of metal atoms packed closely together, have variable melting points, and are good conductors of electricity and heat due to the free movement of electrons.
Solids can broadly be categorized into amorphous solids and crystalline solids, with the latter being further divided into the types discussed. Understanding these categories and their properties aids in predicting the behavior of different materials under various conditions.
Cesium frequently is used in photocells because its work function (3.43 × 10(to the -19th power) J) is the lowest of all the elements. Such photocells are ef cient because the broadest range of wavelengths of light can eject electrons. What colors of light will eject electrons from cesium? What colors of light will eject electrons from selenium, which has a work function of 9.5 × 10(to the -19th power) J?
Answer:
I have no idea how to do this question its hard for me
Explanation:
All colors of visible light can eject electrons from cesium due to its low work function. For selenium, only light towards the blue/violet end of the spectrum (short wavelength, high energy) can eject electrons due to its higher work function.
Explanation:The phenomenon discussed in question involves the photoelectric effect, which occurs when light of a certain wavelength strikes a metal and ejects electrons. The color of light that can eject electrons from a substance is dependent on the substance's work function, the minimum energy necessary to remove an electron from the substance.
Given Cesium's low work function (3.43 × 10^-19 J), it can be activated by a wide range of wavelengths, meaning that all visible colors of light, from red (long wavelength, low energy) to violet (short wavelength, high energy), can eject electrons from it.
However, with Selenium's higher work function (9.5 × 10^-19 J), only light with shorter wavelengths and therefore higher energy, will be able to eject electrons. This means that only light towards the blue/violet end of the spectrum will be able to eject electrons from this element.
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The smallest units of matter that normally CANNOT be broken down are atoms. molecules. cells. phospholipids.
Answer: atoms
Explanation:
All matter is made up of smaller indivisible particles called atoms. These atoms are the smallest units of matter ACCORDING to the Dalton's Atomic theory.
Molecules are combined atoms, while cells and phospholipids are complex combination of atoms.
Therefore, atoms is the answer
The information below refers to six isotopes. How many elements are represented in this group of isotopes?Atomic number Mass number
19 39
6 13
6 12
19 41
82 207
82 206
Answer:
There are 3 elements (6;12) (19;39) and (82;207)
There are 3 isotopes (6;13) (19;41) and (82;206)
Explanation:
Step 1:
Isotopes have the same atomic number but a different mass number
The element with number 19 is Potassium
Potassium has a mass number of 39 g/mol
This is the element potassium and is not an element
41C has mass number of 41 g/mol and is an isotope
The element with number 6 is carbon
Carbon has a mass number of 12 g/mol
13C has a mass number of 13 g/mol and is an isotope
The element with number 82 is lead
Lead has a mass number of 207 g/mol
206Pb has a mass number of 206 g/mol and is an isotope
There are 3 elements (6;12) (19;39) and (82;207)
There are 3 isotopes (6;13) (19;41) and (82;206)
What is the correct numerical setup for calculating the final volume of the helium gas sample?
Answer:
This question is incomplete. But the completed question is below
A sample of helium gas is in a closed system with a movable piston. The volume of the gas sample is changed when both the temperature and the pressure of the sample are increased. Where the initial temperature of the gas is 200K, initial pressure is 2.0 atm, initial volume is 500 mL, the final temperature is 300K and the final pressure of the gas sample is 7.0 atm.
What is the correct numerical setup for calculating the final volume of the helium gas sample?
P₁V₁/T₁ = P₂V₂/T₂ will be used in calculating the final volume.
And the final volume is 214.29 mL
Explanation:
The general gas equation will be used to calculate the final volume. The general gas equation is
P₁V₁/T₁ = P₂V₂/T₂
From the question
P₁ = 2.0 atm
T₁ = 200K
V₁ = 500 mL
P₂ = 7.0 atm
T₂ = 300K
V₂ = unknown
Hence, we have
2 × 500/200 = 7 × V₂/300
V₂ = [tex]\frac{2 * 500 * 300}{200 * 7}[/tex]
V₂ = 214.29 mL
The final volume of He gas sample has been 214.285 mL.
Helium has been assumed to be an ideal gas. The final volume of the gas with an increase in pressure has been given by:
[tex]\dfrac{P_1V_1}{T_1}=\dfrac{P_2V_2}{T_2}[/tex]
Where, the initial pressure of gas, [tex]P_1=2\;\text{atm}[/tex]
The final pressure of gas, [tex]P_2=7\;\text{atm}[/tex]
The initial volume of gas, [tex]V_1=500\;\text{ml}[/tex]
The initial temperature of gas, [tex]T_1=200\;\text K[/tex]
The final temperature of gas, [tex]T_2=300\;\text K[/tex]
Substituting the values for the final temperature of He, [tex]V_2[/tex]:
[tex]\dfrac{2\;\times\;500}{200}=\dfrac{7\;\times\;V_2}{300}\\\\\dfrac{2\;\times\;500}{200}\;\times\;\dfrac{300}{7} = V_2\\\\V_2=214.285\;\rm ml[/tex]
The final volume of He gas has been 214.285 mL.
