Calculate the vapor pressure at 50°c of a coolant solution that is 54.0:46.0 ethylene glycol-to-water by volume. at 50.0°c, the density of water is 0.9880 g/ml, and its vapor pressure is 92 torr. the vapor pressure of ethylene glycol is less than 1 torr at 50.0°c.

Answers

Answer 1
Missing question: The liquid used in automobile cooling systems is prepared by dissolving ethylene glycol (HOCH2CH2OH) in water. Ethylene glycol has a molar mass of 62.07 g/mol and a density of 1.115 g/mL at 50.0°C.
If we use 100 mL of solution:
V(ethylene glycol - C₂H₆O₂) = 0,54 · 100 mL = 54 mL.
V(water) = 0,46 · 100 mL = 46 mL.
m(C₂H₆O₂) = 54 mL · 1,115 g/mL = 60,21 g.
n(C₂H₆O₂) = 60,21 g ÷ 62,07 g/mol = 0,97 mol.
m(H₂O) = 46 mL · 0,988 g/mL = 45,45 g.
n(H₂O)  = 45,45 g ÷ 18 g/mol = 2,525 mol.
mole fraction of solvent: 2,525 mol / (2,525 mol + 0,97 mol) =0,722.
Raoult's Law: p(solution) = mole fraction of solvent · p(solvent).
p(solution) = 0,722 · 92 torr = 66,42 tor.

Related Questions

Water is a polar molecule, meaning it carries partial charges (δ or δ–) on opposite sides of the molecule. for two formula units of kbr, drag two potassium ions and two bromide ions to where they would most likely appear based on the grouping of the water molecules in the area provided.

Answers

The side of each water molecule with the oxygen atom uncovered will be marginally negative. 
The side of each water molecule with the hydrogen atoms uncovered will be marginally positive. 
So the two Cl{-} particles will be pulled in to the biggest number of positive charges, which happen in the boxes on the upper right and lower left. 
The two Na{+} particles will be pulled in to the biggest number of negative charges, which happen in the boxes on the upper left and lower right.

[tex]{{\mathbf{K}}^{\mathbf{+}}}[/tex] will be dragged towards the side of [tex]{\mathbf{O}}{{\mathbf{H}}^{\mathbf{-}}}[/tex] while [tex]{\mathbf{B}}{{\mathbf{r}}^{\mathbf{-}}}[/tex] will be dragged towards the side of [tex]{{\mathbf{H}}^{\mathbf{+}}}[/tex]. (Refer to the attached image)

Further explanation:

Electronegativity:

It is defined as the tendency of an atom to attract the shared electrons in the bond towards itself is known as electronegativity. The more electronegative atom will more attract the bonding electrons towards itself than the less electronegative one. Therefore the electrons will spend more time with the more electronegative atom than an electropositive atom. The electronegative atom will acquire the partial negative charge, and the electropositive atom will acquire a partial positive charge.

The polarity of the bond can be estimated by the electronegativity difference [tex]\left({\Delta {\text{EN}}}\right)[/tex]. [tex]\Delta{\text{EN}}[/tex]is the electronegativity difference between the two atoms that are bonded to each other. The formula to calculate [tex]\Delta{\text{EN}}[/tex]in XY bond is as follows:

[tex]{\mathbf{\Delta EN=}}\left({{\mathbf{electronegativity of Y}}} \right){\mathbf{-}}\left({{\mathbf{electronegativity of X}}}\right)[/tex]

Here, X is the electropositive atom and Y is the electronegative atom.

Higher the electronegativity difference between the two atoms, more will be the polarity of the bond and vice-versa.

Water is a polar molecule. Hydrogen atom acquires partial positive charge while oxygen atom is partially negatively charged. So the end of the water molecule with hydrogen is positively charged, and that with oxygen is negatively charged.

In the case of a potassium-bromine bond, bromine is more electronegative than potassium. So the electrons will be more attracted towards bromine due to which it develops a partial negative charge. Potassium, being less electronegative than bromine, in turn, acquires a partial positive charge. This separation of charge results in the formation of a polar bond between potassium and bromine.

