Please help me out ASAP!


What is meant by concentration?​

Answers

Answer 1

Answer:

concentration is the abundance of a constituent divided by the total volume of a mixture.


Related Questions

Need help finding major products

Answers

Answer:

Explanation:

RX + AgNO₃ = R⁺ ( carbocation ) + AgX + NO₃⁻

C₂H₅OH ( a nucleophile ) + R⁺ = ROC₂H₅

C₅H₁₁X + AgNO₃ = C₅H₁₁⁺ + AgX + NO₃⁻

In the first case carbocation produced is CH₃CH₂CH₂CH₂CH₂⁺

CH₃CH₂CH₂CH₂CH₂⁺ ⇒  CH₃CH₂CH₂C⁺HCH₃ ( secondary carbocation more stable )

CH₃CH₂CH₂C⁺HCH₃ + C₂H₅OH ⇒ CH₃CH₂CH₂CH(OC₂H₅)CH₃

Hence option D is correct .

b )

In the second case carbocation produced is

CH₃CH₂CH₂CH⁺CH₃

CH₃CH₂CH₂C⁺HCH₃ + C₂H₅OH ⇒ CH₃CH₂CH₂CH(OC₂H₅)CH₃

The product formed is same as in case of first

Option B is correct

cetylene gas is often used in welding torches because of the very high heat produced when it reacts with oxygen gas, producing carbon dioxide gas and water vapor. Calculate the moles of oxygen needed to produce of water.

Answers

Answer:

0.60 mol

Explanation:

There is some info missing. I think this is the original question.

Acetylene gas is often used in welding torches because of the very high heat produced when it reacts with oxygen gas, producing carbon dioxide gas and water vapor. Calculate the moles of oxygen needed to produce 1.5 mol of water.

Step 1: Given data

Moles of water required: 1.5 mol

Step 2: Write the balanced equation

C₂H₂(g) + 2.5 O₂(g) ⇒ 2 CO₂(g) + H₂O(g)

Step 3: Calculate the moles of oxygen needed to produce 1.5 mol of water

The molar ratio of O₂ to H₂O is 2.5:1. The moles of oxygen needed to produce 1.5 mol of water are (1/2.5) × 1.5 mol = 0.60 mol

A chemist adds of a M barium chlorate solution to a reaction flask. Calculate the mass in grams of barium chlorate the chemist has added to the flask. Round your answer to significant digits.

Answers

The given question is incomplete, the complete question is:

A chemist adds 200.0 ml of a 0.52M barium chlorate (Ba(CIO3)2) solution to a reaction flask. Calculate the mass in grams of barium chlorate the chemist has added to the flask. Round your answer to significant digits.

Answer:

The correct answer is 32 grams.

Explanation:

Based on the given solution, the molarity of barium chlorate solution given is 0.52 M, this shows that the solution will comprise 0.52 moles in 1 L or 1000 ml of the solution.  

Therefore, in 200 ml, it will comprise 0.52/1000 × 200 moles of Ba(ClO₃)₂,  

= 0.52/1000 × 200 = 0.104 moles

The molecular mass of Ba(ClO₃)₂ is 304.23 gram per mole

So, the mass of Ba(ClO₃)₂ in 0.104 moles will be,  

= 304.23 g/mol × 0.104

= 31.639 grams or 32 grams.  

A chemistry student weighs out of chloroacetic acid into a volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with solution. Calculate the volume of solution the student will need to add to reach the equivalence point. Round your answer to significant digits.

Answers

Answer:

11.6mL of the 0.1400M NaOH solution

Explanation:

0.154g of chloroacetic acid diluted to 250mL. Titrated wit 0.1400M NaOH solution.

The reaction of chloroacetic acid, ClCH₂COOH (Molar mass: 94.5g/mol) with NaOH is:

ClCH₂COOH + NaOH → ClCH₂COO⁻ + Na⁺ + H₂O

Where 1 mole of the acid reacts per mole of the base.

That means the student will reach equivalence point when moles of chloroacetic acid = moles NaOH.

You will titrate the 0.154g of ClCH₂COOH. In moles (Using molar mass) are:

0.154g ₓ (1mol / 94.5g) = 1.63x10⁻³ moles of ClCH₂COOH

To reach equivalence point, the student must add 1.63x10⁻³ moles of NaOH. These moles comes from:

1.63x10⁻³ moles of NaOH ₓ (1L / 0.1400moles NaOH) = 0.0116L of the 0.1400M NaOH =

11.6mL of the 0.1400M NaOH solution

Calculate the [H+] and pH of a 0.0040 M hydrazoic acid solution. Keep in mind that the Ka of hydrazoic acid is 2.20×10−5. Use the method of successive approximations in your calculations or the quadratic formula.

