Explanation:
Molar mass of C2H6= 2×12+6=30
30 g of C2H6 gives 1 mol of C2H6
10.0 g of C2H6 gives 1/30 ×10= 1/3 mol of C2H6
1 mol of C2H6 has 2 mol of Carbon
1/3 mol of C2H6 has 1/3 ×2 = 2/3 Molly of Carbon.
No. of atoms = 2/3× 6.023×10^23
=4.01×10^23
To determine the number of carbon atoms in 10.0 g of C2H6, calculate the number of moles from the mass and molar mass, and then multiply by Avogadro's number and the number of carbon atoms per molecule of ethane. This results in approximately 4.015 × 1023 carbon atoms.
Explanation:To find out how many carbon atoms are in 10.0g of C2H6, we first need to calculate the molar mass of ethane (C2H6). The molar mass is the sum of the masses of all the atoms in a molecule. Carbon has a molar mass of approximately 12 g/mol, and hydrogen has a molar mass of about 1 g/mol. Therefore, the molar mass of C2H6 is (2 × 12 g/mol) + (6 × 1 g/mol) = 30 g/mol.
Next, we calculate how many moles of C2H6 are in 10.0 g of the substance using the molar mass:
Number of moles of C2H6 = mass ÷ molar mass = 10.0 g ÷ 30 g/mol
This gives us approximately 0.333 moles of C2H6. Since each molecule of ethane contains 2 carbon atoms, we can find the total number of carbon atoms:
Total number of carbon atoms = number of moles of C2H6 × Avogadro's number × number of carbon atoms per molecule = 0.333 moles × 6.022 × 1023 atoms/mol × 2
Finally, this calculation will give us the total number of carbon atoms in 10.0 g of C2H6, which is approximately 4.015 × 1023 carbon atoms.
How do you know when a chemical reaction has occurred
Answer:
The Substance Has Changed and Has Become Something Else
Explanation:
When a chemical reaction occurs it has a few characteristics, for example burning. The substance, paper, becomes something else, ash. The ash can no longer be turned back into paper. Another example is rust, once and object is rust due to oxidation it can no longer return back. A physical reaction on the other hand can be reversed, like freezing. To spot chemical change look for color changing, gas production, a change in temperature, or if you see any light.
Which isomers can have different physical or chemical properties?
structural isomers only
geometric isomers only
both structural isomers and geometric isomers
neither structural isomers nor geometric isomers
Explanation:
isomers Chemical compounds having the same molecular formula but different properties due to the different arrangement of atoms within the molecules. Structural isomers haveatoms connected in different ways. Geometric isomers, also called cis-trans isomers, differ in their symmetry about a double bond.
Answer: Option (b) is the correct answer.
Explanation:
A geometric isomer is defined as an isomer that contains different arrangement of groups across the double bond, ring etc. Generally, coordination compounds show geometric isomers.
For example, cis-2,butene and trans-2,butene are geometrical isomers.
Geometrical isomers cause change in geometry of a compound. Due to this both physical and chemical properties of a substance changes.
On the other hand, structural isomers are the isomers that have same chemical formula but different structure due to different sequence of atoms present in the formula.
For example, butane and isobutane are structural isomers.
Therefore, we can conclude that geometric isomers only have different physical or chemical properties. ty
Write an experiment to show that air exerts pressure in all directions
Answer:
Experiment: Submit a can or plastic bottle with hot, sealed air to a sudden cooling and watch what happens.Explanation:
Air is a mixture of gases (mainly oxygen and nitrogen, but also carbon dioxide, water vapor, and others in minimum amount).
The pressure of the gases is the product of the collisions of the air molecules with the surface of the objects. Since the molecules of gases are in constant, rapid random motion, they are constantly (you may say continously) colliding with the surfaces of the objects in all directions. That explain, why the air exertes pressure in all directions.
There are many experiments that you can perform to show this phenomenum.
You can perform this experiment, for example:
Take an "empty" can or plastic bottle, which you can heat using a source of hot water. You can do this by introducing the can or plastic bottle inside a pan with hot water, avoiding that the water enters into the your object.Once the air inside the can or plastic bottle is hot, remove it from the pan and close it, so that air cannot exit from of enter into it.Pour cold water over the can or plastic.What will you observe?
