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IRISSAK [1]
3 years ago
15

The aromatic hydrocarbon cymene (C10H14) is found in nearly 100 spices and fragrances including coriander, anise, and thyme. The

complete combustion of 1.608 g of cymene in a bomb calorimeter (Ccalorimeter = 3.640 kJ/°C) produced an increase in temperature of 19.35°C. Calculate the molar enthalpy of combustion of cymene (ΔHcomb) in kilojoules per mole of cymene.
Chemistry
1 answer:
o-na [289]3 years ago
4 0

Answer:

5878 kJ/mol

Explanation:

According to the law of conservation of energy, the sum of the heat released by the combustion and the heat absorbed by the calorimeter is zero.

Qcomb + Qcal = 0

Qcomb = -Qcal    [1]

The heat absorbed by the calorimeter (Qcal) can be calculated using the following expression:

Qcal = Ccal . ΔT = 3.640 kJ/°C × 19.35°C = 70.43 kJ

where,

Ccal is the heat capacity of the calorimeter

ΔT is the difference in temperature

From [1],

Qcomb = - 70.43 kJ

Since this heat is measured at constant pressure, the molar enthalpy of combustion of cymene is:

\Delta Hcomb=\frac{-70.43kJ}{1.608g} .\frac{134.21g}{mol} =5878kJ/mol

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A latex balloon at sea level and room temperature (25°C) has a volume of 2.42 L. When the balloon is released by the child holdi
yarga [219]

Answer:

The answer to your question is: V2 = 1.94 l

Explanation:

Data

V1 = 2.42 l

T1 = 25°C

P1 = 1 atm

V2 = ?

T2 = 25 -11 = 14°C

P2 = 1(0.7) = 0.7 atm

Formula

P1V1/T1 = P2V2/T2

Clear V2 from the equation

V2 = P1V1T2/ P2T1

V2 = (1)((2.42)(14) / (0.7)(25)

V2 = 33.88 / 17.5

V2 = 1.94 l

6 0
3 years ago
A very old tree limb contains an amount of carbon-14 that is approximately 1/8 of the current atmospheric 14C levels.. Calculate
Tomtit [17]

A.       The radioactive decay equation is N = N0e^{-ln(2)*t/T }

where T is the half-life (5730 years), N0 is the number of atoms at time t = 0 and N is the number at time t.

Rewriting this as:

(N/N0) = e^{-ln(2)*t/T }

Since N = (1/8) N0 and substituting known values:

1/8 = e^{-ln(2)*t/5730}

Taking ln of both sides:

ln(1/8)= -ln(2)*t/5730

t = - 5730 * ln(1/8) / ln (2)

t = 17,190 years

The tree was cut down 17,190 years ago.

B.   N0 = 1,500,000 carbon-14 atoms

Since N = (1/8) N0

N = 187,500 carbon atoms left

3 0
3 years ago
In what situation do we use a volumetric flask, conical flask, pipette and graduated cylinder? Explain your answer from accuracy
Ad libitum [116K]
A volumetric flask is used to contain a predetermined volume of substance and only measures that volume, for example 250 ml.
Conical flasks can be used to measure the volume of substances but the accuracy they provide is usually up to 10ml. Conical flasks are used in titrations, reactions where the liquid may boil, and reactions which involve stirring. 
Pippettes are of two types, volumetric and graduated. Pippettes are used where high accuracy is required and volumetric pippettes come in as little as 1 ml. Pippettes are usually used in titrations.
Graduated cylinders come in a wide variety of sizes and their accuracy can be down to as much as 1 ml. They are used to contain liquids.
3 0
3 years ago
Chem quiz please help
GalinKa [24]

The theoretical and percentage yield for the reaction are:

  • The theoretical yield is 21 g
  • The percentage yield is 119%

<h3>Balanced equation </h3>

CH₄ + 2O₂ —> CO₂ + 2H₂O

Molar mass of CH₄ = 16 g/mol

Mass of CH₄ from the balanced equation = 1 × 16 = 16 g

Molar mass of O₂ = 32 g/mol

Mass of O₂ from the balanced equation = 2 × 32 = 64 g

Molar mass of CO₂ = 44 g/mol

Mass of CO₂ from the balanced equation = 1 × 44 = 44 g

SUMMARY

From the balanced equation above,

16 g of CH₄ reacted with 64 g of O₂ to produce 44 g of CO₂

<h3>How to determine the limiting reactant</h3>

From the balanced equation above,

16 g of CH₄ reacted with 64 g of O₂

Therefore,

20 g of CH₄ will react with = (20 × 64 ) / 16 = 80 g of O₂

From the above calculation, a higher mass (i.e 80 g) of O₂ than what was given (i.e 30 g) is needed to react completely with 20 g of CH₄.

Therefore, O₂ is the limiting reactant

<h3>How to determine the theoretical yield of CO₂</h3>

From the balanced equation above,

64 g of O₂ reacted to produce 44 g of CO₂

Therefore,

30g of O₂ will react to produce = (30 × 44) / 64 = 21 g of CO₂

<h3>How to determine the percentage yield </h3>
  • Actual yield of CO₂ = 25 g
  • Theoretical yield of CO₂ = 21 g
  • Percentage yield =?

Percentage yield = (Actual / Theoretical) × 100

Percentage yield = (25 / 21) ×100

Percentage yield = 119%

Learn more about stoichiometry:

brainly.com/question/14735801

#SPJ1

4 0
2 years ago
A runner runs for a distance of 350 yards and then runs for an additional 200 m. What is the total difference covered by the run
Rudiy27
Answer: 520.04 meters.

If you convert 350 yards to meters, you get 320.04.

320.04m + 200m = 520.04m.

Take off the .04 if necessary:)
3 0
2 years ago
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