1) amount of energy required to change 1 gram of material from the solid to the liquid state at its melting point - latent heat of fusion.
The temperature at which the phase transition occurs is the melting point or the freezing point.
2) a measure of the kinetic energy of the particles of a substance - temperature.
Temperature is the intensity of heat present in a substance and a thermometer is a device that measures temperature or a temperature gradient.
3) the amount of energy required to change 1 gram of a substance 1°C - specific heat.
Heat capacity of a sample is expressed in units of thermal energy per degree temperature (J/K).
Heat capacity is often defined relative to a unit of mass (J/kg·K or J/g·K), prefixed with the term specific.
For example, specific heat capacity of water is 4.184 J/g·K (Cp(H₂O) = 4.184 J/g·K).
4) amount of energy required to change 1 gram of material from the liquid to the gaseous state at its boiling point - latent heat of vaporization.
For example, evaporization is phase change process in which the water changes from a liquid to a gas (water vapor). Solar radiation is the source of energy for evaporation.
5) the amount of heat energy required to raise the temperature of 1 gram of liquid water from 14.5°C to 15.5°C - calorie.
Calorie (cal), or small calorie, is the amount of energy needed to heat one gram of water by one degree Celsius.
One small calorie is approximately 4.2 joules.
A calorie is a unit of energy.
Suppose the volume of a container is decreased, but the same number of gas molecules is present at the same temperature. What will happen to the molecules?
The molecules will increase in number.
The molecules will decrease in number.
There will be more molecules per unit volume.
There will be less molecules per unit volume.
Answer: Option (C) is the correct answer.
Explanation:
When the volume of a container is decreased and same number of gas molecules are present inside the container at the same temperature then it means that more number of gas molecules are spread per unit volume.
As earlier when the volume of container was more then the molecules were widely spread inside the container but on decreasing the volume of container, molecules come closer to each other and hence there will be increase in molecules per unit volume.
Answer:
It is C
Explanation:
How much heat can be obtained from the condensation of 36.2 g of methanol vapor (MM = 32.04 g/mol) at its boiling point to 36.2 g of liquid methanol at the same temperature? â†Hvap = 35.2 kJ/mol Cliquid = 2.533 J/gâ—¦C Cgas = 44.06 J/gâ—¦C
Answer:
q = -39.8 kJ
Step-by-step explanation:
CH₃OH(g) ⇌ CH₃OH(l); ΔH(cond) = -35.2 kJ·mol⁻¹
(1) Calculate the moles of methanol
n = 36.2 × 1/32.04
n = 1.130 mol
=====
(2) Calculate the heat evolved
q = nΔH(cond)
q = 1.130 × (-35.2)
q = -39.8 kJ
2AgNO3 (s) + MgCl2 (aq) --> 2AgCl (s) + Mg(NO3)2 (aq) The student starts with 50.0 grams of mgcl2 and an excess of AgNO3. If she makes 125.1g of AgCl, what is her percent yield?
The percent yield is 83.12%
calculation
percent yield = actual yield / theoretical yield x 100
actual yield =125.1 g
Theoretical yield is calculated as below
Step 1: find the moles of MgCl₂
moles = mass÷ molar mass
from periodic table the molar mass of mgCl₂ =24.3 +(35.5 x2) =95.3 g/mol
moles = 50.0 g÷ 95.3 g/mol =0.525 moles
Step 2: use the mole ratio to determine the moles of AgCl
from given equation MgCl₂: AgCl is 1:2
therefore the moles of AgCl = 0.525 x2/1 =1.05 moles
Step 3: find the theoretical mass AgCl
mass = moles x molar mass
from periodic table the molar mass of Agcl = 107.87 +35.5 =143.37 g/mol
mass = 1.05 moles x 143.37 g/mol =150.5 grams
The percent yield is therefore = (125.1 g/150.5) x 100 = 83.12%
A 0.3000-g sample of soda ash (which contains sodium carbonate) is dissolved in 50.00 mL of water. Titration with standard 0.1000 M HCl required 42.70 mL of the acid to neutralize the soda ash solution. What is the percent by mass of sodium carbonate in the soda ash sample? The molar mass of sodium carbonate is 105.99 g/mol. The equation for the reaction of sodium carbonate and hydrochloric acid is
How do forensic scientists determine the time of death? There are timely pieces of evidence that help scientists with this task. At the time of death:
~The heart stops
~The skin gets tight and grey in color
~Cell start to die (brain 3-7 min; skin up 24 hours)
~The muscles relax
~The bladder and bowels empty
And then what? Order these changes from FIRST to LAST.