The can or plastic bottle will collapse.Why does that happen?
Because, when you pour cold water over the can or plastic bottle the air inside will cool down, and as result the air inside it will exert less pressure over the inner walls than the pressure that the air ouside it exerts over the outer walls.Since the pressure is exerted in all the directions, the bottle or can collapse.
Initially a beaker contains 225.0 mL of a 0.350 M MgSO4 solution. Then 175.0 mL of water are added to the beaker. Find the concentration of the final solution
Answer:
came
Explanation:
Answer:
400.0
Explanation:
I just got it right
The kw for water at 0 °c is 0.12× 10–14 m2. Calculate the ph of a neutral aqueous solution at 0 °c.
Answer:
pH = 7.46.
Explanation:
The ionization of water is given by the equation :H₂O(l) ⇄ H⁺(aq) + OH⁻(aq),
The equilibrium constant (Kw) expression is:
Kw = [H⁺][OH⁻] = 0.12 x 10⁻¹⁴.
in pure water and neutral aqueous solution, [H⁺] = [OH⁻]
So, Kw = [H⁺]²
∴ 0.12 x 10⁻¹⁴ = [H⁺]²
∴ [H⁺] = 3.4 x 10⁻⁸ M.
∵ pH = - log [H⁺]
pH = - log (3.4 x 10⁻⁸) = 7.46.
Use the standard enthalpies of formation for the reactants and products to solve for the ΔHrxn for the following reaction. (The ΔHf of C2H4 is 52.26 kJ/mol, CO2 is -393.509 kJ/mol, and H2O is -241.818 kJ.) C2H4 (g) + 3O2(g) 2CO2 (g) + 2H2O(g)
ΔHrxn =
The reaction is .
Answer: The enthalpy change of the reaction is -1322.91 kJ
Explanation:
The chemical equation for the combustion of propane follows:
[tex]C_2H_4(g)+3O_2(g)\rightarrow 2CO_2(g)+2H_2O(g)[/tex]
The equation for the enthalpy change of the above reaction is:
[tex]\Delta H^o_{rxn}=[(2\times \Delta H^o_f_{(CO_2(g))})+(2\times \Delta H^o_f_{(H_2O(g))})]-[(1\times \Delta H^o_f_{(C_2H_4(g))})+(3\times \Delta H^o_f_{(O_2(g))})][/tex]
We are given:
[tex]\Delta H^o_f_{(H_2O(g))}=-241.818kJ/mol\\\Delta H^o_f_{(O_2(g))}=0kJ/mol\\\Delta H^o_f_{(CO_2(g))}=-393.509kJ/mol\\\Delta H^o_f_{(C_2H_4(g))}=52.26kJ/mol[/tex]
Putting values in above equation, we get:
[tex]\Delta H^o_{rxn}=[(2\times (-393.509))+(2\times (-241.818))]-[(1\times (52.26))+(3\times (0))]\\\\\Delta H^o_{rxn}=-1322.91kJ[/tex]
Hence, the enthalpy change of the reaction is -1322.91 kJ
In what kind of reaction do two or more substances combine to form a new compound
Answer:
Combination or synthesis
Explanation:
In combination or synthesis, there is formation of a single product from two or more reactants e.g:
H₂ + I₂ → 2HI
Here a compound forms from the association of the consituent elements.
Other kinds of chemical reactions we have are:
Decomposition or crackingSingle replacement or single displacementDouble replacement or double decomposition or metathesis.In a conductivity apparatus, like the one above, you should never touch the ___ while the power is on. A Light Bulb B Leads C Wires D Base of the battery
Answer:
Leads
Explanation:
In the conductivity apparatus, you should never touch Leads while the power is on. Hence, option B is correct.
What is leads?Lead (Pb) is a metal.
If a person touches a live conductor, a current may flow through the body to the ground and cause a shock.
That's why in the conductivity apparatus, you should never touch Leads while the power is on.
Hence, option B is correct.
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How does carbon move from living things to the atmosphere
Answer:
Each time you exhale, you are releasing carbon dioxide into the atmosphere. Animals and plants get rid of carbon dioxide gas through a process called respiration. Carbon moves from fossil fuels to the atmosphere when fuels are burned.
