.Heliox is a helium-oxygen mixture that may be used in scuba tanks for divers wo

Question

.Heliox is a helium-oxygen mixture that may be used in scuba tanks for divers working at great depths. It is also used medically as a breathing treatment. A 5.25-L tank holds helium gas at a pressure of 1007 psi. A second 5.25-L tank holds oxygen at a pressure of 267.8 psi. The two gases are mixed in a 5.25-L tank. If the temperature remains the same throughout the process, what is the pressure of the gas mixture in the tank? Assume ideal gas behavior.

.How many grams of chlorine gas are needed to make 6.60 × 106 g of a solution that is 1.60 ppm chlorine by mass?

.Chlorine can be prepared in the laboratory by the reaction of manganese dioxide with hydrochloric acid, HCl(aq), as described by the chemical equation. How much MnO2(s) should be added to excess HCl(aq) to obtain 315 mL of Cl2(g) at 25 °C and 775 Torr?

.Hydrazine, N2H4, may react with oxygen to form nitrogen gas and water. If 2.15 g of N2H4 reacts and produces 0.550 L of N2, at 295 K and 1.00 atm, what is the percent yield of the reaction?

.How long does it take (in minutes) for light to reach Jupiter from the Sun, a distance of 8.538 × 108 km?

The wavelength of some yellow light is 580.0 nm. What is the frequency of this yellow light?

The frequency of the middle B note on a piano is 493.88 Hz. What is the wavelength of this note in centimeters? The speed of sound in air is 343.06 m/s.

Microwave ovens emit microwave energy with a wavelength of 13.0 cm. What is the energy of exactly one photon of this microwave radiation?

How many photons are produced in a laser pulse of 0.314 J at 613 nm?

Explanation / Answer

1)

we know that

final moles of gas = moles of gas in tank1 + moles of gas in tank2

now

n = PV/RT

so

PV/RT = P1V1/RT + P2V2 / RT

so

PV = P1V1 + P2V2

P x 10.5 = ( 1007 x 5.25) + ( 267.8 x 5.25)

P = 637.4

so

the pressure of gas in the mixture is 637.4 psi

2)

ppm = mass of chlorine in mg / mass of solution in kg

so

1.6 = mass of chlorine in mg / 6.6 x 106 x 10-3

mass of chlorine in mg = 10560

so

mass of chlorine in g = 10560 / 1000 = 10.56

so

10.56 grams of chlorine gas is required

3)

we know that

PV = nRT

so

( 775/760) x 0.315 = n x 0.0821 x 298

n = 0.01313

so

moles of Cl2 = 0.01313

now

Mn02 + 4HCl ---> MnCl2 + Cl2 + 2H20

we can see that

moles of Mn02 required = moles of Cl2 produced = 0.01313

now

mass = moles x molar mass

so

mass of Mn02 = 0.01313 x 86.937

mass of MnO2= 1.1414

so

1.1414 grams of MnO2 is required

4)

we know that

moles = mass / molar mass

so

moles of N2H4 = 2.15 / 32 = 0.0671875

now

the reaction is

N2H4 + 02 --> N2 + 2H20

we can see that

theoretical moles of N2 produced = moles of N2H4 taken = 0.0671875

now

PV = nRT

1 x 0.55 = n x 0.0821 x 295

n = 0.022708974

now

% yield = actual x 100 / theoretical

% yield = 0.022708974 x 100 / 0.0671875

% yield = 33.8

so

the percent yield is 33.8 %

5)

we know that

time = distance / speed

time = 8.538 x 10^8 x 1000 / 3 x 10^8

time = 2846 s

time = 2846 / 60 min

time = 47.433

so

it takes 47.433 for light to reach jupiter from sun

6) we know that

f = c / lamda

f = 3 x10^8 / 580 x 10-9

f = 5.172 x 10^14 s-1

7)

we know that

f = c / lamda

493.88 = 343.06 / lamda

lamda = 0.6946 m = 69.46 cm

so

the wavelength is 69.46 cm

8)

E = h x c / lamda

E = 6.626 x 10-34 x 3 x 10^8 / 13 x 10-2

E = 1.529 x 10-24 J

so

energy of one photon is 1.529 x 10-24 J

9)

energy of single photon = h x c / lamda

= 6.626 x 10-34 x 3 x 10^8 / 613 x 10-9

= 3.2427 x 10-19

now

no of photons = total energy / energy of a single photon

no of photons = 0.314 / 3.2427 x 10-19

no of photons = 9.683 x 10^17

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