So [tex]{{\text{K}}^+}[/tex] will be dragged towards the side of [tex]{\text{O}}{{\text{H}}^-}[/tex] while [tex]{\text{B}}{{\text{r}}^-}[/tex] will be dragged towards the side of [tex]{{\text{H}}^+}[/tex].

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Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Covalent bonding and molecular structure

Keywords: electronegativity difference, electropositive, electronegative, electrons, polar, KBr, K, Br, K+, Br-, H+, OH-, potassium, bromine, hydrogen, oxygen.

How many grams nano3 add to 500g of h20 prepare solution .5 molal nano3?

Answers

Answer is: mass of sodium nitrate is 21,25 g.
m(H₂O) = 500 g · 1 kg/1000 g = 0,5 kg.
b(solution) = 0,500 m = 0,500 mol/kg.
m(NaNO₃) = ?
b(solution) = n(NaNO₃) ÷ m(H₂O).
n(NaNO₃) = 0,500 mol/kg · 0,5 kg.
n(NaNO₃) = 0,25 mol.
m(NaNO₃) = n(NaNO₃) · M(NaNO₃).
m(NaNO₃) = 0,25 mol · 85 g/mol.
m(NaNO₃) = 21,25 g.

What mass of potassium hydroxide is formed when 8.2 g of potassium oxide is added to 1.3 g of water? answer key?

Answers

The reaction occurs by the following equation: 

K20 + H20 = 2KOH 

According to the equation we have following stoichiometric ratio:

n(K2O) : n(H20) = 1 : 1

From it, we can conclude that K2O and water react in same mass ratio.

Now, we have to determine limiting reagent (the one who determines how much the product will arise).

n(K2O)=m/M=8.2/94=0.09 mole

n(H20)=m/M=1.3/18=0.07 mole

So, there are fewer moles of H2O and it will determine the amount of the product.

n(H2O) : n(K0H) = 1 : 2

n(K0H)=n(H2O) x 2 = 0.17 mole

Finally, the was of KOH is:

m(KOH)= n x M = 0.17 x 56= 9.5 g 


In a molecule of methane (ch4), what type of bond joins the carbon atom to each of the hydrogen atoms?

Answers

a polar covalent bond, the electronegativity of carbon is 2.6, and for hydrogen it's 2.1, therefore their bond is polar, but the molecule itself is not, because of its 3D structure

In an experiment, you combine 83.77 g of iron with an excess of sulfur and then heat the mixture to obtain iron(III) sulfide. 2Fe(s) + 3S(s) → Fe2S3(s) What is the theoretical yield, in grams, of iron(III) sulfide?

Answers

Start by looking up the molar mass of each thing in the reaction.

Fe = 55.845  g/mol
S = 32.065 g/mol
Fe2S3 = 207.9 g/mol

Next, convert Fe mas to moles.

83.77 g /  55.845  g/mol = 1.5 mol Fe

Us the stoichiometry (mole ratio) to get to moles product.

2 Fe reactants makes 1 Fe2S3 product

1.5 mol Fe * (1 Fe2S3 / 2 Fe) = 0.75 mol Fe2S3

Now multiply buy the Fe2S3 molar mass to get its weight in grams.

0.75 mol Fe2S3 * 207.9 g/mol = 155.925 g

This is the amount you should theoretically obtain using that much iron.









The theoretical yield of iron (II) sulfide would be 155.92 g

Theoretical yield

It is the total stoichiometric product from a reaction.

From the equation of the reaction:

2Fe(s) + 3S(s) → Fe2S3(s)

The mole ratio of Fe to Fe2S3 is 2:1

Mole of 83.77 g Fe = 83.77/55.85

                               = 1.4999 moles

Equivalent mole of Fe2S3 = 1.4999/2

                                            = 0.75 moles

Mass of 0.75 mole Fe2S3 = 0.75 x 207.9

                                             = 155.92 g

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moves river of ice fresh water made of fallen snow snow compressed to ice This is a list of features of a(n) A) glacier. B) ice age. C) iceberg. D) continent.

Answers

The answer to this is A

The answer is A. Glacier

Approximately how many moles of boron make up 1.20 × 10^24 atoms of boron?