Answer:
Animals and plants need to get rid of carbon dioxide gas through a process called respiration. Carbon moves from fossil fuels to the atmosphere when fuels are burned. When humans burn fossil fuels to power factories, power plants, cars and trucks, most of the carbon quickly enters the atmosphere as carbon dioxide gas.
Explanation:
Carbon moves from living things to the atmosphere. Each time you exhale, you are releasing carbon dioxide gas (CO2) into the atmosphere. Animals and plants need to get rid of carbon dioxide gas through a process called respiration. Carbon moves from fossil fuels to the atmosphere when fuels are burned.
Which activity describes an application of topographic maps? Check all that apply.
recreation, such as camping and hiking
engineering, such as the construction of roads and buildings
science, such as mapping stars in the sky
business, such as analyzing population centers
science, such as analyzing surface features
Answer:
Option (1), (2) and (5)
Explanation:
Topographic maps are those that illustrate the surface features of different areas. It provides detailed information about an area such as the relief, hills, basins, rivers, and mountains and is constructed in both small and large scale. These maps are often used by geographers and geologists to study about any particular area.
In the given question, these topographic maps are used for recreation purposes including camping, hiking that enables them to lead the path. It is also used by the engineering geologist and engineers for the construction of roads and railways, buildings and houses, as the more resistant and reliable surfaces are traced out and used for these purposes. And mostly used by the geologists in order to understand how these surface features like folds, faults, mountains, and valleys have formed and evolved with the increasing time.
Hence the correct answers are option (1), (2) and (5)
Answer:
1,2 and 5
Explanation:
Consider a sample of 10.0 g of the gaseous hydrocarbon C2H6 to answer the following question: How many moles are present in this sample?
When answering the question, include the following:
State how to find the molar mass for the hydrocarbon.
State how you know if you need to multiply or divide by the molar mass.
Give the correct number of significant figures and explain why the answer has that many significant figures.
Answer: The moles of given hydrocarbon is 0.3 moles
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
We are given:
Given mass of ethane = 10.0 g
Molar mass of ethane = [tex][(2\times 12)+(6\times 1)]=30g/mol[/tex]
We need to divide the given value by the molar mass.
Putting values in above equation, we get:
[tex]\text{Moles of ethane}=\frac{10.0g}{30g/mol}=0.3mol[/tex]
In case of multiplication and division, the number of significant digits is taken from the value which has least precise significant digits. Here, the least precise number of significant digits are 1.
Hence, the moles of given hydrocarbon is 0.3 moles
Final answer:
To find the number of moles of C₂H₆ in a 10.0 g sample, calculate the molar mass (30.0 g/mol) and divide the sample mass by the molar mass, resulting in approximately 0.333 moles. The answer has three significant figures, aligning with the initial mass provided.
Explanation:
To find the number of moles in a 10.0 g sample of C₂H₆, first, calculate the molar mass of C₂H₆. The molar mass is found by summing the atomic masses of all atoms in the molecule, which are 2 atoms of Carbon (C) and 6 atoms of Hydrogen (H). The atomic mass of Carbon is 12.0 g/mol and that of Hydrogen is 1.0 g/mol, resulting in a molar mass of 30.0 g/mol for C₂H₆.
To find the number of moles, you divide the mass of the sample by the molar mass of the compound. Therefore, divide 10.0 g by 30.0 g/mol, which equals approximately 0.333 moles of C₂H₆.
The answer, 0.333 moles, has three significant figures because the provided mass (10.0 g) has three significant digits. This is in accordance with the rule that the result of a division or multiplication operation in chemistry should have the same number of significant figures as the operand with the least number of significant figures.
If a liquid is sealed in a container and kept at constant temperature, how does its vapor pressure change over time?
It continues to steadily increase.
It increases at first, then remains constant.
It increases at first, then decreases.
It continues to steadily decrease.