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What were the learning goals of this lab experiment? Check all that apply.
to use mass and temperature data to do computations involving heat
to demonstrate that different reactions have different enthalpies
to compute a reaction’s enthalpy directly using mass measurements and a calorimeter
to compute the enthalpy of a reaction that cannot be measured directly using a simple calorimeter
Answer:
a abd b
Explanation:
Answer:
all of them
Explanation:
correct on edge
Explain 1 way compounds of binary ionic and binary covalent substances are similar, as well as 2 ways in which they differ.
Answer:
Answer in explanation
Explanation:
The similarity between binary ionic and binary covalent substances is that they both contain only 2 elements each. This means there are two elements in the configuration of both. That is the similarity between them
Now the first difference I will like to mention is the way in which they are bonded. While ionic substances are formed through the transfer of electrons, covalent substances are formed through the sharing of electrons. This means that an element with an excess number of electrons transfer completely a number of electrons to an element that is deficient in electrons. This can be seen in the case of sodium and chlorine. The electron that is transferred is controlled only by the nucleus of the second electron. In the covalent bonding however, the electrons are shared and the electrons shared are controlled by the nuclei of both elements
Another difference is that while binary ionic compounds might dissolve only in polar solvents such as water, binary covalent compounds might only dissolve in non polar solvents such as benzene.
Answer:
Similarity: they involve the presence of both a cation and an anion.
Differences:
1. Electron giving is done in ionic compounds and electrons sharing is done in covalent compounds.
2. Stronger interactions in ionic compounds while weak interactions in covalent compounds.
Explanation:
Hello,
In this case, one similarity present between ionic and covalent compounds is that both of them involve the presence of both a cation and an anion which are positive and negative respectively; this is in order to allow the contituents to gather by bonding either ionically or covalently.
On the flip side, on the difference is that ionic compounds involve the giving of electrons since usually just the anion attain the octet while the covelent compounds allow electron sharing to allow both the cation and the anion to attain the octet.
Nevertheless, despite the electron sharing and giving fact, ionic compounds have stronger interactions bonding the cation and the anion than those covalent compounds have. Ionic interactions are electrostatic and covalent interactions are attractive which are by far weaker than those electrostatic.
Best regards.
Write the molecular and net ionic equations for the reaction in aqueous solution of sulfuric acid with excess lithium hydroxide.
Answer:
[tex]H_2SO_4_{(aq)}+2LiOH_{(aq)}\rightarrow H_2O_{(l)}+Li_2SO_4_{(aq)}[/tex]
[tex]2H^+_{(aq)}+2OH^{-}\rightarrow H_2O_{(l)}[/tex]
Explanation:
Complete ionic equation : In complete ionic equation, all the substance that are strong electrolyte and present in an aqueous are represented in the form of ions.
Net ionic equation : In the net ionic equations, we are not include the spectator ions in the equations.
Only the species which are present in aqueous state dissociate.
Spectator ions : The ions present on reactant and product side which do not participate in a reactions. The same ions present on both the sides.
(a)
The balanced molecular equation will be,
[tex]H_2SO_4_{(aq)}+2LiOH_{(aq)}\rightarrow H_2O_{(l)}+Li_2SO_4_{(aq)}[/tex]
The complete ionic equation in separated aqueous solution will be,
[tex]2H^+_{(aq)}+SO_4^-_{(aq)}+2Li^+_{(aq)}+2OH^{-}_{(aq)}\rightarrow H_2O_{(l)}+2Li^+_{(aq)}+SO_4^-_{(aq)}[/tex]
In this equation the species present are, [tex]Li^+\text{ and }SO_4^-[/tex] are the spectator ions.
Hence, the net ionic equation contains specie is
[tex]2H^+_{(aq)}+2OH^{-}\rightarrow H_2O_{(l)}[/tex]
NaCl(aq) AgNO3(aq) → AgCl(s) NaNO3(aq) : NaCl(aq) AgNO3(aq) \rightarrow AgCl(s) NaNO3(aq) : blank H2SO4(aq) 2 LiOH(aq) → 2 H2O(l) Li2SO4(aq) : H2SO4(aq) 2 LiOH(aq) \rightarrow 2 H2O(l) Li2SO4(aq) : blank HCl(aq) (NH4)2S(aq) → H2S(g) 2 NH4Cl(aq) : HCl(aq) (NH4)2S(aq) \rightarrow H2S(g) 2 NH4Cl(aq) : blank Mg(s) Cu(NO3)2(aq) → Mg(NO3)2(aq) Cu(s) :
The question is incomplete, here is a complete question.