A. 7.22 × 10^47 moles

B. 6.02 × 10^23 moles

C. 5.00 moles

D. 1.99 moles

Answers

1 mol of anything is 6.02 * 10^23 of that substance
x mol = 1.2 * 10^24

x = 1.2 * 10^24/6.02 * 10^23
x = 1.993 mol.

Answer: D <<<<<======

Consider the reaction a + b c +
d. at biochemical equilibrium (25°c, ph of 7), the concentration of a is 0.2 m, the concentration of b is 0.2 m, the concentration of c is 0.8 m, and the concentration of d is 0.8 m. calculate δg and δg° ′ under these conditions.

Answers

when the reaction is at  equilibrium  ∴ΔG = Zero 
now we need to get Δ G°, we can get it from this formula:
ΔG° = - RT㏑K(eq)
when we have R = 8.315 J/mol°K and T in Kelvin = 25+273 = 298
so we need to get the K(eq) from this formula:
K(eq) = concentration of products / concentration of reactants
          = [ C] [ D] / [A] [B]
          = (0.8*0.8) / (0.2*0.2) = 16
by substitution in ΔG° formula:
∴ ΔG° = - 8.315 * 298 *㏑(16) = -6870 Jmol^-1 /1000 = - 6.87 KJ mol^-1

Which is more stable hydroxyl isopropyl or benzhydrol radical?

Answers

the correct answer is Hydroxyl isopropy

The benzhydrol radical is more stable than the hydroxyl isopropyl radical because it can delocalize its unpaired electron through resonance across the aromatic ring, while the hydroxyl isopropyl radical lacks such extensive resonance stabilization.

When considering the stability of hydroxyl isopropyl and benzhydrol radicals, it's important to look at resonance stabilization. Radicals that can delocalize their unpaired electron through resonance are generally more stable. In the case of a benzhydrol radical, also known as a benzylic radical, there is significant stabilization due to the possibility of multiple resonance structures. This is because the unpaired electron in the benzhydrol radical can be delocalized through the aromatic ring's system of conjugated pi bonds.

On the other hand, the hydroxyl isopropyl radical, which is an alkyl radical, lacks the extended conjugated system that allows for such delocalization. While it may have some hyperconjugative stabilization, it does not benefit from the extensive resonance stabilization that the benzhydrol radical enjoys. As such, the benzhydrol radical is more stable than the hydroxyl isopropyl radical due to the resonance effects and the subsequent delocalization of the unpaired electron across the aromatic ring.

Write the chemical reaction that is responsible for the ph of a buffer which contains nh3 and nh4cl. write the reaction in such a way that is appropriate for a ka.

Answers

Final answer:

The pH of a buffer containing NH3 and NH4Cl is determined by the equilibrium between NH4+ and NH3 in water, with the reaction NH4+ (aq) + H2O(l) → H3O+ (aq) + NH3(aq). The reaction demonstrates the action of the ammonium ion as a weak acid, and its Ka is calculated using the Ka = Kw/Kb relationship. The chloride ion does not undergo significant hydrolysis, so it does not affect the pH of the buffer.

Explanation:

The chemical reaction responsible for the pH of a buffer containing NH3 (ammonia) and NH4Cl (ammonium chloride) involves the equilibrium between NH4+ and NH3 in water:

NH4+ (aq) + H2O(l) ⇒ H3O+ (aq) + NH3(aq)

This represents the dissociation of the ammonium ion, which is a weak acid, in water to produce hydronium ions (H3O+) and ammonia. Since ammonia is a weak base, the corresponding acid dissociation constant (Ka) can be calculated using the relation Ka = Kw/Kb, where Kw is the ion product of water and Kb is the base dissociation constant of ammonia.

The chloride ion, being the conjugate base of the strong acid hydrochloric acid (HCl), does not undergo significant hydrolysis in water:

Cl-(aq) + H2O(l) → HCl(aq) + OH−(aq)

Since HCl is a strong acid, the equilibrium constant (Ka) for its conjugate base, Cl-, is essentially zero, which means Cl- does not affect the buffer solution's pH appreciably.