Answer:
C. it will increase at first, then remain constant
Explanation:
1) In saturated limewater, [H+ ]=3.98x10-13 M.
a) Find [OH]-/
b) What is the pH?/
c) Is the solution acidic, basic, or neutral?/
2) In butter, [H+ ]=6.0x10-7 M.
a) Find [OH]-/
b) What is the pH?/
c) Is the solution acidic, basic, or neutral?/
3) In peaches, [OH]=3.16x10-11 M
a) Find [H+ ]/
b) What is the pH?/
c) Is the solution acidic, basic, or neutral?/
4) During the course of the day, human saliva varies between being acidic and basic. If [OH]=3.16x10-8 M,
a) Find [H+ ]/
b) What is the pH?/
c) Is the solution acidic, basic, or neutral?/
Answer:
1) a) [OH⁻] = 0.025 M.
b) pH = 12.4.
c) The solution is basic.
2) a) [OH⁻] = 1.66 x 10⁻⁸ M.
b) pH = 6.22.
c) The solution is acidic.
3) a) [H⁺] = 3.16 x 10⁻⁴ M.
b) pH = 3.5.
c) The solution is acidic.
4) a) [H⁺] = 3.16 x 10⁻⁷ M.
b) pH = 6.5.
c) The solution is acidic.
Explanation:
1) In saturated lime water, [H⁺] = 3.98 x 10⁻¹³ M.
a) Find [OH⁻]
∵ [H⁺][OH⁻] = 10⁻¹⁴.
∴ [OH⁻] = 10⁻¹⁴/[H⁺] = 10⁻¹⁴/(3.98 x 10⁻¹³ M) = 0.025 M.
b) What is the pH?
∵ pH = - log[H⁺].
[H⁺] = 3.98 x 10⁻¹³ M.
∴ pH = - log(3.98 x 10⁻¹³ M) = 12.4.
c) Is the solution acidic, basic, or neutral?
We can determine the nature of the solution, acidic, basic or neutral, from the value of the pH.pH is a scale from 0 to 14.
If pH < 7, the solution is acidic.If pH = 7, the solution is neutral.If pH > 7, the solution basic.∵ pH = 12.4 > 7.
∴ The solution is basic.
2) In butter, [H⁺] = 6.0 x 10⁻⁷ M.
a) Find [OH⁻]
∵ [H⁺][OH⁻] = 10⁻¹⁴.
∴ [OH⁻] = 10⁻¹⁴/[H⁺] = 10⁻¹⁴/(6.0 x 10⁻⁷ M) = 1.66 x 10⁻⁸ M.
b) What is the pH?
∵ pH = - log[H⁺].
[H⁺] = 6.0 x 10⁻⁷ M.
∴ pH = - log(6.0 x 10⁻⁷ M) = 6.22.
c) Is the solution acidic, basic, or neutral?
We can determine the nature of the solution, acidic, basic or neutral, from the value of the pH.pH is a scale from 0 to 14.
If pH < 7, the solution is acidic.If pH = 7, the solution is neutral.If pH > 7, the solution basic.∵ pH = 6.22 < 7.
∴ The solution is acidic.
3) In peaches, [OH⁻] = 3.16 x 10⁻¹¹ M
a) Find [H⁺]
∵ [H⁺][OH⁻] = 10⁻¹⁴.
∴ [H⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(3.16 x 10⁻¹¹ M) = 3.16 x 10⁻⁴ M.
b) What is the pH?
∵ pH = - log[H⁺].
[H⁺] = 3.16 x 10⁻⁴ M.
∴ pH = - log(3.16 x 10⁻⁴ M) = 3.5.
c) Is the solution acidic, basic, or neutral?
We can determine the nature of the solution, acidic, basic or neutral, from the value of the pH.pH is a scale from 0 to 14.
If pH < 7, the solution is acidic.If pH = 7, the solution is neutral.If pH > 7, the solution basic.∵ pH = 3.5 < 7.
∴ The solution is acidic.
4) During the course of the day, human saliva varies between being acidic and basic. If [OH⁻] = 3.16 x 10⁻⁸ M,
a) Find [H⁺]
∵ [H⁺][OH⁻] = 10⁻¹⁴.
∴ [H⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(3.16 x 10⁻⁸ M) = 3.16 x 10⁻⁷ M.
b) What is the pH?
∵ pH = - log[H⁺].
[H⁺] = 3.16 x 10⁻⁷ M.
∴ pH = - log(3.16 x 10⁻⁷ M) = 6.5.
c) Is the solution acidic, basic, or neutral?