Categorize each reaction into types of chemical reactions.
(1) [tex]NaCl(aq)+AgNO_3(aq)\rightarrow AgCl(s)+NaNO_3(aq)[/tex]
(2) [tex]H_2SO_4(aq)+2LiOH(aq)\rightarrow 2H_2O(l)+Li_2SO_4(aq)[/tex]
(3) [tex]HCl(aq)+(NH_4)_2S(aq)\rightarrow H_2S(g)+2NH_4Cl(aq)[/tex]
(4) [tex]Mg(s)+Cu(NO_3)_2(aq)\rightarrow Mg(NO_3)_2(aq)+Cu(s)[/tex]
Answer :
(1) Precipitation reaction
(2) Neutralization reaction
(3) Double-displacement reaction
(4) Single replacement reaction
Explanation :
(1) The balanced chemical reaction is:
[tex]NaCl(aq)+AgNO_3(aq)\rightarrow AgCl(s)+NaNO_3(aq)[/tex]
This reaction is a precipitation reaction in which an insoluble salt formed when two aqueous solutions are combined. The insoluble salt that settle down in the solution is known an precipitate.
(2) The balanced chemical reaction is:
[tex]H_2SO_4(aq)+2LiOH(aq)\rightarrow 2H_2O(l)+Li_2SO_4(aq)[/tex]
This is a neutralization reaction in which an acid react with a base react to give salt and water as a product that means it reacts to give a neutral solution.
(3) The balanced chemical reaction is:
[tex]HCl(aq)+(NH_4)_2S(aq)\rightarrow H_2S(g)+2NH_4Cl(aq)[/tex]
The given reaction is a double-displacement reaction in which the cation of two reactants molecule exchange their places to give two different products.
(4) The balanced chemical reaction is:
[tex]Mg(s)+Cu(NO_3)_2(aq)\rightarrow Mg(NO_3)_2(aq)+Cu(s)[/tex]
This reaction is a single replacement reaction in which the the more reactive element replace the less reactive element.
The longest wavelength of light with enough energy to break the Cl-Cl bond in Cl2(g) is 495 nm.
1) calculate the frequency in s-1 of the light2) calculate the energy in J of a photon of the light3) calculate the minimun energy in KJ mol-1 of the cl-cl bond
Explanation:
The longest wavelength of light with enough energy to break the Cl-Cl bond = 495 nm = [tex]495\times 10^{-9} m[/tex]
1) The frequency of the light:
[tex]\lambda =495\times 10^{-9} m[/tex]
[tex]\nu=\frac{c}{\lambda }[/tex]
c = speed of light= [tex]3\times 10^8 m/s[/tex]
[tex]\nu=\frac{3\times 10^8 m/s}{495\times 10^{-9} m}[/tex]
[tex]=6.0606\times 10^{14) s^{-1}[/tex]
The frequency of the light is [tex]6.0606\times 10^{14) s^{-1}[/tex].
2)The energy of a photon of the light:
The energy of the photon is given by : E
[tex]E=h\nu [/tex]
h = Planck's constant = [tex]6.626\times 10^{-34} J/s[/tex]
[tex]E=6.626\times 10^{-34} J/s\times 6.0606\times 10^{14) s^{-1}[/tex]
[tex]=4.016\times 10^{-19} J[/tex]
The energy of a photon of the light is [tex]4.016\times 10^{-19} J[/tex].
3) The minimum energy of the Cl-Cl bond :
To break single bond of Cl-Cl bond we need energy E= [tex]4.016\times 10^{-19} J[/tex]
1 mole = [tex]N_A=6.022\times 10^{23} mol^{-1} [/tex]
So, in order to break 1 mole of Cl-Cl bond we will need:
[tex]E\times N_A=4.016\times 10^{-19} J\times 6.022\times 10^{23} mol^{-1} [/tex]
[tex]=241,828.92 J/mol=241,828.92\times 0.001 kJ/mol=241.83 kJ/mol[/tex]
The minimum energy of the Cl-Cl bond is 241.83 kJ/mol.