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Scientists often investigate alternative explanations for the data and observations presented, even once a hypothesis has been tested and supported through an experiment. This investigation of alternative explanations ...

Answers

strengthens the evidence and support for a scientific theory

This is your answer

Answer:

Strengthens the evidence and support for a scientific theory.

Explanation:

Hello,

Scientific method provides a compelling tool scientists use to both develop and demonstrate new theories. As it involves both the observation and experimentation towards a specific subject of matter, it turns out convenient to consider alternative explanations substantiating such subject of matter in light of obtaining a more precise explanation for it. In such a way, this investigation of alternative explanations strengthens the evidence and support for a scientific theory.

Best regards.

What is the acid-base equilibrium reaction between ClO– and H2O.

Answers

Chemical reaction: ClO⁻ + H₂O → HClO + OH⁻.
ClO⁻ is base in this chemical reaction and water is acid. According Brønsted–Lowry acid–base theory base is compound that attracts protons (H⁺) and acid (in this chemical reaction water) gives protons.
Ke = [OH⁻] · [HClO] / [ClO⁻].
[OH⁻] - equilibrium concentration.

Explain why c6h5ch2ch2br is not formed during the radical bromination of c6h5ch2ch3. select the single best answer.

Answers

Hi!

The radical bromination reaction of C₆H₅CH₂CH₃ is performed through a mechanism in which radical reactions are involved. This compound is an alkylbenzene compound, and the carbon that is more reactive towards radical bromination is the carbon bonded to the aromatic ring because in the reaction mechanism the intermediaries are stabilized by resonance in the aromatic ring. 

A terminal substitution will not occur because substitution there will not be stabilized by resonance. The compound that will be formed in this reaction would be:

C₆H₅CH₂CH₃ + Br₂ → C₆H₅CH₂(Br)CH₃ + HBr

Final answer:

C6H5CH2CH2Br is not formed during the radical bromination of C6H5CH2CH3 because the intermediate benzyl radical, formed at the carbon adjacent to the aromatic ring, is much more stable than the primary radical needed for the other product. Selectivity is due to bromine's preference for stable radicals, supported by Hammond's postulate.

Explanation:

The reason why C6H5CH2CH2Br is not formed during the radical bromination of C6H5CH2CH3 involves the relative stability of the radical intermediate. Radical bromination tends to occur at the position that forms the most stable radical, which for a benzyl compound is the carbon atom directly adjacent to the aromatic ring. The radical formed at this position, a benzyl radical, is highly stabilized by resonance. In contrast, the radical that would be required to form C6H5CH2CH2Br is a primary radical, which is less stable and thus less likely to form. This selectivity is due to the fact that bromine radicals are relatively selective and prefer to abstract hydrogen atoms from positions that lead to more stable radical intermediates. Moreover, Hammond's postulate suggests that since the radical formation with bromine is endothermic, the transition state will more closely resemble the stable radical intermediate, leading to more selective radical formation.

Write and balance the chemical equation for the reaction between carbon monoxide, co(g), and oxygen to form carbon dioxide, co2(g). use only integers (not fractions) and be sure to include the states of matter.

Answers

The Original equation for this reaction is:
CO + O2 → CO2
this is not a balanced equation.
as the reactants C = 1 and O= 3
and the products C= 1 and O=2
so we put 1/2 O2 instead of O2 to balance the no. of O atom on
 each side.
CO + 1/2 O2 → CO2 to get the integers number we will multiply by 2 
the final balanced equation is:
2CO(g) +O2(g) → 2CO2(g)
So we finally have 
at the reactants side C atom = 2 & O= 4
at the products side C atom = 2 & O = 4

Final answer:

The balanced chemical equation for the reaction between carbon monoxide (CO) and oxygen (O₂) to form carbon dioxide (CO₂) is 2 CO(g) + O₂(g) → 2 CO₂(g), adhering to the law of conservation of mass.

