Question
I would greatly appreciate it if someone could answer number 2&3. I am so confused and need help veryyyyy bad. Please explain how you do it, so that I will know how to in the future. THANK YOU in advance.
You will be using 25.00 mL of 3.00% by mass solution ({mass H2O2/mass solution} *100) of hydrogen peroxide. Assume the density of this solution is 1.000 g/mL. If all of hydrogen peroxide decomposes to water and oxygen according to the reaction What is the total volume of oxygen gas generated if the temperature is 24degree C and the pressure is 770 Torr (760 Torr=1 atm) ? (R=0.08206 L.atn/K.mol) (At this point you can ignore the effect of water vapor). By convention, the rate of the reaction is positive, so that in the reaction of hydrogen peroxide, In this case d means "change in", just like Delta . Suppose you carry out the decomposition reaction using 25.0 mL of a 0.200 M hydrogen peroxide solution and obtain the following results: 8.62 mL of gas is collected in 120 seconds. Assume atmospheric pressure = 760. Torr (1 atm). room temperature = 25.degreeC, and the vapor pressure of water is 24. Torr. How many moles of oxygen arc produced per second? What is the rate of the reaction (d[O2]/dt)? (hint: to find [O2] divide the number of moles of molecular oxygen by the solution volume.) What is the change in the concentration of H2O2 per second (Delta [H2O2]/dt)? What is your hypothesis and what specific procedures do you plan to use to investigate your hypothesis? Do not use the example from the previous page.
Explanation / Answer
1) from the reaction for 1 mole of H2O2 Decomposed we get 1/2mole of O2
thus H2O2 moles decomposed = mass of H2O2/Volume of solution = (3*25/100)/(25/1000) = 30 moles
therefore 30*0.5 = 15 moles of O2 liberated
volume of O2 liberated = n*R*T/P = 15*0.0821*(24+273.15)/(770/760) = 361.18
2)intially it is given that [H2O2]intial = 0.200M
we need to find out [H2O2] final = 2*[O2]final
therefore final moles of O2 formed = PV/RT = 1*8.62/(1000*0.0821*298) = 3.52 * 10^(-4) moles
rate of reaction = d[O2]/dt = (3.52*10^(-4)/0.025)/(120 seconds)
rate of reaction = 1.1758*10^(-4)
now using => -0.5(d[H2O2]/dt) = d[O2]/dt = 1.1758*10^(-4)
d[H202]/dt = -2.35 * 10^(-4)