The frequency of the light radiation has been 6.0606 × [tex]\rm 10^1^4[/tex] /sec. The energy of the light photon has been 4.016 × [tex]\rm 10^-^1^9[/tex] J. The minimum energy in the Cl-Cl bond has been 241.8292 kJ/mol.
(1) The frequency can be defined as the number of times the wave has been repeated, while the wavelength has been defined as the distance of one wave.
The frequency of the wave in the air can be given as:
Frequency = [tex]\rm \dfrac{speed}{wavelength}[/tex]
Frequency of 495 nm wavelength has been :
Frequency = [tex]\rm \dfrac{3\;\times\;10^8\;m/sec}{495\;\times\;10^-^9\;m}[/tex]
Frequency = 6.0606 × [tex]\rm 10^1^4[/tex] /sec
The frequency of the light radiation has been 6.0606 × [tex]\rm 10^1^4[/tex] /sec.
(2) The energy of the light photon has been given by:
Energy = Plank's constant × Frequency
Energy = 6.626 × [tex]\rm 10^-^3^4[/tex] J/s × 6.0606 × [tex]\rm 10^1^4[/tex] /sec
The energy of the photon = 4.016 × [tex]\rm 10^-^1^9[/tex] J.
The energy of the light photon has been 4.016 × [tex]\rm 10^-^1^9[/tex] J.
(3) The minimum energy of Cl-Cl bond has been given by:
The energy for 1 photon = 4.016 × [tex]\rm 10^-^1^9[/tex] J.
The energy for 1 mole of Cl-Cl has been the minimum energy for breaking Cl-Cl bond.
1 mole = 6.023 × [tex]\rm 10^2^3[/tex] atoms
Energy for Cl-Cl bond has been = 4.016 × [tex]\rm 10^-^1^9[/tex] J × 6.023 × [tex]\rm 10^2^3[/tex] atoms
Energy for Cl-Cl bond has been = 241,828.92 J/mol
Energy for Cl-Cl bond has been = 241.8292 kJ/mol.
The minimum energy in the Cl-Cl bond has been 241.8292 kJ/mol.
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What is the melting point of a 3L aqueous solution that contains 100g of MgCl2? kf H2O=1.86 rhoH2O=1gmL
Answer:
Melting point of aqueous solution = -10.32 °C
Explanation:
[tex]\Delta T_f=i \times k_f \times m[/tex]
Where,
ΔT_f = Depression in freezing point
k_f = molal depression constant
m = molality
Formula for the calculation of molality is as follows:
[tex]m=\frac{Mass\ of\ solute\ (kg)}{molecular\ mass\ of\ solute \times mass\ of\ solvent}[/tex]
density of water = 1 g/mL
density = mass/volume
Therefore,
mass = density × volume
volume = 3 L = 3000 mL
Mass of water = 1 g/mL × 3000 mL
= 3000 g
[tex]Molality(m)=\frac{100\times1000}{18\times 3000} \\=1.85\ m[/tex]
van't Hoff factor (i) for MgCl2 = 3
Substitute the values in the equation (1) to calculate depression in freezing point as follows:
[tex]\Delta T_f=i \times k_f \times m\\=3\times 1.86 \times 1.85\\=10.32\ °C[/tex]
Melting point of aqueous solution = 0 °C - 10.32 °C
= -10.32 °C
Answer:
The melting point of the solution is - 1.953 °C
Explanation:
In an ideal solution, the freezing point depression is computed as follows:
[tex]ΔT_f = k_f \times b \times i [/tex]
where:
[tex]ΔT_f[/tex] is the freezing-point depression
[tex]k_f[/tex] is the cryoscopic constant, in this case is equal to 1.86
b is the molality of the solution
i is the van't Hoff factor, number of ion particles per individual molecule of solute, in this case is equal to 3
Molality is defined as follows:
b = moles of solute/kg of solvent
Moles of solute is calculated as follows:
moles of solute = mass of solute/molecular weight of solute
In this case there are 100 g of solute and its molecular weight is 35.5*2 + 24 = 95 g/mole. So, the moles are:
moles of solute = 100 g/(95 g/mol) = 1.05 moles
The mass of solvent is computed as follows:
mass of solvent = density of solvent * Volume of solvent
Replacing with the data of the problem we get:
mass of solvent = 1 kg/L*3 L = 3 kg
Finally, the molality of the solution is:
b = 1.05/3 = 0.35 mol/kg
Then, the freezing-point depression is:
[tex]ΔT_f = 1.86 \times 0.35 \times 3 [/tex]
[tex]ΔT_f = 1.953 C[/tex]
The freezing-point depression is the difference between the melting point of the pure solvent (here water) and the melting point of the solution. We know that the the melting point of water is 0 °C, then:
melting point of water - melting point of the solution = 1.953 °C
melting point of the solution = 0 °C - 1.953 °C = - 1.953 °C
Choose the following statements that show evidence for a chemical reaction.