Explanation:

The reaction between carbon monoxide (CO) and oxygen (O₂) to form carbon dioxide (CO₂) can be represented by the following balanced chemical equation:

2 CO(g) + O₂(g) → 2 CO₂(g)

In balancing this equation, it is important to ensure that the number of each type of atom on the reactants side is equal to the number on the products side. Here, we have two carbon atoms and two oxygen atoms from the CO molecules and two oxygen atoms from the O₂ molecule, giving us a total of four oxygen atoms on the reactants side, which balance with the four oxygen atoms in the two CO₂ molecules on the right side of the equation.

This reaction demonstrates the law of conservation of mass, where the mass of the reactants equals the mass of the products. In this case, the coefficients used are the smallest possible whole numbers that maintain this balance.

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What is the smallest particle of an element that still retains all the properties of the element? a compound a mineral an atom an isotope

Answers

The atom is the smallest particle of an element that retains it's characteristics. Sub-atomic particles such as protons, neutrons and electrons form the atom and it is the amount of each of these sub-atomic particles that make the element that element.

The basic building block of chemistry is known as the atom. The smallest particle of an element that still retains all the properties of the element is known as the atom. The correct option is C.

What is an atom?

The atom can be considered as the basic building blocks of matter which possess the properties of the chemical element. An atom don't exist independently, instead they form ions and molecules which in turn combine in large numbers to form matter.

An atom is an indivisible particle and it contains the sub-atomic particles like protons, electrons and neutrons. The positively charged particles are called protons, the negatively charged particles are called electrons. The neutrons are chargeless particles.

All atoms of the same element are identical but different elements have different types of atoms. The chemical reactions occur when the atoms are rearranged.

Thus the correct option is C.

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The reaction of 0.779 g K with O2 forms 1.417 g potassium superoxide, a substance used in self-contained breathing devices. Determine the formula for potassium superoxide.

Answers

First we need to find the number of moles of both K and O reacted
K - 0.779 g / 39 g/mol
  = 0.02 mol
the mass of O₂ reacted = 1.417 g - 0.779 g = 0.638 g
O₂ moles = 0.638 g / 32 g/mol
               = 0.02 mol 
the number of both K and O₂ moles reacted are equal 
therefore stoichiometry of K to O₂ reacted are 1:1 
then the formula of potassium superoxide is KO₂

Final answer:

The correct formula for potassium superoxide formed when 0.779 g of potassium reacts with an excess of oxygen to form 1.417 g of the compound is[tex]KO_{2}[/tex]

Explanation:

The formula for potassium superoxide can be determined by considering the mass of potassium reacted and the mass of the resultant compound formed. In this case, 0.779 grams of potassium reacts with oxygen to form 1.417 grams of potassium superoxide. Knowing that the potassium has fully reacted and become part of the potassium superoxide, we can deduce that the difference in mass (1.417 g - 0.779 g = 0.638 g) must be due to the oxygen present in the compound.

The simplest ratio between potassium (K) and oxygen (O) that could form a compound would be a 1:1 ratio, which gives us KO. However, based on the provided information, potassium superoxide has a different stoichiometry where 1 mol of potassium reacts with oxygen to form a compound with the formula [tex]KO_{2}[/tex], which is a superoxide. This means there are two oxygen atoms for every potassium atom in the compound.

Therefore, the correct formula for potassium superoxide, as formed in the reaction with an excess of oxygen, is [tex]KO_{2}[/tex].

How many neutrons are found in Cr-54

Answers

Number of neutrons found=Mass number-No. of protons
=54-24
=30
So the answer is 30 neutrons

Answer:

30

Explanation:

To find out the neutron number of an element we must first know what the mass value of that element is and the value of the atom number of that element. To find out these values, just look for the element in the periodic table. Once discovered simply subtract the values using the formula:

No. of neutrons = mass - atom number.

In the case of Cr, the mass is 54, while the atom number is 24. So we can find the number of neutrons.

Cr Neutrons = 54-24 = 30

Match the each term with its definition. 1) reaction coordinate a) the higher point on the energy curve 2) δg° b) the plot of the reaction progress as a function of time 3) δg‡ c) the free energy of the reaction

Answers

The correct answer is:
1) reaction coordinate will match with
B)the plot of the reaction progress as a function of time.

as the reaction coordinate is the progress of a reaction from the reactants to products with different transition states in between. The X-axis: which has the reaction progress reflects the progressive chemical changes and the formation of bond and the bond breakage as S (the energy associated with the reactant) is changing and converting to P ( the energy that associated with the product).Actually, it has no relation to time.Rather partially formation of bonds and breaking of bond reaction steps.