Answers

Answer:

[tex][H^+]=0.000285[/tex]

[tex]pH=3.55[/tex]

Explanation:

In this, we can with the ionization equation for the hydrazoic acid ([tex]HN_3[/tex]). So:

[tex]HN_3~<->~H^+~+~N_3^-[/tex]

Now, due to the Ka constant value, we have to use the whole equilibrium because this is not a strong acid. So, we have to write the Ka expression:

[tex]Ka=\frac{[H^+][N_3^-]}{[HN_3]}[/tex]

For each mol of [tex]H^+[/tex] produced we will have 1 mol of [tex]N_3^-[/tex]. So, we can use "X" for the unknown values and replace in the Ka equation:

[tex]Ka=\frac{X*X}{[HN_3]}[/tex]

Additionally, we have to keep in mind that [tex]HN_3[/tex] is a reagent, this means that we will be consumed. We dont know how much acid would be consumed but we can express a subtraction from the initial value, so:

[tex]Ka=\frac{X*X}{0.004-X}[/tex]

Finally, we can put the ka value and solve for "X":

[tex]2.2X10^-^5=\frac{X*X}{0.004-X}[/tex]

[tex]2.2X10^-^5=\frac{X^2}{0.004-X}[/tex]

[tex]X= 0.000285[/tex]

So, we have a concentration of 0.000285 for [tex]H^+[/tex]. With this in mind, we can calculate the pH value:

[tex]pH=-Log[H^+]=-Log[0.000285]=3.55[/tex]

I hope it helps!

The [H+] and pH of a 0.0040 M hydrazoic acid solution is 0.000296648 and  3.527759

pH based problem:

What information do we have?

Hydrazoic acid solution = 0.0040 M

Ka of hydrazoic acid = 2.20 × 10⁻⁵

We know that weak acids

[H+] = √( Ka × C)

[H+] = √( 2.2 × 10⁻⁵ × 0.0040)

[H+] = 0.000296648

So,

pH = -log [H+]

pH = -log [0.000296648]

Using log calculator

pH = 3.527759

Find more information about 'pH'.

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How many milliliters of 0.0850 M NaOH are required to titrate 25.0 mL of 0.0720 M hydrobromic acid, HBr, to the equivalence point?

Answers

Answer:

21.2 mL

Explanation:

Step 1: Write the balanced equation.

NaOH + HBr ⇒ NaBr + H₂O

Step 2: Calculate the reacting moles of HBr

25.0 mL of 0.0720 M hydrobromic acid react.

[tex]0.0250 L \times \frac{0.0720mol}{L} = 1.80 \times 10^{-3} mol[/tex]

Step 3: Calculate the reacting moles of NaOH

The molar ratio of NaOH to HBr is 1:1. The reacting moles of NaOH are 1/1 × 1.80 × 10⁻³ mol = 1.80 × 10⁻³ mol.

Step 4: Calculate the required volume of NaOH

[tex]1.80 \times 10^{-3} mol \times\frac{1,000mL}{0.0850mol} = 21.2 mL[/tex]

11. How did the solubility product constant Ksp of KHT in pure water compare to its solubility product constant Ksp of KHT in KCl solution? Are these results what you would expect? Why?

Answers

Answer:

Explanation:

KHT is a salt which ionises in water as follows

KHT ⇄ K⁺ + HT⁻

Solubility product Kw= [ K⁺ ] [ HT⁻ ]

product of concentration of K⁺ and HT⁻ in water

In KCl solution , the solubility product of KHT will be decreased .

In KCl solution , there is already presence of K⁺  ion in the solution . So

in the equation  

[ K⁺ ] [ HT⁻ ]  = constant

when K⁺ increases [ HT⁻ ] decreases . Hence less of KHT dissociates due to which its  solubility decreases . It is called common ion effect . It is so because here the presence of common ion that is K⁺ in both salt to be dissolved and in solvent , results in decrease of solubility of the salt .

Identify a process that is NOT reversible. A. melting of steel B. freezing water C. melting of ice D. frying an egg E. deposition of carbon dioxide (gas to solid)

Answers

I’m pretty sure it would be D. Frying an egg

A process that is not a reversible reaction is frying an egg.

What are reversible reactions?

Reversible reactions are those reactions in which product will again change into the reactant.