I have done some research as well as asking some friends. This is what I came up with. Not sure if it is 100% correct.
step = time after death
1. Livor Mortis = 20-30 minutes
2. Eyes film (cloud) = 2 hours
3. Rigor Mortis begins = 4-6 hours
4. Empty small intestines = 12 hours
5. Bloating = 3-5 days
6. Decay
Forensic scientists determine the time of death initially by observing physical changes such as the heart stopping, greying of the skin, cell death, muscle relaxation, and the emptying of the bladder and bowels. The sequence of these events helps establish a timeline. Additional factors like insect activity, weather conditions, and the setting may further assist in making an accurate estimation.
Explanation:Forensic scientists, specifically forensic anthropologists and forensic pathologists, determine the time of death by analyzing various changes that occur in the body after death. These changes occur in a specific sequence and at different rates, thereby providing a means to estimate the time of death. The sequence of changes are as follows:
The heart stops: The absence of a heartbeat may be the most immediate signal of death.The skin gets tight and grey in color: This happens immediately after the heart stops. The greying is due to blood pooling and coagulating in the body after the heart stops pumping.Cell death begins: Brain cells start dying within 3-7 minutes of the heart stopping due to a lack of oxygen. Skin cells can survive up to 24 hours after death.Relaxation of the muscles: Shortly after death, all the muscles in the body relax. Rigor mortis, or the stiffening of the muscles, begins 3-4 hours after death and can last up to 72 hours.Emptying of the bladder and bowels: This is not always immediate and can occur at various times postmortem, usually within the first few hours to a day.In addition to these changes, forensic scientists also study other evidence such as insect activity, weather conditions and surroundings to calculate the postmortem interval or to validate their findings based on the body's changes.
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why do comets have tails
As a comet approaches the Sun, it starts to heat up. The ice transforms directly from a solid to a vapor, releasing the dust particles embedded inside. Sunlight and the stream of charged particles flowing from the Sun – the solar wind – sweeps the evaporated material and dust back in a long tail.
Answer:
Comets are composed of ice, dust and frozen gases. The core of the comet is known as nucleus which is formed of rocks and frozen gases. Coma is the atmosphere of the comet. As the comet enters the inner solar system, the coma expands due to sublimation of frozen gases. As it nears the sun, the coma extends backwards and forms a long tail. It extends backwards due to the solar wind. The charged particles from the sun take away the evaporated material and dust of the comet backwards forming tail.
When so much solute is added that no more will dissolve, what type of solution has been created? NEED HELP ASAP
The simplest answer and the correct one is saturated. You can try this at home to see what it looks like. Take a glass and fill it to the 1/2 full mark. Make sure the water is on the coolish side. Start putting measured amounts of salt in the water. Do this until you see salt on the bottom of the glass. The solution is now saturated.
Empty the glass. Put the same amount of water in the glass but make it much warmer. Put the same amount of salt in the glass. It should not be saturated -- that is there should be no salt on the bottom.
So temperature determines saturation. But more important, you should get an idea of what saturation is.
Copper wire is used in electrical wiring because the metallic bonding between the atoms aids with the ___________ of the material.
Final answer:
Copper wire is used in electrical wiring because its metallic bonding aids with conductivity of the material.
Explanation:
The metallic bonding between the atoms aids with the conductivity of the material.