2)ΔG° will match with  
c) the free energy of the reaction.

As it is simply defined as the Gibbs free energy and is also known as a free enthalpy, it is used to calculate the maximum of reversible work performed by the thermodynamic system when the temperature and the pressure are constant.

3)ΔG will match with
A) the higher point of the energy curve.

when ΔG = ΔGproduct - ΔGreactant
and It is simply defined as the change in free energy. It reflects nothing about the speed of the reaction. ΔG+ indicates that the reaction is endergonic and energy goes from reactants to products.and ΔG- become negative when the reaction goes to a lower energy state and it indicates then that the reaction is exergonic.

Draw the acetal produced when ethanol adds to ethanal.

Answers

Structure of acetal is in Word document below.
Acetal is produced when one molecule of aldehyde (in this reaction ethanal) and two molecules of alcohols (in this reaction ethanol) react. Hemiacetal is produced when one molecule of aldehyde and one molecule of alcohol react. Acetals are stable compared to hemiacetals.

Explanation:

Acetals are geminal diethers derivatives of aldehyde formed by the addition to equivalent molecules of an alcohol and removal of water.

When ethanol is added to the ethanal in acidic medium:

Ethanal + Ethanol → Hemiacetal

Hemiacetal + Ethanol → Acetal

Acetal produced when ethanol is added to ethanal are given in the image attached.

Minerals form from bodies of water by the process of _____. precipitation melting cooling condensation

Answers

Precipitation is the answer. i Hope i helped :3

Minerals form from water bodies by the process of [tex]\boxed{{\text{precipitation}}}[/tex].

Further Explanation:

The formation of minerals takes place in several ways. The mineral formation depends on the physical and chemical conditions. These conditions include temperature, pressure, pH, and time.

Precipitation

It is a process by which the dissolved minerals get free from water and as a result deposits are formed. It occurs when dissolved substances come out of water. Minerals form when precipitation takes place in aqueous solutions and from gaseous emissions as in case of volcanic eruptions.

Melting

The process that results in the conversion of any substance from a solid state to the liquid state is known as melting. Another term for this process is fusion.

Cooling

The process of removal of heat by lowering the temperature of any substance is known as cooling.

Condensation

This phase transition occurs when a substance is converted from its gaseous state to the liquid state. Variations in temperature and pressure are done in order to achieve this phase change.

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Answer details:

Grade: Senior School

Chapter: Phase transition

Subject: Chemistry

Keywords: minerals, precipitation, cooling, melting, condensation, pH, temperature, time, pressure, substance, phase transition, gaseous state, liquid state, heat, dissolved minerals, water bodies.

What products are formed from monochlorination of (2r)−2−bromobutane at c1 and c4? draw the products using skeletal structures?

Answers

From monochlorination of (2R)−2−bromobutane at C1 is formed (2S)-2-bromo-1-chlorobutane.

From monochlorination of (2R)−2−bromobutane at C4 is formed (2R)-3-bromo-1-chlorobutane.

According to Cahn-Ingold-Prelog rules, the priority of halogen substituents decreases in the following sequence:

-I > -Br > -Cl > -F

According to the rule, chlorine has priority over bromine, so the configuration changes at C1 substitution.


For a particular first-order reaction, it takes 3.0 minutes for the concentration of the reactant to decrease to 25% of its initial value. what is the value for rate constant (in s-1) for the reaction?

Answers

Final answer:

For a first-order reaction, the rate constant can be determined using the concentration of the reactant at a given time. In this case, the rate constant is 0.25 s^-1.

Explanation:

A first-order reaction is one in which the rate of reaction is directly proportional to the concentration of the reactant. The rate law expression for a first-order reaction is given by rate = k[A], where [A] is the concentration of the reactant and k is the rate constant.