Melting of steel and ice are reversible reaction as after cooling again we get the original state of steel and ice.Freezing of water is also reversible reaction as at normal temperature we get the original state of water.Deposition of carbon dioxide is also a reversible reaction.Frying an egg is a non reversible reaction as after frying an egg we didn't get the original egg again.

Hence option (D) is correct.

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what is the difference between acidic and basic protein​

Answers

Answer:

Acidic proteins are proteins that move faster than serum albumin on zone electrophoresis (starch or acrylamide gel) and which bind most strongly to the basic ion exchangers used in protein chromatography.

Basic protein is a late gene product associated with the viral DNA within the nucleocapsid. The harnessing of this promoter allows the expression of foreign genes at earlier times than those using the very late phase promoters of the polyhedron and p10 genes.

Answer:

Acidic proteins are proteins that move faster than serum albumin on zone electrophoresis (starch or acrylamide gel) and which bind most strongly to the basic ion exchangers used in protein chromatography.

Basic protein is a late gene product associated with the viral DNA within the nucleocapsid. The harnessing of this promoter allows the expression of foreign genes at earlier times than those using the very late phase promoters of the polyhedron and p10

Explanation:

Calculate the maximum wavelength of light that will cause the photoelectric
effect for potassium. Potassium has work function 2.29 eV = 3.67 x 10-19 J.

Answers

Answer:

Explanation:

Work function of potassium = 2.29 eV = 3.67 X 10⁻¹⁹ J

So the minimum energy of photon must be equal to 3.67 X 10⁻¹⁹ J .

energy of photon of wavelength λ = hc / λ

where h = 6.67  x 10⁻³⁴

c = 3 x 10⁸

Putting the values in the equation above

6.67  x 10⁻³⁴  x  3 x 10⁸ / λ =  3.67 X 10⁻¹⁹

λ  = 6.67  x 10⁻³⁴  x  3 x 10⁸ /  3.67 X 10⁻¹⁹

= 5.452 x 10⁻⁷

= 5452 x 10⁻¹⁰ m

= 5452 A .

Charcoal from the dwelling level of the Lascaux Cave in France gives an average count of 0.97 disintegrations of ^14 C per minute per gram of sample. Living wood gives 6.68 disintegrations per minute per gram. Estimate the date of occupation and hence the probable date of the wall painting in the Lascaux Cave. Hint: Disintegrations per minute per gram" has the same units as the time-derivative of concentration for a radioactive decay model. (You may use the fact that the half-life of ^14C is 5568 years.)

Answers

Answer:

Explanation:

count given by old sample = .97 disintegrations per minute per gram

count given by fresh sample = 6.68 disintegrations per minute per gram

Half life of radioactive carbon = 5568 years

rate of disintegration

dN / dt = λ N

In other words rate of disintegration is proportional to no of radioactive atoms present . As number reduces rate also reduces .

Let initial no of radioactive be N₀ and after time t , number reduces to N

N₀ / N = 6.68 / .97

Now

[tex]N=N_0e^{-\lambda t}[/tex]

[tex]\frac{N}{N_0} =e^{-\lambda t}[/tex]

[tex]\frac{6.68}{.97} = e^{\lambda t}[/tex]

λ is disintegration constant

λ = .693 / half life

= .693 / 5568

= .00012446 year⁻¹

Putting the values in the equation above

[tex]\frac{6.68}{.97} = e^{.00012446\times t}[/tex]

[tex]6.8866 = e^{.00012446\times t}[/tex]

1.929577 = .00012446 t

t = 15503.6 years .  

30. What is the Bronsted base of H2PO4- + OH- ⟶HPO42- + H2O?

Answers

Answer:

OH⁻ is the Bronsted-Lowry base.

Explanation:

A Bronsted-Lowry base is a substance that accepts protons. In the chemical equation, OH⁻ accepts a proton from H₂PO₄⁻ to become H₂O. H₂PO₄⁻ would be a Bronsted-Lowry acid because it donates a proton to OH⁻ and becomes HPO₄²⁻.

Hope that helps.

Identify a homogeneous catalyst:

a. SO2 over vanadium (V) oxide
b. H2SO4 with concentrated HCl
c. Pd in H2 gas
d. N2 and H2 catalyzed by Fe
e. Pt with methane

Answers

Answer:

b, H2SO4 with HCl, as they are both liquid acids

Which, if any, of the two molecular geometries is likely to be polar if the outer atoms are identical and there is a difference in electronegativity between the central atom and the outer atoms

Answers

Answer:

Polar molecules are not symmetrical

Explanation:

Even though the structures of the molecules involved were not shown in the question, but I will proceed to give a general explanation of the conditions that describe a polar molecule.