We can determine the nature of the solution, acidic, basic or neutral, from the value of the pH.pH is a scale from 0 to 14.
If pH < 7, the solution is acidic.If pH = 7, the solution is neutral.If pH > 7, the solution basic.∵ pH = 6.5 < 7.
∴ The solution is acidic.
As an alternative energy source, nuclear energy is more harmful to the environment than a coal-fired power plant because it produces more mercury, air pollution, and carbon dioxide.
True
or
false
Answer:
False
Explanation:
It is coal-fired power plants that produce mercury, air pollution, and carbon dioxide.
However, nuclear energy produces radioactive waste that must be stored for many years before it can be safely disposed.
An ideal gas at a given initial state expands to a fixed final volume. would the work be greater if the expansion occurs at constant pressure or at constant temperature? explain.
Answer:
Constant pressure
Explanation:
At constant pressure,
[tex]w = -p\Delta V = -p(V_{f} - V_{i})[/tex]
At constant temperature,
[tex]w = -RT \ln \left(\dfrac{V_{f}}{V_{i}} \right)[/tex]
1 mol of an ideal gas at STP has a volume of 22.71 L.
Let's compare the work done as it expands under each condition from an initial volume of 22.71 L.
Isobaric expansion
[tex]w = -100p(V_{2} - 22.71}); \text{(1 bar$\cdot$L = 100 J)}[/tex]
A plot of -w vs V₂ gives a straight line (red) with a constant slope of 100 J/L as in the diagram below (Note that w is work done on the system, so -w is the work done by the system). \
Isothermal expansion
[tex]w= -8.314 \times 273.15 \ln \left(\dfrac{V_{f}}{22.71} \right)\\\\= -2271 \left( \ln V_{f} -\ln22.71 \right)\\= -2271 \left(\ln V_{f} - 3.123 \right)\\= 7092 - 2271\ln V_{f}[/tex]
A plot of -w vs V₂ is a logarithmic curve. Its slope starts at 100 J/mol but decreases as the volume increases (the blue curve below).
Thus, the work done during an expansion at constant pressure is greater than if the system is at constant temperature.
What natural processes produce large quantities of co2
Answer:
here are both natural and human sources of carbon dioxide emissions. Natural sources include decomposition, ocean release and respiration. Human sources come from activities like cement production, deforestation as well as the burning of fossil fuels like coal, oil and natural gas.
Explanation:
The majority of the carbon dioxide emitted into the atmosphere comes from natural sources. The oceans emit the most carbon dioxide per year of any natural or human-caused source.
What are the ways that carbon dioxide released into environment?Carbon dioxide is naturally added to the atmosphere by organisms respiring or decomposing (decaying), carbonate rocks weathering, forest fires, and volcanoes erupting.
Carbon dioxide is also released into the atmosphere as a result of human activities such as the combustion of fossil fuels and the destruction of forests, as well as the manufacture of cement.
Electricity and heat, agriculture, mass transit, forestry, and manufacturing are the primary sources of greenhouse gas emissions worldwide. Energy production in general accounts for 72 percent of total emissions.
Natural sources account for the vast majority of carbon dioxide emissions into the atmosphere. The oceans transmit one of most Carbon dioxide per year of any natural or man-made source.
Thus, this is the natural processes that produce large quantities of carbon dioxide.
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An empty fuel tank can still contain ________ and therefore can be even more dangerous than one full of liquid fuel.
Answer:
An empty fuel tank can still contain "fumes"
Explanation:
Even if there is not enough liquid fuel, whatever is left in the tank creates fumes, which is more combustible than liquid gas.
Answer:
Fumes / vapors.
Explanation:
An empty tank appears to be non dangerous as it has no liquid fuel. However even if tank is empty there may be some drops of left over liquid fuel.
These drops make the container filled with dangerous vapors that are more prone to catch fire as compared to gasoline.
Even a small spark may cause a severe explosion.
at element makes up all organic compounds?
Answer:
The element that makes up all organic compounds is carbon (C)Explanation:
The term organic matter refers to the matter in the living organisms. Nowadays, organic compounds, the object of organic chemistry, are the compounds that contain carbon except carbon oxides, carbides and carbonates (which are considered inorganic compounds).