1. Dropping sodium metal into water produces fizzing
2. Dissolving a white powder in solution gives white light
3. Mixing two aqueous solutions produces a precipitate
4. Mixing two 10.0 mL solutions gives a volume of 19.5 mL
Explanation:
A chemical reaction is defined as the reaction in which bonds between the reactants either break or form which leads to the formation of a new substance.
For example, [tex]2Li + Cl_{2} \rightarrow 2LiCl[/tex]
So, when we drop a sodium metal into water then it produces a frizzing sound which shows the metal is reacting with water.
We know that when two aqueous solutions chemically react with each other then it may lead to the formation of an insoluble substance which is known as precipitate.
This means that formation of a precipitate is also a chemical reaction.
Thus, we can conclude that following are the statements which show evidence for a chemical reaction.
Dropping sodium metal into water produces fizzing.Mixing two aqueous solutions produces a precipitate.The hormone that directly controls water reabsorption by the kidneys is
Answer:
It is called an antidiurectic hormone
The spontaneous reaction that occurs when the cell in the picture operates is as follows: 2Ag+ + Cd(s) ???? 2 Ag(s) + Cd2+ (A) Voltage increases. (B) Voltage decreases but remains > zero. (C) Voltage becomes zero and remains at zero. (D) No change in voltage occurs. (E) Direction of voltage change cannot be predicted without additional information. Which of the above occurs for each of the following circumstances? 14. A 50-milliliter sample of a 2-molar Cd(NO3)2 solution is added to the left beaker. 15. The silver electrode is made larger. 16. The salt bridge is replaced by a platinum wire. 17. Current is allowed to flow for 5 minutes.
Answer:
14. B 15. D 16. C 17. B
Explanation:
The spontaneous reaction that occurs when the cell operates is shown below:
[tex]2Ag^{+} + Cd_{(s)}[/tex] ⇒[tex]2Ag_{(s)} + Cd^{2+}[/tex]
We need to select the correct option from the list below for the following questions.
(A) Voltage increases. (B) Voltage decreases but remains > zero. (C) Voltage becomes zero and remains at zero. (D) No change in voltage occurs. (E) Direction of voltage change cannot be predicted without additional information.
14. A 50-milliliter sample of a 2-molar [tex]Cd(NO_{3})_{2}[/tex] solution is added to the left beaker.
If a 50-milliliter sample of a 2-molar [tex]Cd(NO_{3})_{2}[/tex] solution is added to the left beaker, the voltage decreases but its value remains greater than zero. The correct option is B
15. The silver electrode is made larger.
If the silver electrode is made larger, no change in the value of the voltage since we don't have the idea of the initial value. The correct option is D.
16. The salt bridge is replaced by a platinum wire.
If the salt bridge is replaced by a platinum wire, there will be no passage of electrons because electrons can't pass through a platinum wire. Therefore, the voltage will be zero and remains at zero. The correct option is C.
17. Current is allowed to flow for 5 minutes.
If current is allowed to flow for 5 minutes, the voltage decreases but its value remains greater than zero. The correct option is B.
A galvanic cell produces energy by a spontaneous redox reaction.
In galvanic or voltaic cell, energy is produced via a spontaneous redox reaction. The redox reaction equation of this reaction is; 2Ag^+ + Cd(s) ---> 2 Ag(s) + Cd^2+.
The answers to the questions are as follows;
14) When we add 50-milliliter sample of a 2-molar solution of cadmium nitrate, the voltage will decrease but remains greater than zero.
15) The voltage will remain the same after the increase in the size of the silver electrode because its initial value is unknown.
16) The voltage will remain at zero if the salt bridge is replaced by a platinum wire since current can not pass through
17) The voltage will decrease if current flows for five minutes.
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Trenton collects a sample of moist air. One of these factors is unrelated to the amount water vapor in his sample. Which factor is it? A. Pressure B. Temperature C. Vapor density D. Volume E. Wind speed
Wind speed is unrelated to the amount of water vapour in the sample of moist air.
Answer: Option E
Explanation:
As the sample of moist air is combination of water vapour mixed with air molecules, there will be no generation of wind in the moist air. But there will be change in the pressure and temperature when water vapours or moisture mixes with air molecules.
As water is having high density compared to air molecules, the pressure will be changed in moist air. So, the amount of water vapour in the moist air sample can measure by relative difference in pressure, temperature, vapour density and volume with air molecules in general.
