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lions [1.4K]
3 years ago
11

The forensic technician at a crime scene has just prepared a luminol stock solution by adding 13.0 g of luminol into a total vol

ume of 75.0 mL of H2O. What is the molarity of the stock solution of luminol?
Chemistry
1 answer:
Andrews [41]3 years ago
3 0

Answer:

0.978 M

Explanation:

Given data

  • Mass of luminol (solute): 13.0 g
  • Volume of the solution = volume of water: 75.0 mL = 0.0750 L

We can find the molarity of the stock solution of luminol using the following expression.

M = mass of solute / molar mass of solute × liters of solution

M = 13.0 g / 177.16 g/mol × 0.0750 L

M = 0.978 M

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Consider a sample of 3.5 mol of N2(g) at T1 = 350 K, that undergoes a reversible and adiabatic change in pressure from p1 = 1.50
devlian [24]

Answer:

Part A is just T2 = 58.3 K

Part B ∆U = 10967.6 x C_{V} You can work out C_{V}

Part C

Part D

Part E

Part F

Explanation:

P = n (RT/V)

V = (nR/P) T

P1V1 = P2V2

P1/T1 = P2/T2

V1/T1 = V2/T2

P = Pressure(atm)

n = Moles

T = Temperature(K)

V = Volume(L)

R = 8.314 Joule or 0.08206 L·atm·mol−1·K−1.

bar = 0.986923 atm

N = 14g/mol

N2 Molar Mass 28g

n = 3.5 mol N2

T1 = 350K

P1 = 1.5 bar = 1.4803845 atm

P2 = 0.25 bar = 0.24673075 atm

Heat Capacity at Constant Volume

Q = nCVΔT

Polyatomic gas: CV = 3R

P = n (RT/V)

0.986923 atm x 1.5 = 3.5 mol x ((0.08206 L atm mol -1 K-1 x 350 K) / V))

V = (nR/P) T

V = ((3.5 mol x 0.08206 L atm mol -1 K-1)/(1.5 x 0.986923 atm) )x 350K

V = (0.28721/1.4803845) x 350

V = 0.194 x 350

V = 67.9036 L

So V1 = 67.9036 L

P1V1 = P2V2

1.4803845 atm x 67.9036 L = 0.24673075 x V2

100.52343693 = 0.24673075 x V2

V2 = P1V1/P2

V2 = 100.52343693/0.24673075

V2 = 407.4216 L

P1/T1 = P2/T2

1.4803845 atm / 350 K = 0.24673075 atm / T2

0.00422967 = 0.24673075 /T2

T2 = 0.24673075/0.00422967

T2 = 58.3 K

∆U= nC_{V} ∆T

Polyatomic gas: C_{V} = 3R

∆U= nC_{V} ∆T

∆U= 28g x C_{V} x (350K - 58.3K)

∆U = 28C_{V} x 291.7

∆U = 10967.6 x C_{V}

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The 1995 Nobel Prize in Chemistry was shared by Paul Crutzen, F. Sherwood Rowland, and Mario Molina for their work concerning th
castortr0y [4]

Answer:

-162,5 kJ/mol

Explanation:

Cl(g) + 2O2(g) --> ClO(g) + O3(g)  ΔH = 122.8 kJ/mol (as we used the reaction in the opposite direction, it will turn the enthalpy from exothermic to endothermic)

2O3(g) --> 3O2(g)   ΔH = -285.3 kJ/mol

  Cl(g) + O2(g) --> ClO(g) + O3(g)  ΔH = 122.8 kJ

+ 2O3 (g)          --> 3O2(g)              ΔH = - 285.3 kJ

O3(g) + Cl(g)     --> ClO(g) + 2O2(g)  ΔH = 122.8 + (-285.3) = -162,5 kJ

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Answer:

B 100,000%

Explanation:

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