Copper wire is used in electrical wiring because it has high electrical conductivity. Metallic bonding is responsible for the free flow of electrons in copper, allowing it to conduct electricity efficiently. This property makes copper an ideal material for conducting electric current in various appliances.
PLEASE HELP! 25 POINTS!!!! I got the #1, just not #2 and #3. An industrial chemical company has opened a new plant that will produce ammonia (NH3). Hydrogen and nitrogen gases are reacted to produce the ammonia. For the first batch of ammonia production, 475 g of nitrogen is reacted with excess hydrogen, and 397 g of ammonia are produced.
• Write the balanced equation for the formation of ammonia from hydrogen and nitrogen.
3H2+N2-->2NH3
• Calculate the theoretical yield of ammonia. Work must be shown to earn credit.
• Calculate the percent yield for the ammonia production. Work must be shown to earn credit.
Answer :
Part (a) : [tex]3H_2(g)+N_2(g)\rightarrow 2NH_3(g)[/tex]
Part (b) : Theoretical yield of [tex]NH_3[/tex] = 440.96 g
Part (c) : Percentage yield of ammonia is 90.03 %
Mass of [tex]N_2[/tex] = 475 g
Molar mass of [tex]N_2[/tex] = 28 g/mole
Molar mass of [tex]NH_3[/tex] = 17 g/mole
Experimental yield of [tex]NH_3[/tex] = 397 g
Part (a) :The balanced chemical reaction will be:
[tex]3H_2(g)+N_2(g)\rightarrow 2NH_3(g)[/tex]
Part (b) :To calculate the moles of [tex]N_2[/tex]:
[tex]\text{Moles of }N_2=\frac{\text {Mass of }N_2}{\text{ Molecular mass of }N_2}=\frac{475g}{28g/mole}=16.96moles[/tex]
From the given balanced equation:
1 mole of [tex]N_2[/tex] gas produces 2 moles of [tex]NH_3[/tex]
16.96 moles of [tex]N_2[/tex] gas produces [tex]\frac{2}{1}\times 16.96=33.92[/tex] moles of [tex]NH_3[/tex]
Now we have to calculate the mass of [tex]NH_3[/tex]
[tex]\text{ Mass of }NH_3=\text {Moles of }NH_3\times \text{ Molar mass of }NH_3[/tex]
[tex]\text{ Mass of }NH_3=(33.92moles)\times (17g/mole)=440.96g[/tex]
Therefore, the theoretical yield of [tex]NH_3[/tex] gas = 440.96 g
Part (c) : Percentage yield :
[tex]\% \text{ yield of }NH_3=\frac{\text {Experimental yield of NH_3}}\text {Theoretical yield of }NH_3\times 100[/tex]
[tex]\% \text{ yield of }NH_3=\frac{397g}{440.96g}\times 100=90.03\%[/tex]
Therefore, the % yield of ammonia is 90.03 %
For the reaction Na + H2O → NaOH + H2, what are the reactants, products, and correct coefficients in the balanced equation? Reactants: 1Na and 1H2O; products: 1NaOH and 1H2 Products: 2Na and 1H2O; reactants: 2NaOH and 1H2 Products: 3Na and 2H2O; reactants: 3NaOH and 2H2 Reactants: 2Na and 2H2O; products: 2NaOH and 1H2
The correct answer is reactants 2Na and 2H₂O and products 2NaOH and 1H₂.
The given unbalanced chemical equation is:
Na (s) + H2O (l) → NaOH (aq) + H₂ (g)
From the equation, it can be seen that there are three atoms of hydrogen on the products side, however, only two on the reactant's side. So, in order to balance the equation, one needs to multiply the sodium hydroxide by 2 to get a total of 4 atoms of hydrogen on the product's side.
This will enable one to readily double the number of molecules of water to get 4 atoms of hydrogen on the reactants side, and then balance the atoms of sodium by multiplying the sodium metal by 2. The balanced equation obtained is:
2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂ (g)
In the given chemical reaction, Reactants: 2Na and 2H₂O and Products: 2NaOH and 1H₂. Therefore, option D is correct.