Answer:
Answer E
Explanation:
A 15.85g piece of iron absorbs 1086.75 joules of heat energy and its temperature changes from 25 degrees Celsius to 175 degrees celcius. Calculate the specific heat capacity of iron.
Answer:
Explanation:
Specific heat capacity of iron is the amount of heat required to raise 1g of iron by 1 degree Celsius.
The formula is Q=mc∆T
Where Q is energy in joules.
M is mass in gram.
C is specific heat capacity in J/g°C.
∆T is change in temperature in degree Celsius
Q=1086.75joules
M=15.85g
C=?
∆T = final T-initial T(175-25)=150°c.
Q=Mc∆T
1086.75= 15.85×C×150
1086.85=2377.5c
C=1086.85÷2377.5
C=0.46J/g°C.
Hydrogen is unique among the elements because ________. 1. It is not really a member of any particular group. 2. Its electron is not at all shielded from its nucleus. 3. It is the lightest element. 4. It is the only element to exist at room temperature as a diatomic gas. 5. It exhibits some chemical properties similar to those of groups 1A and 7A.
Hydrogen is unique due to several factors: it doesn't belong definitively to any group, its electron is unshielded from its nucleus, it is the lightest element, it exists as a diatomic gas at room temperature, and it exhibits properties of both alkali metals and halogens.
Explanation:Hydrogen is indeed unique among the elements for several reasons. Firstly, it is not really a member of any particular group on the periodic table. It is often placed with Group 1A (the alkali metals) because it has one electron in its outer shell like them, but it also exhibits properties similar to Group 7A (the halogens), as it needs one more electron to complete its shell. Secondly, its electron is not at all shielded from its nucleus, resulting in an unusual level of interaction between the two. Thirdly, hydrogen is the lightest element, which impacts its physical and chemical properties. Fourthly, it is the only element to exist at room temperature as a diatomic gas; in its natural state, hydrogen gas (H2) is made up of two hydrogen atoms bonded together. Finally, as already mentioned, it shares chemical properties with both alkali metals and halogens.
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What volume of a 0.22 m silver nitrate solution is required to precipitate all the cl− ion in the solution as agcl?
To calculate the volume of silver nitrate solution required to precipitate all the Cl- ions as AgCl, use the concentration of Cl- ions in the solution and the stoichiometric ratio between Ag+ and Cl- ions. The volume of solution is equal to the volume of the silver nitrate solution.
Explanation:To calculate the volume of a 0.22 M silver nitrate solution required to precipitate all the Cl- ions as AgCl, we need to determine the stoichiometric ratio between Ag+ and Cl- ions in the reaction. Since the balanced equation is Ag+ + Cl- → AgCl, the ratio is 1:1. We can use the concentration of Cl- ions in the solution to determine the volume of the silver nitrate solution needed.
The concentration of Cl- ions in the solution is reduced to half its initial value when AgNO3 and NaCl solutions are mixed. Given a concentration of 2.0 × 10^-4 M, after mixing, it becomes 1.0 × 10^-4 M. To calculate the volume of silver nitrate solution required, we can use the following equation:
Volume (L) = moles of Cl-/concentration of Cl-
Let's assume the volume of silver nitrate solution required is V liters: V = (moles of Cl-) / (1.0 × 10^-4 M)
To determine the moles of Cl-, we can use the equation:
moles of Cl- = concentration of Cl- × volume of solution (in liters)
Substituting the given concentration and volume:
moles of Cl- = 1.0 × 10^-4 M × V
Now, substituting the value of moles of Cl- in the volume equation:
V = (1.0 × 10^-4 M × V) / (1.0 × 10^-4 M)
This simplifies to V = V, meaning the volume of silver nitrate solution required to precipitate all the Cl- ions is equal to the volume of the solution.
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To precipitate all the Cl- ions in a 0.22 M silver nitrate solution as AgCl, an equal volume of the solution is required.
Explanation:In order to determine the volume of a 0.22 M silver nitrate solution required to precipitate all the Cl- ions as AgCl, we can use stoichiometry. The equation for the reaction is:
Ag+ + Cl- → AgCl
From the balanced equation, we can see that 1 mole of AgCl is formed for every 1 mole of Cl- ions. Given the concentration of the silver nitrate solution, we can use the equation M1V1 = M2V2 to solve for the volume of the solution required.
Let V be the volume of the silver nitrate solution. Using the equation M1V1 = M2V2:
(0.22 M)(V) = (0.22 M)(V/2)
Simplifying the equation, we get:
V = V/2
Therefore, in order to precipitate all the Cl- ions, you would need to use an equal volume of the silver nitrate solution.
