Question

How do I solve:

1) A gas system has pressure, moles, and temperature of 0.832 atm, 0.303 moles and 8.000°C, respectively. What is the volume in L?  

2) A gas system has pressure, volume and temperature of 1500 torr, 3.84 L and 277°K, respectively. How many moles of gas are present?  

3) A gas system has a volume, moles and temperature of 8.65L, 0.652 moles and 229°K, respectively. What is the pressure in torr?  

4) A technician measures the voltage drop of 25 V across a 100-Ω resistor using a digital voltmeter. Ohm’s law states that V = IR . What is the current flow (I) through the resistor (R )? How much power (P in Watts)  is consumed by the resistor? (Hint: P = I2R)          (Answer: 250 mA, 6.25 W)  

Answer 1

1)

We know that PV = nRT

V = nRT/P

n = 0.303 mole,

T = 8⁰C = 8+273.15 = 281.15K,

P= 0.832 atm,

R = 0.08205 L atm mol^-1 K^-1 ( R = gas constant)

V = ?

Substitute these value in above equation.

V = 0.303 X0.08205 X 281.15/0.832 = 8.40 L

volume ot the gas = 8.40 L

2)

Ideal gas equation

PV = nRT             where, P = atm pressure= 1500 torr = 1.9737 atm,

V = volume in Liter = 3.84 L

n = number of mole = ?

R = 0.08205L atm mol^-1 K^-1 =Proportionality constant = gas constant,

T = Temperature in K = 277 K

We can write ideal gas equation

n = PV/RT

Substitute the value

n = (1.9737 X 3.84)/(0.08205 X 277) = 0.3347 mole

mole of gas = 0.3347 mole

3)

PV = nRT             where, P = atm pressure= ?

V = volume in Liter = 8.65 L

n = number of mole = 0.652 mol

R = 0.08205L atm mol^-1 K^-1 =Proportionality constant = gas constant,

T = Temperature in K = 229 K

We can write ideal gas equation

P = nRT/V

Substitute value in above equation

P = 0.652 X0.08205 X 229 / 8.65 = 1.416 atm

1.416 atm = 1076.16 torr

pressure of gas = 1076.16 torr