First of all, symmetrical molecules are non-polar and asymmetrical molecules are polar. This is the reason why CF4 will be a nonpolar molecule but H2O will be a polar molecule. Some symmetrical molecules may may posses polar bonds or dipoles but these dipoles eventually cancel out since the molecule is symmetrical in nature.

Summarily, if a molecule possess the same type of atoms attached to the central atom with some symmetry axes, like C3, C4 etc., we will end up with a non polar molecule but if we have a nonplanar molecule, then we will end up finding it to be polar.

below are three reactions showing how chlorine from CFCs (chlorofluorocarbons) destroy ozone (O3) in the stratosphere. Ozone blocks harmful ultraviolet radiation from reaching earth’s surface. Show how these 3 equations sum to produce the net equation for the decomposition of two moles of ozone to make three moles of diatomic oxygen (2 O3→ 3 O2), and calculate the enthalpy change. (6 points) R1 O2 (g) → 2 O (g) ΔH1°= 449.2 kJ R2 O3 (g) + Cl (g) → O2 (g) + ClO (g) ΔH2° = -126 kJ R3 ClO (g) + O (g) → O2 (g) + Cl (g) ΔH3°= -268 kJ

Answers

Answer:

ΔH = -338.8kJ

Explanation:

it is possible to sum the enthalpy changes of some reactions to obtain the enthalpy change of the whole reaction (Hess's law).

Using the reactions:

R₁ O₂(g) → 2O(g) ΔH₁°= 449.2 kJ

R₂ O₃(g) + Cl(g) → O₂(g) + ClO(g) ΔH₂° = -126 kJ

R₃ ClO (g) + O (g) → O₂ (g) + Cl (g) ΔH₃°= -268 kJ

By the sum 2R₂ + 2R₃:

(2R₂ + 2R₃) = 2O(g) + 2O₃(g) → 4O₂(g)

ΔH = 2ₓ(-126kJ) + (2ₓ-268kJ) = -788kJ

Now, this reaction + R₁

2O₃(g) → 3O₂(g)

ΔH = -768kJ + 449.2kJ

ΔH = -338.8kJ

You are given a sample of metal and asked to determine its specific heat. You weigh the sample and find that its weight is 30.0 N. You carefully add 1.25×10^4 J of heat energy to the sample and find that its temperature rises 15.0 °C. What is the sample's specific heat?

Answers

Answer:

272.33 J/Kg°C

Explanation:

Data obtained from the question include the following:

Weight of metal = 30 N

Heat used (Q) = 1.25×10⁴ J

Change in temperature (ΔT) = 15.0 °C.

Specific heat capacity (C) =..?

Next, we shall determine the mass of the metal.

The mass of the metal can be obtained as follow:

Weight (W) = mass (m) x acceleration due to gravity (g)

W = mg

Weight of metal = 30 N

Acceleration due to gravity = 9.8 m/s²

Mass (m) =..?

W = mg

30 = m x 9.8

Divide both side by 9.8

m = 30/9.8

m = 3.06 Kg

Finally, we shall determine the specific heat capacity of the metal as show below:

Heat used (Q) = 1.25×10⁴ J

Change in temperature (ΔT) = 15.0 °C.

Mass (m) = 3.06 Kg

Specific heat capacity (C) =..?

Q = mCΔT

1.25×10⁴ = 3.06 x C x 15

Divide both side by 3.06 x 15

C = (1.25×10⁴) / (3.06 x 15)

C = 272.33 J/Kg°C

Therefore, the specific heat capacity of metal is 272.33 J/Kg°C.

After the reaction between sodium borohydride and the ketone is complete, the reaction mixture is treated with water and H2SO4 to produce the desired alcohol. Explain the reaction by clearly indicating the source of the hydrogen atom that ends up on the oxygen

Answers

Answer:

The hydrogen can be gotten from the added Acid or water during "workup".

Explanation:

Basically we can say that the reaction describe in this question is a Reduction reaction because of the chemical compound called sodium borohydride. In the reaction described above we can see that there is a Reduction of ketone to alcohol by the compound; sodium borohydride.

For the reduction Reaction to occur the C-O bond must break so as to enable the formation of O-H bond and C-H bond.

So, "the reaction mixture is treated with water and H2SO4 to produce the desired alcohol", thus, the oxygen will definitely pick up the hydrogen from H2SO4 or H2O.