In the balanced equation, the coefficients indicates the relative number of moles of each substance involved in the reaction. The balanced equation for the reaction between sodium (Na) and water (H₂O) to produce sodium hydroxide (NaOH) and hydrogen gas (H₂) is: 2Na + 2H₂O → 2NaOH + H₂
This balanced equation shows that 2 moles of sodium reacts with 2 moles of water to produce 2 moles of sodium hydroxide and 1 mole of hydrogen gas.
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of the following is a force acting between objects that do not touch? (3 points)
Normal force
Frictional force
Electrical force
Applied force
Which element has the strongest intermolecular forces at room temperature? A) I (s) B) F (g) C) Br (l) D) Cl (l)
A) I or Iodine
Iodine is solid which will be in a more fixed position and held closer together making it harder to break apart. It has more electrons and therefore more van der waals forces acting on it, which require more energy to break apart.
answer: a. I
explanation: iodine is a solid meaning the particles are closer together and holds a more fixed position, making it harder to break apart unlike a liquid or gas where the particles are more spread apart
When the equation Fe3O4+AI > AI2O3+Fe is correctly balanced what is the coefficient of Fe
The answer is 9 please rate 5 ⭐️ if it was helpful.
During chemistry, Dan mixes two clear, colorless solution and mixing them produces a yellow precipitate in a clear, colorless final solution as shown by the chemical equation.
Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq)
What physical evidence indicates that there has been a chemical reaction?
Answer: Formation of precipitate indicates that there has been a chemical reaction.
Explanation:
Chemical reaction: It is defined as change in arrangement of the atoms so as to form a new substance.
Mixing of two clear solutions that is lead nitrate and potassium iodide gives out yellow solid precipitate of lead iodide with aqueous solution of potassium nitrate.
[tex]Pb(NO_3)_2(aq)+2KI(aq)\rightarrow PbI_2(s)+2KNO_3(aq)[/tex]
The physical evidence which indicates that chemical reaction has been taken place is formation of yellow solid precipitate of lead iodide ,([tex]PbI_2[/tex]).
A single atom of an element has 21 nutrons 20 electtons and 20 protons which element is it
your element would be calcium
A substance registers a temperature change from 20°c to 40°c. to what incremental temperature change does this correspond?
The incremental temperature change is 20°C or 50%.
What is incremental temperature change ?Incremental temperature change is the change in the temperature of any substance when it is increased from its original temperature. Incremental temperature change is always measured as percentage increase in the rate of temperature.
How to calculate the incremental temperature change ?Temperature is increased from 20°C to 40°C .
Thus incremental change in temperature,
ΔT = Final temperature - Initial temperature
∴ ΔT = 40°C - 20°C = 20°C
Also percentage change in temperature ,
(ΔT / Final temperature) × 100 %
⇒ (20°C / 40°C) × 100 %
⇒ (1/2) × 100 %
∴ Percentage change = 50%
Thus incremental temperature change is 20°C or 50%
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How can two atoms of the same chemical element be different?
A.They may be different isotopes of the element. Each isotope of the same element has a different number of electrons.
B.They may be different isotopes of the element. Each isotope of the same element has a different number of neutrons.
C.They may be different allotropes of the element. Each allotrope of the same element has a different number of electrons.
D.They may be different allotropes of the element. Each allotrope of the same element has a different number of neutrons.
The answer is B as isotopes are different versions of the same chemical element containing the same amount of protons and electrons but different amounts of neutrons.
A volcano erupts which term best describes the rock that will eventually form on the surface
What is the three-dimensional shape of the molecule with this Lewis structure.
H-Be-H
A. Bent
B. Linear
C. Tetrahedral
D. Trigonal Plannar
I would have to say B. Linear
I hope this helps!
Cheers, July.