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What is the difference between a renewable and nonrenewable resource
Answer:
Answer in explanation
Explanation:
A renewable source of energy is an energy source that cannot be depleted. It is an energy source with constant abundance and hence it is always in abundance. What we are saying is that they are energy sources that cannot be used up. Although it might sometimes be that it is unavailable at some instances, this does not take away the fact that it is abundant and cannot be depleted, although the strength at different times may vary. Example of renewable energy sources include solar energy, wind energy, hydroelectric power source etc. These sources are never depleted and are in abundance.
Non renewable source of energy are those sources of energy that can be depleted. A good example of this can be seen in fossil fuels. Fossil fuels are usually burned to produce energy. They are used up in the process and it will require an additional amount of fossil fuel to be restocked for the energy to be continually supplied.
Explanation: Renewable resources can be replenished whenever you want, but non-renewable resources will keep dwindling down till there's nothing. For example, solar power is a renewable resource and will always be there because the sun will keep providing more solar power. Coal, on the other hand, is a non-renewable resource and won't always be there because coal takes a lot longer (300 million years) to form.
Lithium ion salts were originally found in Seven-Up® drinks. How many electrons does Li atom lose to become an ion?
Answer: One (1) electron
Explanation:
Lithium is a group 1 element with an atomic number of 3. Thus, it has just 3 electrons and its electronic configuration is 1s2, 2s1
To become lithium ion salts, it gives off its lone electron thereby becoming Li+ with configuration of 1s2 with just 2 electrons left.
So, Li atom loses only ONE ELECTRON to become an ion
Apply solubility rules of inorganic slats to predict the occurance of precipitation reactions?
Explanation:
An ionic solution is when a compound's ions in an aqueous solution have dissociated. As you combine two aqueous solutions, a reaction occurs. This is when you find out whether or not a precipitate is going to form. A precipitate occurs when the ion reaction component in water is insoluble.The formation of a precipitate is an indication that a chemical change has occurred. for example if we mix clear solutions of silver nitrate and sodium chloride, sodium nitrate is formed which is a precipitate.
Zeke is on spring break. He lives in a cold climate, so he decides to drive to a warmer climate. Before he leaves for his vacation, he checks the air pressure in his tires. After a few days of driving, he reaches his destination and stops for more fuel. While fueling up, he checks his tires' air pressure again and notices it has increased.
Which option best explains the change in the air pressure of Zeke's tires? Select all that apply.
a. The warmer temperatures at Zeke's destination caused the volume of air in his tires to decrease.
b. The warmer temperatures at Zeke's destination caused the volume of air in his tires to increase.
c. The warmer temperatures at Zeke's destination caused the pressure in his tires to spread out equally.
d. The warmer temperatures at Zeke's destination caused the pressure in his tires to increase.
Answer:
The answers are
The warmer temperatures at Zeke's destination caused the pressure in his tires to increase.
The warmer temperatures at Zeke's destination caused the pressure in his tires to increase.
The warmer temperatures at Zeke's destination caused the pressure in his tires to spread out equally.
Explanation:
A sample of gas contains four gases (He, Ne, Ar, and Xe) with the following partial pressures: He (43 mm Hg), Ar (835 mm Hg), and Xe (111 mm Hg). If the total pressure in the container is 1355 mm Hg, what is the partial pressure of Ne in the sample?
To find the partial pressure of Ne in the sample, subtract the sum of the partial pressures of the other gases from the total pressure.
Explanation:To find the partial pressure of Ne in the sample, we need to first determine the partial pressures of all the gases in the mixture. The total pressure in the container is 1355 mm Hg. The partial pressures given are: He (43 mm Hg), Ar (835 mm Hg), and Xe (111 mm Hg).
To find the partial pressure of Ne, we need to subtract the sum of the partial pressures of the other gases from the total pressure.
Partial pressure of Ne = Total pressure - (Partial pressure of He + Partial pressure of Ar + Partial pressure of Xe).
What is catalysis and what does a catalyst do to the activation energy of a reaction, and to the rate of the reaction. Does a catalyst change the nature of the products of the reaction? If a reaction is in equilibrium, does adding a catalyst shift the equilibrium?
Answer:
Answer in explanation
Explanation:
A catalyst is a substance that alter the rate of a chemical reaction. It either speeds up the rate of the chemical reaction or slows down the rate of the chemical reaction. Hence, we say a catalyst can either work positively or negatively.
A catalyst will bring down the value of the activation energy. It reduces the minimum amount of energy needed for the reaction to kickstart. Hence we say it tends to create an alternative pathway for the chemical reaction to proceed.