A sample of neon gas at a pressure of 0.609 atm and a temperature of 25.0 °C, occupies a volume of 19.9 liters. If the gas is compressed at constant temperature to a
volume of 12.7 liters, the pressure of the gas sample will be
atm.​

Answers

Answer:

The pressure of the gas sample will be  0.954 atm.​

Explanation:

Boyle's law states that the pressure of a gas in a closed container is inversely proportional to the volume of the container, when the temperature is constant. That is, if the pressure increases, the volume decreases; conversely if the pressure decreases, the volume increases.

Boyle's law is expressed mathematically as:

Pressure * Volume = constant

o P * V = k

To determine the change in pressure or volume during a transformation at constant temperature, the following is true:

P1 · V1 = P2 · V2

That is, the product between the initial pressure and the initial volume is equal to the product of the final pressure times the final volume.

In this case:

P1= 0.609 atmV1= 19.9 LP2=?V2= 12.7 L

Replacing:

0.609 atm* 19.9 L= P2* 12.7 L

Solving:

[tex]P2=\frac{0.609 atm* 19.9 L}{12.7 L}[/tex]

P2= 0.954 atm

The pressure of the gas sample will be  0.954 atm.​

The ionization constant of lactic acid ch3ch(oh) co2h am acid found in the blood after strenuous exercise is 1.36×10^-4 If 20.0g of latic acid is used to make a solution with a volume of 1.00l what is the concentration of hydronium ion in the solution

Answers

Answer:

Explanation:

CH₃CHOHCOOH    ⇄    CH₃CHOHCOO⁻   +    H⁺

ionisation constant = 1.36 x 10⁻⁴ .

molecular weight of lactic acid = 90 g

moles of acid used = 20 / 90

= .2222

it is dissolved in one litre so molar concentration of lactic acid formed

C = .2222M

Let n be the fraction of moles ionised  

CH₃CHOHCOOH    ⇄    CH₃CHOHCOO⁻   +    H⁺

C  - nC                                          nC                  nC

By definition of ionisation constant Ka

Ka = nC x nC / C - nC

= n²C ( neglecting n in the denominator )

n² x .2222 = 1.36 x 10⁻⁴

n = 2.47  x 10⁻²

nC = 2.47  x 10⁻² x .2222

= 5.5 x 10⁻³

So concentration of hydrogen or hydronium ion = 5.5  x 10⁻³ g ion per litre .

The concentration of hydrogen or hydronium ion = 5.5  x 10⁻³ g ion per liter .

Ionization of lactic acid can be represented as:

CH₃CHOHCOOH⇄ CH₃CHOHCOO⁻  + H⁺

Given:

ionization constant = 1.36 x 10⁻⁴

mass= 20.0 g

Now, Molecular weight of lactic acid = 90 g

[tex]\text{Number of moles}=\frac{20}{90} =0.22mol[/tex]

It is dissolved in 1.00L so molar concentration of lactic acid formed will be

C = 0.22M

Consider "n" to be the fraction of moles ionized  

CH₃CHOHCOOH    ⇄    CH₃CHOHCOO⁻   +    H⁺

C  - nC                                          nC                  nC

By definition of ionization constant Ka

[tex]K_a =\frac{nC*nC}{C-nC}[/tex]

[tex]K_a= n^2C[/tex] ( neglecting n in the denominator )

On substituting the values we will get:

[tex]n^2 *0.22 = 1.36 *10^{-4}\\\\n = 2.47 * 10^{-2}[/tex]

To find the concentration of hydronium ion in the solution,

[tex]nC = 2.47 *10^{-2} *0.22\\\\nC= 5.5 * 10^{-3}[/tex]

So, concentration of hydrogen or hydronium ion = 5.5  x 10⁻³ g ion per liter.  

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What mass of Si, in grams, can be produced from the reaction below starting with 225 g SiCl4 and 101 g Mg? SiCl4 + Mg  Si + MgCl2 Given: 1 mol SiCl4 = 169.8963 g SiCl4 1 mol Mg = 24.3050 g Mg 1 mol Si = 28.0855 g Si

Answers

Answer:

[tex]m_{Si}=37.2gSi[/tex]

Explanation:

Hello,

In this case, for the undergoing balanced chemical reaction:

[tex]SiCl_4 + 2Mg \rightarrow Si + 2MgCl_2[/tex]

We must first identify the limiting reactant given the 225 g of SiCl4 and 101 g of Mg. Thus, we compute the available moles of SiCl4:

[tex]n_{SiCl_4}=225gSiCl_4*\frac{1molSiCl_4}{169.8963gSiCl_4}=1.324molSiCl_4[/tex]

Next, by using the 1:2 mole ratio between SiCl4 and Mg, we compute the moles of SiCl4 consumed by 101 g of Mg:

[tex]n_{SiCl_4}^{consumed}=101gMg*\frac{1molMg}{24.3050gMg} *\frac{1molSiCl_4}{2molMg} =2.08molSiCl_4[/tex]

Thus, since less moles of SiCl4 are available, we can infer it is the limiting reactant whereas the Mg is in excess. In such a way, the produced grams of Si are computed considering the 1:1 molar ratio between SiCl4 and Si:

[tex]m_{Si}=1.324molSiCl_4*\frac{1molSi}{1molSiCl_4} *\frac{28.0855gSi}{1molSi} \\\\m_{Si}=37.2gSi[/tex]

Best regards.

Calculate the volume in liters of a M mercury(II) iodide solution that contains of mercury(II) iodide . Round your answer to significant digits.

Answers

Answer:

41L

Explanation:

Of a 4.8x10⁻⁵M mercury (II) iodide that contains 900mg of mercury (II) iodide. 2 significant digits

Molarity, M, is an unit of concentration in chemistry defined as the ratio between moles of solute (Mercury (II) iodide in this case) per Liter of solution.

A 4.8x10⁻⁵M solution contains 4.8x10⁻⁵ moles of solute per liter.

Now, 900mg = 0.900g of mercury (II) iodide (Molar mass: 454.4g/mol) are:

0.900g × (1mol / 454.4g) = 1.98x10⁻³moles of HgI₂

If in 1L there are 4.8x10⁻⁵ moles of HgI₂, There are 1.98x10⁻³moles of HgI₂ in:

1.98x10⁻³moles of HgI₂ ₓ (1L / 4.8x10⁻⁵moles) =

41L

can I get some urgent help please?​

Answers

Answer:

hi here goes your answer

Explanation:

iv. The lower the PH, the weaker the base

what is the meaning of the word tetraquark?​

Answers

Answer:

A tetraquark in physics is an exotic meson composed of four valence quarks.

Explanation:

It has been suspected to be allowed by quantum chromodynamics, the modern story of strong interactions.

Hope it helps.

Select the correct answer. A certain reaction has this form: aA bB. At a particular temperature and [A]0 = 2.00 x 10-2 Molar, concentration versus time data were collected for this reaction and a plot of ln[A]t versus time resulted in a straight line with a slope value of -2.97 x 10-2 min-1. What is the half-life of this reaction? A. 23.33 seconds B. 0.043 minutes C. 0.0043 seconds D. 23.33 minutes E. 1680 minutes

Answers

Answer:

[tex]\large \boxed{\text{D. 23.34 min}}[/tex]

Explanation:

1. Find the order of reaction

Use information from the graph to find the order.

If a plot of ln[A] vs time is linear, the reaction is first order and the slope = -k.

2. Find the  half-life

[tex]k = \dfrac{\ln2}{ t_{\frac{1}{2}}}\\\\k = \text{-slope} = -(-2.97 \times 10^{-2} \text{ min}^{-1}) =2.97 \times 10^{-2} \text{ min}^{-1} \\ t_{\frac{1}{2}} =\dfrac{\ln 2}{k} = \dfrac{\ln 2}{2.97 \times 10^{-2}\text{ min}^{-1}} =\textbf{23.34 min}\\\\\text{The half-life is $\large \boxed{\textbf{23.34 min}}$}[/tex]

The half life of the reaction is 23.33 minutes.

We know that for a first order reaction;

ln[A]t = ln[A]o  - kt

A plot of ln[A]t  against time (t) will yield a straight line graph with a slope of -k.

From the question, the slope is -2.97 x 10-2 min-1.

So, -2.97 x 10-2 min-1 = - k

k = 2.97 x 10-2 min-1

The half life of a first order reaction is obtained from;

t1/2 = 0.693/k

t1/2 = 0.693/2.97 x 10-2 min-1

t1/2 = 23.33 minutes

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A reaction is performed in a lab whereby two solutions are mixed together. The products are a liquid and a solid precipitate. What procedures would facilitate measurement of actual yield of the solid

Answers

Answer:

filtration, drying, and weighing

Explanation:

The procedures that would facilitate the measurement of the actual yield of the solid would be filtration of the precipitate, drying of the precipitate, and weighing of the precipitate respectively.