Organic compounds form a vast variety of vital compounds based on the versatility of carbon atoms.
Carbon atoms have four valence electrons which can form a variety of single, double, and triple bonds with it self, to form long chains.
Carbon atoms can also form bonds with other elements like, hydrogen, oxygen, nitrogen, halogens, among others, to form different kind of compounds: alkanes, alkenes, alkynes, alcohols, aldehydes, esters, eters, amines, amides, polymers, among others.
Thus, organic compounds form a vast subject of study based on the special chemical properties of carbon.
The biosphere of the earth is made up of _______compounds.
A. Inorganic
B. Organic
Answer:
B.
Explanation:
When we say "biosphere", we're referring to the atmosphere, geosphere, lithosphere and hydrosphere, and everything in them. You've probably heard of these in class as the "pillars of Earth" or the "pillars of our planet". In other words, when we talk about biosphere we're talking about life.
Organic compounds are all of the compounds that contain carbon, C, in them. You might know that CHNOPS* are the "7 molecules of life", and you might have noticed that Carbon stands first in the list, and that's not because it makes up a mnemonic, Carbon is indeed the most important one in many ways.
*Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulfur.
Hope it helped,
BiologiaMagister
Answer:
Organic :)
Explanation:
Choose the atom with the largest atomic radius. CI, S, Na,SI
Answer:
Na
Explanation:
Cl, S and Na are all in the same period.
The further left an element is in a row of the periodic table, the larger its atomic radius.
Answer:
Na
Explanation:
Bohr’s model could only explain the spectra of which type of atoms?
bonded atoms with one electron
bonded atoms with more than one electron
single atoms with one electron
single atoms with more than one electron
single atoms with more than one electron
Answer:
Explanation:
Bohr’s model could only explain the spectra of single atoms with one electron.
Bohr’s model:
It shows that the negatively charged electrons orbit the positively charged nucleus in a fixed circular path.
Bohr’s model also known as the planetary model because it resembles as solar system model.Bohr use the Hydrogen spectra to form its model.
Therefore, Bohr’s model could only explain the spectra of single atoms with one electron.
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A flask contains methane, chlorine, and carbon monoxide gases. The partial pressures of each are 0.215 atm, 50 torr, and 0.826 respectively. What is the total pressure in the flask?
Answer:
1.11 Atm or 1.0168Atm or 841.168 Torr or 841 Torr
Explanation:
we are using Daltons partial pressure is equal to the sum of the partial pressures of the individual gases. you must convert the Torr to Atm
Which aqueous solution of KI freezes at the lowest temperature? 1) 1 mol of KI in 500. g of water
2) 2 mol of KI in 500. g of water
3) 1 mol of KI in 1000. g of water
4) 2 mol of KI in 1000. g of water
Answer:
2) 2 mol of KI in 500. g of water.
Explanation:
Adding solute to water causes depression of the boiling point.The depression in freezing point (ΔTf) can be calculated using the relation:
ΔTf = i.Kf.m,
where, ΔTf is the depression in freezing point.
i is the van 't Hoff factor.
van 't Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass. For most non-electrolytes dissolved in water, the van 't Hoff factor is essentially 1. (i for KCl = 2/1 = 2).
Kf is the molal depression constant of water (Kf = 1.86°C/m).
m is the molality of the solution.
All parameters (i, and Kf) are constant, m is the variable.ΔTf ∝ m.
molality (m) of a solution is the no. of moles of dissolved solute in a 1.0 kg of the solvent.
We need to calculate the molality of each solution:
1) 1 mol of KI in 500. g of water :
m of this solution = (no. of moles)/(mass of the solution(kg) = (1.0 mol)/(0.5 kg) = 2 m.
∴ ΔTf = i.Kf.m = (2)(1.86°C/m)(2 m) = 7.44°C.
∴ Freezing point of the solution = 0.0°C - 7.44°C = - 7.44°C.
2) 2 mol of KI in 500. g of water :
m of this solution = (no. of moles)/(mass of the solution(kg) = (2.0 mol)/(0.5 kg) = 4 m.
∴ ΔTf = i.Kf.m = (2)(1.86°C/m)(4 m) = 14.88°C.
∴ Freezing point of the solution = 0.0°C - 14.88°C = - 14.88°C.