In this case, the concentration of the reactant decreases to 25% of its initial value in 3.0 minutes. We can use this information to determine the rate constant (k).

25% of the initial concentration corresponds to 0.25 times the initial concentration, so the concentration at that time is 0.25[A]. We can substitute this value into the rate law expression and solve for k:

0.25[A] = k[A]

0.25 = k

Therefore, the value for the rate constant (k) for the reaction is 0.25 s-1.

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Final answer:

To find the rate constant (k) for a first-order reaction, we can use the half-life formula. The given information states that it takes 3.0 minutes for the concentration of the reactant to decrease to 25% of its initial value. By substituting these values into the equation, we can find the rate constant.

Explanation:

To determine the rate constant (k) for the first-order reaction, we can use the formula for the half-life of a first-order reaction. The half-life is the amount of time it takes for the concentration of the reactant to decrease to half of its initial value. In this case, it takes 3.0 minutes for the concentration to decrease to 25% of its initial value, which is equivalent to one half-life.

The formula for the first-order half-life is: t1/2 = ln(2)/k
Since the concentration decreases to 25% of its initial value after one half-life, we can use this information to solve for k:

25% = (1/2) * 100% = e-kt1/2
ln(1/2) = -k * t1/2
k = -ln(1/2) / t1/2

Substituting the given values, we have:
k = -ln(1/2) / 3.0 minutes

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Which of the following is a part of a land based carbon cycle ?coral reefs
Crab shells
Trees
Whales

Answers

The appropriate answer is C. Trees. Trees remove carbon dioxide from the atmosphere through the process of photosynthesis. The carbon dioxide is used along with water and energy from the sun to make food for plants.
Corals extract dissolved carbon dioxide from the ocean to secrete their hard rocky structures.
Crab shells and other marine animals with shells have their bodies incorporated into the seafloor when they die. The sea floor eventually gets subducted where it melts. The carbon present here gets back into the atmosphere via volcanic eruptions.

Answer:

c

Explanation:

You are given a crushed sample that is a mixture of limestone (caco3), lime (cao), and sand. the calcium carbonate, limestone, is the only material present in the material that will decompose when heated. you subject a 6.4734 g sample of the mixture to strong heating and after the sample reaches a constant mass (no more mass is lost with additional heating), the sample has a final weight of 4.3385 g. what is the percentage of calcium carbonate present in the original mixture? (f.wt. caco3 = 100.1)

Answers

Answer is: percentage of calcium carbonate is 75%.
Chemical reaction: CaCO₃ → CaO + CO₂.
m₁(sample) = 6,4734 g.
m₂(sample) = 4,3385 g.
m(CO₂) = m₁(sample) - m₂(sample).
m(CO₂) = 6,4734 g - 4,3385 g.
m(CO₂) = 2,1349 g.
n(CO₂) = m(CO₂) ÷ M(CO₂).
n(CO₂) = 2,1349 g ÷ 44 g/mol.
n(CO₂) = 0,0485 mol.
From chemical reaction: n(CO₂) : n(CaCO₃) = 1 : 1.
n(CaCO₃) = 0,0485 mol.
m(CaCO₃) = 0,0485 mol · 100,1 g/mol.
m(CaCO₃) = 4,854 g.
percentage of calcium carbonate = 4,854 g ÷ 6,4734 g · 100%.
percentage of calcium carbonate = 75%.

pls help me!!

Which of the following is a large body in space that orbits a star and does not produce its own light?

Moon
Planet
Sun
Universe

Answers

The planet because the sun reflects off the planet which creates the light.
Planet is the answer and moon is orbit the planet and that doesn't produce light either 

dentify the molecule with the highest boiling point.

CHCl3
OF2
NH3
C6H6

Answers

CHCI3, ion-ion attractions

Answer: Option (c) is the correct answer.

Explanation:

A molecule which has hydrogen bonding will have the highest boiling point. So, out of the given options only [tex]NH_{3}[/tex] will have hydrogen bonding.

Whereas in [tex]CHCl_{3}[/tex] there will be dipole-dipole interactions and no hydrogen bonding within the molecule.

