Confused about a couple of questions about ideal gas laws

Question

Hi everyone, I was doing my assignment and I had a couple of questions I was really stuck on. Here they are.

1.) A volume of an unknown gas is 300 L at STP. What volume will the gas occupy at 0.0 degrees celsius and 1000 torr?

2.) What do ideal gases NOT have? What factors make it possible for real gases to behave like ideal gases?

3.) What pressure is exerted by 0.00306 mol of a gas in a 25.9 mL container at 282K?

4.) A hydrocarbon gas with an empirical formula CH(sub)2 has a density of 1.88 grams per liter at 0 degrees celsius and 1.00 atmosphere. A possible formula for the hydrocarbon is: (Hint: use the density ideal gas equation)

A: CH(sub)2 B: C(sub)2H(sub)4 C: C(sub)3H(sub)6 D: C(sub)4H(sub)8 E: C(sub)5H(sub)10

5.) What volume of hydrogen at STP can be produced when 6.54 g of Zn reacts with hydrochloric acid?

That's about it, I'd appreciate it if I could get these ASAP (preferably with some work so that I can learn it).

I was very confused about when to use what; thanks.

Answer 1

Hi, let me try to get you started.. :)

1) P1V1/ T1 = P2V2/ T2

For STP, Standard Conditions 0.00 °C  =  273 K

1.00 atm  =  760.0 mm Hg  =  101.325 kPa  =  101,325 Pa

So,

(760 torr * 300L) / 273 K = (1000 torr * V2) / 273 K

V2 = 228 L

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2) I think they're looking for the answer: intermolecular forces. If either you have:

1. Extremely high pressures

2. Extremely low temperatures  

then your gas is not ideal. Under normal conditions, the deviation from ideality is nelgible, so we can call them ideal then and only then

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3) Again, assume ideality:

P*(0.0259 L) = (0.00306 mol) (0.082057L atm*·K-1·mol-1) (282K)

P = 2.73 atm

The rest work exactly the same. Remember that density = mass / volume. If you need more help, email me.