ssNake's Chemistry [u2] Q's

[Lasercookie]

Also remember that the molar volume is "the volume occupied by one mole of a substance at a given temperature and pressure."

Note that in that worked example 21.5c (that's the one you're talking about right?), that they have set n2 to be 1 mole.

[REBORN]

err yeah THEY set it....how the hell am I meant to know that by just reading the question itself? :S

[Lasercookie]

err yeah THEY set it....how the hell am I meant to know that by just reading the question itself? :S

Molar volume.... n must be 1.

If it wasn't 1, then it wouldn't be molar volume.

[REBORN]

FACEPALM.

[Graphite]

Yea use the ideal gas equation stead. That equation is derived from the ideal gas equation and is never needed simply because the constant is universally known

[REBORN]

Mg_xN_y + ZH₂O ----> xMg(OH)₂ + yNH₃

a) After the reaction is complete 4.437g of Magnesium Hydroxide is produced: determine the mass of magnesium in the original Mg_xN_y compound.

b) If at the end of the reaction 0.8626g of ammonia was liberated determine the mass of nitrogen in the original Mg_xN_y compound.

--------

Explanations alongside workings would be MUCH appreciated

[REBORN]

Someone solve please?

[luken93]

Finding n(Mg(OH)2) will also give you n(Mg) and n(OH).
 - Since all of the O in H2O goes to MgOH2, you can determine Z.
 - Since Mg is 2+, and N is 3-,you know it will be in the ratio of 3:2. This will give you Y as well...

[REBORN]

With reference to scuba diving and Boyle's law:

1) What happens to the pressure inside a diver's lungs if he or she returns to the surface without breathing?

[Russ]

Pressure will decrease, so the volume of the gas will increase (with all the consequences that come with that)

[REBORN]

Their answer: The pressure inside the lungs is high. Under these conditions, expansion of the lungs can cause injury

Why 'high'? I thought pressure would decrease....

[Russ]

I'm no chemist but they're referring to the pressure of the gas/air inhaled when he was diving. It was inhaled at a high pressure, so as he rises it begins to expand.

I can't remember physics enough to say whether or not pressure actually decreases though, maybe someone who knows what they're talking about can help you.

[Mao]

The pressure inside the lungs won't actually change, considering the lungs won't be able to expand that much.

The amount of gas inside the lungs won't change. Therefore, if we assume the lung keeps its volume when the diver reaches the surface, that is, volume remains constant, then the pressure does not change.

Once the diver reaches the surface, the pressure outside of the lungs will be significantly less than the pressure inside the lungs, thus the pressure differences between air inside and outside the lungs cause a huge strain on the organ, which may lead to ruptures/etc.

[REBORN]

50ml of 3M H3PO4 is diluted to 800mL. What volume of this diluted solution contains 1.5 x 10^-2 mol of H3PO4?

Is the answer 0.08L

[Greatness]

50ml of 3M H3PO4 is diluted to 800mL. What volume of this diluted solution contains 1.5 x 10^-2 mol of H3PO4?

Is the answer 0.08L

Yep that's what i got