In [tex]OF_{2}[/tex] and [tex]C_{6}H_{6}[/tex], there will be dipole-dipole interaction in both the molecules.

Thus, we can conclude that [tex]NH_{3}[/tex] will have the highest boiling point.

Hexanal would be soluble in water? True or false?

Answers

Answer:

False.

Explanation:

Hexanal is a non-polar compound while water is a polar solvent.

We have the role "Like dissolves like".

So, hexanal is insoluble in water.

H2+I2= 2HI+3 kcal Based on the reaction given above, as the temperature decreases, the formation of the reactants will: A. decrease B. increase C. remained consistent D. indeterminate

Answers

Answer:
Decrease

Explanation:
The reaction given is an exothermic reaction. This means that the heat is a product.
At equilibrium, the rate of forward reaction is equal to the rate of backward reaction.
Now, decreasing the temperature means that the concentration of the products will decrease. 
As a result, the equilibrium will shift to the right leading to the formation of more products in order to reach equilibrium again.
This means that the formation of the reactants will decrease.

Hope this helps :)

the answer is A: decrease

If a propane heater burns 38.95 g C3H8, it consumes 38.95 mol C3H8. 0.8830 mol C3H8. 1 mol C3H8. 44.10 mol C3H8.

Answers

The answer is 0.8830 mol C3H8.

Here's how the answer was generated:

We do know that all the choices are in moles, in that case, we divide the 38.95 g of propane (C3H8) by the molar mass which is:

C = 12.01
H = 1.01

C3H8 = 3 * 12.01 + 8 * 1.01 = 44.11
Divide 38.95 g by 44.11 g/mol and the answer will be 0.8830 mol C3H8. 

Answer:


               Option-2 (0.8830 mol C₃H₈) is the correct answer.


Solution:

                 In statement we are given with the amount of propane gas and are asked to find out the moles for given mass.


As we know mass is related to moles as follow,


                                      Moles = Mass / M.mass ----- (1)


Data Given:


                Moles = ??


                Mass = 38.95 g


                M.mass = (C)3 + (H)8 = (12)3 + (1)8 = 36 + 8 = 44 g/mol


Putting values in equation 1,


                                    Moles = 38.95 g / 44 g/mol


                                    Moles = 0.8854 Moles

If kc = 7.04 × 10-2 for the reaction: 2 hbr(g) ⇌h2(g) + br2(g), what is the value of kc for the reaction: 1/2 h2(g) + 1/2 br2 ⇌hbr(g)

Answers

at the first reaction when 2HBr(g) ⇄ H2(g) + Br2(g)
So Kc = [H2] [Br2] / [HBr]^2
7.04X10^-2 = [H2][Br] / [HBr]^2

at the second reaction when 1/2 H2(g) + 1/2 Br2 (g) ⇄ HBr
Its Kc value will = [HBr] / [H2]^1/2*[Br2]^1/2
we will make the first formula of Kc upside down:
1/7.04X10^-2 = [HBr]^2/[H2][Br2]
and by taking the square root: 
∴ √(1/7.04X10^-2)= [HBr] / [H2]^1/2*[Br]^1/2
∴ Kc for the second reaction = √(1/7.04X10^-2) = 3.769 

The value of Kc for the second reaction is mathematically given as

Kc' = 3.769  

What isthe value of Kc for the second reaction?

Question Parameters:

kc = 7.04 × 10-2 for the reaction

2 hbr(g) ⇌h2(g) + br2(g)

1/2 h2(g) + 1/2 br2 ⇌hbr(g)

Generally, the equation for the reaction  is mathematically given as

2HBr(g) ⇄ H2(g) + Br2(g)

Therefore

Kc = [H2] [Br2] / [HBr]^2

7.04X10^-2 = [H2][Br] / [HBr]^2

Upon final reaction

Kc' = [HBr] / [H2]^1/2*[Br2]^1/2

Hence

[tex]\sqrt{(1/7.04X10^-2)}= [HBr] / [H2]^1/2*[Br]^1/2}\\\\Kc' = \sqrt{(1/7.04X10^-2)[/tex]

Kc' = 3.769  

For more information on Chemical Reaction

https://brainly.com/question/11231920

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