Answer : The correct option is, (B) Linear
Explanation :
Formula used :
[tex]\text{Number of electrons}=\frac{1}{2}[V+N-C+A][/tex]
where,
V = number of valence electrons present in central atom
N = number of monovalent atoms bonded to central atom
C = charge of cation
A = charge of anion
Now we have to determine the hybridization of the [tex]BeH_2[/tex] molecules.
[tex]\text{Number of electrons}=\frac{1}{2}\times [2+2]=2[/tex]
The number of electrons is 2 that means the hybridization will be [tex]sp[/tex] and the electronic geometry of the molecule will be linear.
The three-dimensional shape of the molecule with the Lewis structure are shown below.
Triethylenemelamine is used in the plastics industry and as an anticancer drug. Its analysis is 52.93% carbon, 5.92 % hydrogen, 41.15% nitrogen. The molecular mass of triethylenemelamine is 204.2 g/mol. What is its empirical formula? What is its molecular formula?
Assuming total mass to be 100 g
Mass of C = 52.93 g
=> Moles of C = [tex]52.93 g *\frac{1 mol}{12gC} =4.41 mol C[/tex]
Mass of H = 5.92 g
=> Moles of H=[tex]5.92g*\frac{1mol}{1.01g}=5.86molH[/tex]
Mass of N = 41.15 g
=>Moles of N=[tex]41.15g*\frac{1 mol}{14 g}=2.94mol N[/tex]
Simplest mole ratio of the atoms in the compound:
[tex]C_{\frac{4.41mol}{2.94mol} } H_{\frac{5.86mol}{2.94mol} }N_{\frac{2.94mol}{2.94mol} } =C_{1.5}H_{2}N_{1} or(C_{1.5}H_{2}N_{1})_{2}=>C_{3}H_{4}N_{2}[/tex]
Empirical formula mass=[tex](3*12)+(4*1.01)+(2*14)=68.04g[/tex]
Multiple n = [tex]\frac{204.2}{68.04}=3[/tex]
Molecular formula= [tex](Empirical formula)_{n} =(C_{3}H_{4}N_{2})_{3}=C_{9}H_{12}N_{6}[/tex]
Final answer:
The empirical formula of triethylenemelamine is determined to be C₃H₄N₂ based on the given percentage composition. By comparing the molecular mass of triethylenemelamine to the mass of the empirical formula unit, the molecular formula is found to be C₆H₈N₄.
Explanation:
To determine the empirical formula and molecular formula of triethylenemelamine based on its percent composition (52.93% carbon, 5.92% hydrogen, 41.15% nitrogen) and molecular mass (204.2 g/mol), follow these steps:
Calculate the moles of each element based on 100 g of the compound.
For Carbon: (52.93 g / 12.01 g/mol) = 4.41 moles
For Hydrogen: (5.92 g / 1.008 g/mol) = 5.87 moles
For Nitrogen: (41.15 g / 14.01 g/mol) = 2.94 moles
Determine the simplest whole number ratio of the elements by dividing by the smallest number of moles, which in this case is 2.94 moles (N). This gives:
C: 4.41 / 2.94 ≈ 1.5
H: 5.87 / 2.94 ≈ 2
N: 2.94 / 2.94 = 1
Since the ratio needs to be in whole numbers, multiply each by 2 to get C₃H₄N₂ as the empirical formula.
To find the molecular formula, divide the molecular mass of triethylenemelamine (204.2 g/mol) by the mass of the empirical formula unit (C₃H₄N₂ = 3(12.01) + 4(1.008) + 2(14.01) ≈ 84.1 g/mol), getting approximately 2.43. Since molecular formulas must be whole numbers, this indicates the empirical formula must be multiplied by 2, giving C₆H₈N₄ as the molecular formula of triethylenemelamine.
PLEASE HELP ASAP!!THANKS!
Balance the following and label what type of reaction is taking place:
C5H9O + O2? CO2 + H2O
The given reaction is C₅H₉O + O₂ → CO₂ + H₂O
On balancing the equation we get:
20 C₅H₉O + 90 O₂ → 100 CO₂ + 9 H₂O
This is a single replacement type of reaction. A single replacement reaction, also called a single-displacement reaction, refers to a kind of chemical reaction where an element reacts with a compound and occupies the place of another element in that compound.
