# 8.4: Unit 8 Practice Problems

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### Question 1.

If the pressure inside a tank is 100. psi, what is this pressure in kPa, mPa, atm, mmHg?

$\mathrm{100\: \cancel{psi.} \times \dfrac{101\: kPa}{14.7\:\cancel{psi.}}=687\: kPa}$      $\mathrm{100\: \cancel{psi.} \times \dfrac{0.101\: MPa}{14.7\:\cancel{psi.}}=0.687\: MPa}$     $\mathrm{100\: \cancel{psi.} \times \dfrac{1\: atm}{14.7\:\cancel{psi.}}=6.8\: atm}$    $\mathrm{100\: \cancel{psi.} \times \dfrac{760\: mmHg}{14.7\:\cancel{psi.}}=5170\: mmHg}$

### Question 2.

A gas occupies a volume of 17.4L at 11.2 psi, what will it's volume be if the pressure is increased to 13.6psi and the temperature is held constant?

P1V1 = P2V2    (11.2psi)(17.4L) = (13.6psi)(V2 )       V2 = 14.3L

### Question 3.

A gas has a volume of 186mL at 32°C, what will it's volume be if the temperature of the gas is increased to 104°C and the pressure is held constant?

V1/T1 = V2/T2  Remember that when using gas laws, temperature should always be in K.  (186mL) / (305K)  = (V2) / (377K)        V= 230mL

### Question 4.

A container of neon at a pressure of 550mmHg and a temp of 120°C is heated (at a constant volume) until the temperature is 360°C.  What is the new pressure of the heated neon?

P1/T1 = P2/T2  Remember that when using gas laws, temperature should always be in K.  (550mmHg) / (393K)  = (P2) / (633K)        P= 890 mmHg

### Question 5.

A cylinder containing 12.0L of compressed air at 23.0atm and -20.0°C is opened and the air escapes into a room which has a pressure of 0.960atm and warms to 28.0°C, what is the final volume of the air from the cylinder?

### Question 6.

If a gas has a volume of 19.8L at standard temperature and pressure (STP),  how many moles of gas are there?

### Question 7.

If 1.0 grams of a gas occupies a volume of 330mL at STP, what is the molecular weight of the gas?

### Question 9.

A gas occupies 6.4L at 102kPa and 294K, what will the temperature of the gas be at 8.7L and 97kPa?