When it speeds up the rate, it is otherwise known as a positive catalyst, otherwise it is a negative catalyst.
A catalyst does not have any business with the nature of the products or the reactants. Its work is simple, either hasten or slow down the rate of a chemical reaction.
A catalyst has no effect On the equilibrium position of a chemical reaction. This is to say its addition or subtraction has no effect on the position of a chemical reaction
Catalysis is the process by which a catalyst lowers the activation energy of a chemical reaction, thus increasing the reaction rate without changing the nature of the products. A catalyst does not shift the position of a reaction at equilibrium but enables the system to reach equilibrium more quickly.
Explanation:What is Catalysis?
Catalysis refers to the process by which a catalyst increases the rate at which a chemical reaction occurs. A catalyst facilitates a chemical reaction without undergoing any permanent chemical change itself. It works by providing an alternative reaction pathway with a lower activation energy (Ea), which is the energy required to initiate the reaction. This lower activation energy means that more reactant molecules can effectively collide and react at a given temperature, thereby speeding up the reaction rate.
Effect on Activation Energy and Reaction Rate
The presence of a catalyst in a chemical reaction results in a lower activation energy barrier. This, in turn, means that a greater percentage of reactant molecules have enough energy to overcome this barrier and form products. Consequently, the reaction rate is increased since the reaction can proceed faster.
Does a Catalyst Change the Nature of the Products?
A catalyst does not affect the energy of the reactants or the products, nor does it alter the overall thermodynamics of the reaction. Therefore, it does not change the nature of the products of the reaction.
Adding a Catalyst to a Reaction in Equilibrium
When a reaction is in equilibrium, adding a catalyst will not shift the equilibrium position or alter the concentrations of reactants and products at equilibrium. Instead, it will increase the rate at which equilibrium is reached by speeding up both the forward and reverse reactions equally.
Predict the sign of ΔSsys for each process. Which are positive? A. A pond freezes in winter. B. Atmospheric CO2 dissolves in the ocean. C. An apple tree bears fruit. D. None of them are positive. Which are negative? A. A pond freezes in winter. B. Atmospheric CO2 dissolves in the ocean. C. An apple tree bears fruit. D. None of them are negative.
Answer:
Which are positive? D.
Which are negative? A. B. C.
Explanation:
Generally, entropy can be defined as the degree of randomness of a system. The entropy of any system increases with an increase in the number of moles of the system. Entropy also increases when there is a change of state from solid to liquid or liquid to gas. Therefore for the systems in the given question:
A pond freezes in winter
The degree of disorderliness decrease because there is a change of state from liquid to solid. Thus, ΔSsys is negative.
Atmospheric CO2 dissolves in the ocean
There is also decrease in randomness, thus, ΔSsys is negative.
An apple tree bears fruit
There is also decrease in randomness, thus, ΔSsys is negative.
A pond freezes in winter, atmospheric CO2 dissolves in the ocean, and an apple tree bears fruit are negative changes in Delta S.
What is Delta S?Delta S is a measurement used in thermodynamics to calculate the modifications in the level of entropy.
The term entropy makes reference to the degree of randomness (disorder) of a thermodynamic system. A negative delta S involves a decrease in entropy (disorder) regarding a particular system.In conclusion, a pond freezes in winter, atmospheric CO2 dissolves in the ocean, and an apple tree bears fruit are negative changes in Delta S.
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According to this decay series chart, which is the proper order of nuclear particle emission that occurs during the transition from lead-214 to lLead-210?
A) Lead-214 changes to bismuth-214.
B) Bismuth-214 changes to polonium-214.
C) Polonium-214 changes to lead-210.
Explanation:
An alpha particles is basically a helium nucleus and it contains 2 protons and 2 neutrons.
Symbol of an alpha particle is [tex]^{4}_{2}\alpha[/tex].
A beta particle is a particle with a negatively charged electron. Symbol of a beta particle is [tex]^{0}_{-1}\beta[/tex].
According to the given question, the decay series chart along with reaction equation are as follows.
(a) Lead-214 changes to bismuth-214.
[tex]^{214}_{82}Pb \rightarrow ^{214}_{83}Bi + ^{0}_{-1}e[/tex]
(b) Bismuth-214 changes to polonium-214.
[tex]^{214}_{83}Bi \rightarrow ^{214}_{84}Po + ^{0}_{-1}e[/tex]
(c) Polonium-214 changes to lead-210.
[tex]^{214}_{84}Po \rightarrow ^{210}_{82} + ^{4}_{2}He[/tex]
Therefore, we can conclude that proper order of nuclear particle emission is beta, beta, alpha.