Menthol is an organic compound that can be made synthetically or extracted from peppermint or other mint oils. Substances that contain menthol can often be distinguished by its unique smell. What would be the safest way to smell unknown compounds to check for the presence of menthol?
Hi!~~
Menthol, with chemical formula C10H20O, is a common compound used in medicine, often natural ones.
The safest way to check for the presence of menthol should be to use your hand. You would waft the substance's fumes toward your hands.
Answer:
Waft the substance's fumes toward you with your hand.
Explanation:
What is the angle between the carbon-chlorine bonds in the phosgene ( cocl2 ) molecule?
Answer: The angle between the carbon-chlorine bonds in phosgene will be 120°
Explanation: Formula used to calculate the hybridization:
[tex]{\text{Number of electron pairs}} =\frac{1}{2}[V+N-C+A][/tex]
where,
V = number of valence electrons present in central atom i.e. carbon = 4
N = number of monovalent atoms bonded to central atom = 2
C = charge of cation = 0
A = charge of anion = 0
For [tex]COCl_2[/tex]
[tex]{\text{Number of electron pairs}} =\frac{1}{2}[4+2-0+0]=3[/tex]
The number of electron pairs are 3 which means that the hybridization will be [tex]sp^2[/tex] and the electronic geometry of the given molecule will be trigonal planar.
The bond angle in this electronic geometry is 120°
The structure of phosgene is attached below.
The angle between the Carbon-Chlorine bonds in the Phosgene molecule (COCl₂) is generally 120 degrees due to the sp² hybridization of the Carbon Atom
Explanation:The phosgene molecule (COCl₂) has a planar shape, with the oxygen atom in the center, bonded to the carbon atom, and the chlorine atoms bonded to either side of the carbon atom. This creates a molecule with a structure in the shape of the letter 'V'. The angle between the carbon-chlorine bonds in the phosgene molecule is typically 120 degrees. This is due to the fact that the carbon atom in the center is sp² hybridized, meaning it has three regions of electron density spread out in a plane, forming angles of 120 degrees with each other.
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For which of the following conversions does the value of the conversion factor depend upon the formula of the substance?
A) moles of any substance to number of particles
B) volume of gas (STP) to moles
C) mass of any substance to moles
D) density of gas (STP) to molar mass
For which of the following conversions does the value of the conversion factor depend upon the formula of the substance?
The answer is C
The answer is: C) mass of any substance to moles.
To converte mass to amount of substances, mass must be divided by molar mass (n = m ÷ M).
Molar mass M represent the mass of a substance divided by the amount of substance. If the formula is not correct, amount of substance is not correct.
For example, calculate molar mass of iron(II) chloride:
Atomic mass of iron is 55.8 g/mol.
Atomic mass of chlorine is 35.5 g/mol.
If compound is FeCl, molar mass would be 55,8 g/mol + 35,5 g/mol = 91,3 g/mlo, that is not correct.
If compound is FeCl₂, malar mass of compound would be:
55,8 g/mol + 2·35,5 g/mol = 126,8 g/mol, that is correct.
Which metal is the best choice for recovering copper (reacting with copper) from the solution? Fe, Ag, Zn, or Al
Answer: The correct option is Aluminium.
Explanation: To recover copper from the solution, we require a metal which can easily displace copper from the solution.
The reactions in which metal displaces another metal in a chemical reaction are known as single displacement reactions. These reactions are studied using reactivity series.
[tex]A+BC\rightarrow AC+B[/tex]
A is more reactive than B.
The metal which lie above in the reactivity series will easily displace the metal which lies below in the reactivity series.
From the given options, Aluminium is the most reactive of all the metals and hence, it is the best choice for recovering copper from its solution.
1. A student represented a water molecule using beads and straws. She connected two black beads and one white bead in a certain manner using straws. Which of the following explains the type of scientific model created by the student?