The liquid/solid mixture resulting from the reaction can be separated by the process of filtration using a filter paper. The residue in the filter paper would be the solid while the filtrate would be the liquid portion of the reaction's product.

The residue can then be allowed to dry, and then weighed using a laboratory-grade weighing balance. The weight of the solid represents the actual yield of the solid.

What was one idea Dalton taught about atoms?
A. Atoms contained negatively charged particles scattered inside.
B. Atoms of one type would not react with atoms of another type.
C. All atoms of one type were identical in mass and properties.
D. Atoms changed into new elements when they formed compounds.

Answers

Answer:

C

Explanation:

I had this question and C is the right answer

One idea that Dalton taught about atoms was that all atoms of one type were identical in mass and properties.

What is an atom?

An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.

The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.

Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.

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Write the equilibrium constant expression for the experiment you will be studying this week. 2. If the equilibrium values of Fe3+, SCN- and FeSCN2+ are 9.5 x 10-4 M, 3.6 x 10-4 M and 5.7 x 10-5 M respectively, what is the value of Kc? 3. Write the general form of the dilution equation. 4. A solution is prepared by adding 18 mL of 0.200 M Fe(NO3)3 and 2 mL of 0.0020 M KSCN. Calculate the initial concentrations of Fe3+ and SCNin the solution.

Answers

Answer:

Kc = 166.7

[Fe³⁺] =  0.18 M

[SCN⁻] = 2×10⁻⁴ M

Explanation:

In the reaction of Fe³⁺ and SCN⁻, it is formed a complex:

Fe³⁺  +  SCN⁻  ⇄  FeSCN²⁺             Kc

Let's make the expression for Kc →  [FeSCN²⁺] / [Fe³⁺] . [SCN⁻]

5.7×10⁻⁵ / 9.5×10⁻⁴. 3.6×10⁻⁴  = 166.7

We determine the mmoles, we add from each reactant:

18 ml . 0.2M = 3.6 mmoles of Fe³⁺

2 ml . 0.002M = 4×10⁻³ mmoles of SCN⁻

General form of the dilution equation is:

Concentrated [C] . Concentrated Volume = Diluted [C] . Diluted Volume

Total volume = 20mL

[Fe³⁺]: 3.6 mmoles /20mL = 0.18 M

[SCN⁻]: 4×10⁻³ mmoles /20mL = 2×10⁻⁴ M

The value should be 1.67 x 10^2

The initial concentration should be 0.18 M and 2.0 x 10^(-4) M

Calculation of the value and initial concentration:

The value is

= 5.7 x 10^(-5)/(9.5 x 10^(-4) x 3.6 x 10^(-4))

= 167

= 1.67 x 10^2

we know that

Initial moles  = volume x concentration

So,

= 18/1000 x 0.200

= 0.0036 mol

Now

Initial moles  = volume x concentration

= 2/1000 x 0.0020

= 4.0 x 10^(-6) mol

So,

Total volume should be

= 18 + 2

= 20 mL

= 0.02 L

Now

Initial concentration   

= moles /total volume

= 0.0036/0.02

= 0.18 M

Now

Initial concentration

= moles  /total volume

= 4.0 x 10^(-6)/0.02

= 2.0 x 10^(-4) M

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A student mixes wants to prepare 24.1 mmol of benzamide from benzoyl chloride and NH4OH. If the student uses excess 15 M NH4OH, how many mL of Benzoyl chloride must be used

Answers

Answer:

2.81mL

Explanation:

Based on the reaction:

C₆H₃COCl + 2NH₃ → C₆H₅CONH₂ + NH₄Cl

Benzoyl chloride + ammonia → Benzamide

1 mole of benzoyl chloride in excess of ammonia produce 1 mole of Benzamide.

Thus, assuming a theoretical yield, to produce 24.1mmoles of benzamide you require 24.1mmoles of benzoyl chloride.

As molar mass of benzoyl chloride is 141g/mol, mg you require are:

mg Benzoyl chloride: 24.1mmol × (141mg / 1mmol) = 3398.1mg = 3.3981g of benzoyl chloride.

to convert this mass to mL, you require density of Benzoyl chloride (1.21g/mL). Thus, mL you need are:

3.3981g × (1mL / 1.21g) =

2.81mL

When the following molecular equation is balanced using the smallest possible integer coefficients, the values of these coefficients are:
P2O5 (s) + H2O (l) =H3PO4 (aq)
The balanced chemical equation for the reaction between hydrogen sulfide and oxygen is:
2H2S(g) + 3O2(g) =2H2O(l) + 2SO2(g)
We can interpret this to mean:
3moles of oxygen and_______moles of hydrogen sulfide react to produce______moles of water and_______ moles of sulfur dioxide.

