[al526]

A 0.250 L bottle contains 75.0 mL of a 3.0% by mass solution of hydrogen peroxide (H2O2). How much will the pressure (in mm Hg) in the bottle incrase of the H2O2 decomposes to H2O (l) and O2 (g) at 34 degrees Celsius?
(Denisty of solution is 1.00g/mL and volume of liquid doesn't changue during dcomposition)

Answer: 2860 mm Hg


    I don't quite understand the information this question is giving me. So are they basically asking for the pressure the O2 gas is exerting? how i do calculate the difference in pressure?

I realize that 75 mL of the solution contains 0.066 M of H2O2.
and Also, the decomposition equation is
H2O2= 2H2O+O2.

If anyone could help me or clarify the question, that'd be great.

thanks.

[Borek]

So are they basically asking for the pressure the O2 gas is exerting?

Yes.

how i do calculate the difference in pressure?

Initially there was 250-75 mL of "something" above the solution. This "something" had some pressure. Increase in the pressure can be attributed to the partial pressure of evolved oxygen. So it is enough to calculate pressure of oxygen - that's already the difference.