A. A simulation because it helps visualize the shape of the molecule.
B. A 3-dimensional model because it helps visualize the shape of the molecule.
C. A simulation because it helps understand the movement of atoms in the molecule.
D. A 3-dimensional model because it helps understand the movement of atoms in the molecule.
Answer: Option (b) is the correct answer.
Explanation:
When the student is using beads then he is representing atoms and the straws represent the bond between the atoms.
Therefore, when a model is represented by the given manner then it helps in identifying the geometry or shape of the object. This is because it shows how atoms are arranged in space along with their angle.
Therefore, we can conclude that out of the given options the type of scientific model created by the student is a 3-dimensional model because it helps visualize the shape of the molecule.
The type of scientific model created by the student has been the 3-D model for the visualization of shape. Thus, option B is correct.
The water molecule has been the simplest compound that has been consisted of the two hydrogen atoms bonded with an oxygen atom.
The presence of loan pairs to the oxygen atom has been responsible for the distortion in the linear shape, and the molecule has been present in the inverted geometry.
The model prepared by the student has black beads as the representation of the hydrogen atoms, while white beads as the representation of the oxygen atom. The straws have been the representation of the bonds in the structure.
The model prepared has been capable of demonstrating the arrangement of the elements in the 3-D plane and has been able to elucidate the structure of the molecule. Thus, option B is correct.
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Shannon needs 9 feet of ribbon for an art project. How many inches of ribbon should she buy if she is making 4 projects
432 inches
Each project is 9 feet, and she is making 4 projects, so multiply 9 by 4 to find the number of feet needed. You should get 36. Each foot is equal to 12 inches, so multiply 36 by 12 to get 432 inches.
Answer: 432 inches
Explanation:
Given : length of ribbon needed by Shannon for an art project = 9 feet
As we know : 1 feet = 12 inches
9 feet =[tex]\frac{12}{1}\times 9=108inches[/tex]
Thus if for 1 project , length of ribbon required is = 108 inches
For 4 projects , length of ribbon required is =[tex]\frac{108}{1}\times 4=432inches[/tex]
Thus 432 inches of ribbon should she buy if she is making 4 projects.
Kaila runs competitively. She would like to calculate her average running speed each time she runs. Which data should Kaila record in order to calculate her average running speed?
Answer:
Start and end times; distance run.
Step-by-step explanation:
Average speed = distance/time.
Kaila should record the distance run, the time she started, and the time she ended her run.
The difference between the start and end times gives the time for the run.
If she inserts her numbers into the formula, she will get her average running speed.
Kaila should record the distance she runs and the time it takes to cover that distance to calculate her average running speed using the formula: Average Speed = Distance / Time.
To calculate her average running speed, Kaila should record the distance she runs and the time it takes to cover that distance. The formula for average speed is given by:
Average Speed = Distance / Time
For example, if Kaila runs 400 meters and it takes her 60 seconds to do so, her average speed would be:
Average Speed = 400 meters / 60 seconds = 6.67 meters per second
By consistently recording the distances and times for each of her runs, Kaila can calculate her average speed for each session and track her progress over time.
Evaluate why acids are able to conduct electricity. Then describe which types of acids are better conductors and why.
Acids produce H+ ions in solution.
Since it produces ions in solution and ions can carry current.
Hence acids can conduct electricity as it produces ions in solution.
Strong acids dissociate completly and produce more ions (than weaker acids which do not dissociate completly) so strong acids are better conductors of electricity.