3) 1 mol of KI in 1000. g of water :
m of this solution = (no. of moles)/(mass of the solution(kg) = (1.0 mol)/(1.0 kg) = 1 m.
∴ ΔTf = i.Kf.m = (2)(1.86°C/m)(1 m) = 3.72°C.
∴ Freezing point of the solution = 0.0°C - 3.72°C = - 3.72°C.
4) 2 mol of KI in 1000. g of water:
m of this solution = (no. of moles)/(mass of the solution(kg) = (2.0 mol)/(1.0 kg) = 2 m.
∴ ΔTf = i.Kf.m = (2)(1.86°C/m)(2 m) = 7.44°C.
∴ Freezing point of the solution = 0.0°C - 7.44°C = - 7.44°C.
So, the aqueous solution of KI freezes at the lowest temperature is:
2) 2 mol of KI in 500. g of water.
Option 2, which contains 2 mol of KI in 500 g of water, will freeze at the lowest temperature due to the highest concentration of solute particles, resulting in the largest freezing point depression.
The lowest temperature at which an aqueous solution of KI will freeze is determined by the solution that has the highest concentration of solute particles (ions) in water. Freezing point depression is directly proportional to the molality of the solution, and since KI dissociates into K+ and I- ions in water, each mole of KI will yield two moles of ions.
Comparing the options given:
Option 1 has 1 mol of KI which yields 2 mol of ions in 500 g of water.Option 2 has 2 mol of KI which yields 4 mol of ions in 500 g of water - resulting in the highest concentration and thus the largest freezing point depression.Option 3 has 1 mol of KI in 1000 g of water, so the concentration is lower than in option 1.Option 4 has 2 mol of KI in 1000 g of water, which is double the amount of water compared to option 2, leading to a lower ion concentration.Therefore, option 2 (2 mol of KI in 500 g of water) would result in the lowest freezing temperature due to having the highest concentration of ions that causes the greatest freezing point depression.
Compared to the Apollo program, the Space Shuttle has been
A. a complete failure.
B. much more successful.
C. considered a mixed success.
D. able to explore much more of the solar system.
your answer is C. considered a mixed success.
Milk of magnesia (maalox) contains magnesium hydroxide. magnesium hydroxide can be reacted with hydrochloric acid to form magnesium chloride and water, as seen in the reaction below. using this reaction, how many grams of hydrochloric acid are needed to fully react 355g magnesium hydroxide?
The chemical reaction described by the question:
[tex]Mg(OH)_{2} + 2HCl = MgCl_{2} + 2H_{2}O[/tex]
Then for finding the number of moles of magnesium hydroxide Mg(OH)[tex]_{2}[/tex]
number of moles = mass (grams) / molecular mass (g/mole)
number of moles of Mg(OH)[tex]_{2}[/tex] = 355 / 58 = 6.12
From the chemical reaction:
1 mole of Mg(OH)[tex]_{2}[/tex] reacts with 2 moles of HCl
6.12 moles of Mg(OH)[tex]_{2}[/tex] reacts with x moles of HCl
x = (6.12×2)/1 = 12.24 moles of HCl
And now we can determine the mass of hydrochloric acid HCl
mass (grams) = number of moles x molecular mass (grams/mole)
mass of HCl = 12.24 × 36.5 = 446.76 g
Final answer:
To determine the mass of hydrochloric acid needed to react with 355g of magnesium hydroxide, we use stoichiometry based on their molar masses to calculate that 444.09 grams of hydrochloric acid are required.
Explanation:
The student is asking how many grams of hydrochloric acid (HCl) are needed to fully react with 355g of magnesium hydroxide (Mg(OH)2). To solve this, we'll use the reaction equation:
Mg(OH)2 + 2HCl → MgCl2 + 2H2O
First, we need to find the molar mass of Mg(OH)2 (24.305 + 2(15.999) + 2(1.008) = 58.319 g/mol) and HCl (1.008 + 35.45 = 36.458 g/mol).