Answers

Answer:

1. The coefficients are: 1, 3, 2

2. From the balanced equation, we obtained the following:

3 moles oxygen, O2 reacted.

2 moles of Hydrogen sulfide, H2S reacted.

2 moles of water were produced.

2 moles of sulphur dioxide, SO2 were produced.

Explanation:

1. Determination of the coefficients of the equation.

This is illustrated below:

P2O5(s) + H2O(l) <==> H3PO4(aq)

There are 2 atoms of P on the left side and 1 atom on the right side. It can be balance by putting 2 in front of H3PO4 as shown below:

P2O5(s) + H2O(l) <==> 2H3PO4(aq)

There are 2 atoms of H on the left side and 6 atoms on the right side. It can be balance by putting 3 in front of H2O as shown below:

P2O5(s) + 3H2O(l) <==> 2H3PO4(aq)

Now the equation is balanced.

The coefficients are: 1, 3, 2.

2. We'll begin by writing the balanced equation for the reaction. This is given below:

2H2S(g) + 3O2(g) => 2H2O(l) + 2SO2(g)

From the balanced equation above,

3 moles of oxygen, O2 reacted with 2 moles of Hydrogen sulfide, H2S to produce 2 moles of water, H2O and 2 moles of sulphur dioxide, SO2.

How to do this
Q1 and Q2
Only want to know how to find molecular formula

Answers

Answer:

Question 1

A. Empirical formula is C8H8O3

B. Molecular formula is C8H8O3

Question 2.

A. Empirical formula is CH2

B. Molecular formula is C4H8

Explanation:

Question 1:

A. Determination of the empirical formula:

Carbon (C) = 63.2%

Hydrogen (H) = 5.26%

Oxygen (O) = 31.6%

Divide by their molar mass

C = 63.2/12 = 5.27

H = 5.26/1 = 5.26

O = 31.6/16 = 1.975

Divide by the smallest

C = 5.27/1.975 = 2.7

H = 5.26/1.975 = 2.7

O = 1.975/1.975 = 1

Multiply through by 3 to express in whole number

C = 2.7 x 3 = 8

H = 2.7 x 3 = 8

O = 1 x 3 = 3

Therefore, the empirical formula for the compound is C8H8O3

B. Determination of the molecular formula of the compound.

From Avogadro's hypothesis, 1 mole of any substance contains 6.02×10²³ molecules.

Now from the question given, we were told that 1 molecule of the compound has a mass of 2.53×10¯²² g.

Therefore, 6.02×10²³ molecules will have a mass of = 6.02×10²³ x 2.53×10¯²² = 152.306 g

Therefore, 1 mole of the compound = 152.306 g

The molecular formula of the compound can be obtained as follow:

[C8H8O3]n = 152.306

[(12x8) + (1x8) + (16x3)]n = 152.306

[(96 + 8 + 48 ]n = 152.306

152n = 152.306

Divide both side by 152

n = 152.306/152

n = 1

The molecular formula => [C8H8O3]n

=> [C8H8O3]1

=> C8H8O3

Question 2:

A. Determination of the empirical formula of the compound.

Mass sample of compound = 0.648 g

Carbon (C) = 0.556 g

Mass of Hydrogen (H) = mass sample of compound – mass of carbon

Mass of Hydrogen (H) = 0.648 – 0.556

Mass of Hydrogen (H) = 0.092 g

Thus, the empirical formula can be obtained as follow:

C = 0.556 g

H = 0.092 g

Divide by their molar mass

C = 0.556/12 = 0.046

H = 0.092/1 = 0.092

Divide by the smallest

C = 0.046/0.046 = 1

H = 0.092/0.046 = 2

Therefore, the empirical formula of the compound is CH2.

B. Determination of the molecular formula of the compound.

Mole of compound = 0.5 mole

Mass of compound = 28.5 g

Molar mass of compound =.?

Mole = mass /Molar mass

0.5 = 28.5/ Molar mass

Cross multiply

0.5 x molar mass = 28.5

Divide both side by 0.5

Molar mass = 28.5/0.5 = 57 g/mol

Thus, the molecular formula of compound can be obtained as follow:

[CH2]n = 57

[12 + (1x2)]n = 57

14n = 57

Divide both side by 14

n = 57/14

n = 4

Molecular formula => [CH2]n

=> [CH2]4

=> C4H8.

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