The following solutions are prepared by dissolving the requisite amount of solute in water to obtain the desired concentrations. Rank the solutions according to their respective osmotic pressures in decreasing order assuming the complete dissociation of ionic compounds. Rank from highest to lowest osmotic pressure. To rank items as equivalent, overlap them. 1M C6H12O6, 1M MgCl2, 2M CH3OH, 1M NaCl
Answer:
C₆H₁₂O₆ < NaCl ≈ CH₃OH < MgCl₂
Step-by-step explanation:
The formula for osmotic pressure (Π) is
Π = icRT
If T is constant,
Π = kic
C₆H₁₂O₆:
Π = k × 1 × 1 = k
MgCl₂:
Π = k × 3 × 1 = 3k
CH₃OH:
Π = k × 1 × 2 = 2k
NaCl:
Π = k × 2 × 1 = 2k
The order of osmotic pressures is
C₆H₁₂O₆ < NaCl ≈ CH₃OH < MgCl₂
MgCl₂ > NaCl = CH₃OH > C₆H₁₂O₆ or MgCl₂ > CH₃OH = NaCl > C₆H₁₂O₆.
Further explanationGiven:
1 M C₆H₁₂O₆1 M MgCl₂2 M CH₃OH1 M NaClQuestion:
Rank the solutions according to their respective osmotic pressures in decreasing order assuming the complete dissociation of ionic compounds.
The Process:
The osmotic pressure of a nonelectrolyte solution is calculated as follows:
[tex]\boxed{ \ \pi = MRT \ }[/tex]
The osmotic pressure of an electrolyte solution is calculated as follows:
[tex]\boxed{ \ \pi = MRTi \ }[/tex]
The van't Hoff factor is i = 1 + (n - 1)α, with
n = number of ions, and α = degree of dissociation.In our problem, assuming the complete dissociation of ionic compounds results in α = 100% and i = n.
From the information above, each type of solution can be prepared as follows:
C₆H₁₂O₆ (glucose) and CH₃OH (methanol) are non-electrolyte solutions.MgCl₂ and NaCl are strong electrolyte solutions.[tex]\boxed{ \ MgCl_2 \rightarrow Mg^{2+} + 2Cl^- \ } \rightarrow \boxed{ \ i = n = 3 \ ions \ }[/tex][tex]\boxed{ \ NaCl \rightarrow Na^{+} + Cl^- \ } \rightarrow \boxed{ \ i = n = 2 \ ions \ }[/tex]Now we compare the amount of osmotic pressure from each solution.
1 M C₆H₁₂O₆ ⇒ [tex]\boxed{ \ \pi = 1 \times RT \ } \rightarrow \boxed{ \ \pi = RT \ }[/tex] in atm.1 M MgCl₂ ⇒ [tex]\boxed{ \ \pi = 1 \times RT \times 3 \ } \rightarrow \boxed{ \ \pi = 3RT \ }[/tex] in atm.2 M CH₃OH ⇒ [tex]\boxed{ \ \pi = 2 \times RT \ } \rightarrow \boxed{ \ \pi = 2RT \ }[/tex] in atm.1 M NaCl ⇒ [tex]\boxed{ \ \pi = 1 \times RT \times 2 \ } \rightarrow \boxed{ \ \pi = 2RT \ }[/tex] in atm.From the above results, it can be observed that 2 M CH₃OH and 1 M NaCl have the same osmotic pressure.
Thus, the rank of the solutions according to their respective osmotic pressures in decreasing orders is MgCl₂ > NaCl = CH₃OH > C₆H₁₂O₆ or MgCl₂ > CH₃OH = NaCl > C₆H₁₂O₆.
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Notes:
Colligative properties are physical properties of a solution that depend on the amount of solute expressed as concentration. One of the colligative properties is osmotic pressure (π).Osmosis is a spontaneous process in which a solvent molecule passes through a semipermeable membrane from a dilute solution (lower solute concentration) to a more concentrated solution (higher solute concentration). The pressure that causes the osmosis process to stop is considered osmotic pressure. We can also observe osmotic pressure as the external pressure needed to prevent the osmosis process. The required external pressure is the same as the osmotic pressure of the solution.Learn moreAbout electrolyte and nonelectrolyte solutions https://brainly.com/question/5404753Calculating the pH value of weak base https://brainly.com/question/9040743To make a 0.500 M solution, one could take 0.500 moles of solute and add? https://brainly.com/question/10278982