Next, we calculate the moles of Mg(OH)2 used using its molar mass:
355g Mg(OH)2 × (1 mol/58.319 g) = 6.09 mol Mg(OH)2
According to the balanced equation, 1 mole of Mg(OH)2 reacts with 2 moles of HCl. Thus:
6.09 mol Mg(OH)2 × (2 mol HCl/1 mol Mg(OH)2) = 12.18 mol HCl
Finally, we find the mass of HCl needed:
12.18 mol HCl × (36.458 g/mol) = 444.09 g HCl
Therefore, 444.09 grams of hydrochloric acid are needed to fully react with 355g of magnesium hydroxide.
Insoluble substances can dissolve in all solvents. True or false
Answer:
The answer to your question is False.
Explanation:
An insoluble substance cannot dissolve
Final answer:
The statement is false; insoluble substances by definition do not readily dissolve in solvents, and solubility depends on the 'like dissolves like' principle where substances dissolve in solvents with similar intermolecular forces.
Explanation:
The statement that insoluble substances can dissolve in all solvents is false. An insoluble substance is defined as a solute that does not dissolve in a solvent. While it is true that no solid is perfectly insoluble and most have some small level of solubility in a solvent, the term 'insoluble' is used to describe substances that do not dissolve to any significant extent. The solubility of a substance largely depends on the similarity in intermolecular forces between the solute and the solvent, which is summarized by the rule 'like dissolves like'.
Nonpolar substances are generally soluble in nonpolar solvents, whereas polar and ionic substances are more likely to dissolve in polar solvents. For example, table salt (NaCl), which is ionic, dissolves well in water because they are both polar. However, nonpolar substances, such as oil, do not mix with water because they are not soluble in polar solvents. Moreover, there are scenarios where an 'insoluble' substance can exhibit a degree of solubility due to the hydrotropic action of water, enabling otherwise insoluble substances to dissolve at least slightly in water.
In summary, some substances can dissolve to an extent in certain solvents due to the 'like dissolves like' principle, but insoluble substances by definition do not dissolve readily in any solvents to form true solutions.
The forensic technician at a crime scene has just prepared a luminol stock solution by adding 15.0 g of luminol into a total volume of 75.0 mL of H2O. What is the molarity of the stock solution of luminol?
Answer:
1.13 M.
Explanation:
Molarity (M) is defined as the no. of moles of solute dissolved in a 1.0 L of the solution.M = (no. of moles of luminol)/(Volume of the solution (L).
∵ no. of moles of luminol = (mass/molar mass) of luminol = (15.0 g)/(177.16 g/mol) = 0.085 mol.
Volume of the solution = 75.0 mL = 0.075 L.
∴ M = (no. of moles of luminol)/(Volume of the solution (L) = (0.085 mol)/(0.075 L) = 1.13 M.
A pan containing 30 grams of water was allowed to cool from a temperature of 90.0 °C. If the amount of heat released is 1,500 joules, what is the approximate final temperature of the water?
A. 76 °C
B. 78 °C
C. 81 °C
D. 82 °C
Answer:
B. 78 °C.
Explanation:
To solve this problem, we can use the relation:Q = m.c.ΔT,
where, Q is the amount of heat released from water (Q = - 1500 J).
m is the mass of water (m = 30.0 g).
c is the specific heat capacity of water (c = 4.18 J/g.°C).
ΔT is the difference between the initial and final temperature (ΔT = final T - initial T = final T - 90.0 °C).
∴ (- 1500 J) = (30.0 g)(4.18 J/g.°C)(final T - 90.0 °C)
∴ (final T - 90.0 °C) = (- 1500 J)/(30.0 g)(4.18 J/g.°C) = - 11.96°C.
∴ final T = 90.0 °C - 11.96°C = 78.04°C ≅ 78 °C.
So, the right choice is: B. 78 °C.
Answer:
78 °C
Explanation:
I took the test and got it correct. hope this helps
Which element is least likely to undergo a chemical reaction
Answer:
Neon is the least likely to undergo chemical reaction.
Explanation:
The other elements given in the option do not have 8 electrons in their outermost shell, so they will be quite willing to undergo chemical reactions in order to become stable.
What is the maximum magnification of a compound light microscope?
Answer: 100x
Explanation:
The actual power or magnification of a compound optical microscope is the product of the powers of the ocular (eyepiece) and the objective lens. The maximum normal magnifications of the ocular and objective are 10× and 100× respectively, giving a final magnification of 1,000×.