Question

4.(20pts) Valves closed He (ideal gas) (Flask on left) V 2.50 L P 425 torr Ne (ideal gas) (Flask in middle) V 7.00 L P 677 torr Flesk on Right V 3.00 L P 0 (vacuum) When the valves are open, the gases will mix. Assuming that the temperature is constant, what is the final total pressure in torr? Hint: First compute the partial pressures of each gas after it expands to fill the entire space after the valves are open The Ca in a sample of limestone weighing 0.182g was precipitated by using oxalate ions C2O to produce Ca CO.(s) via the reaction Ca (aq) + C,O (aq)- resulting Ca C2O48) weighed 0.133 g, what was the % Ca in the original sample? 5.(25pts) >Ca C0ds) . If the Bonus Problem (+6pts. No partial credit. A 500.0 mg table of an antacid containing Mg(OH). Al(OH)s, and a binder was dissolved in 50.0 mL of 0.500 M HCI. The resulting solution was acidic, and it needed 30.9 mL of 0.255 M NaOH for neutralization. (a) Calculation the number of moles of OH ions in the tablet. (b) If the tablet contains 5.0 % binder, how many milligrams of Mg(OH): and how many of Al(OH)s does the tablet contain?

Answer 1

4) In the left flask:

Pressure, P1= 425 torr

Volume, V1= 2.50 L

In the middle flask:

Pressure, P2= 677 torr

Volume, V2= 7.00 L

In the right flask:

Pressure, P3= 0 torr

Volume, V3= 3.00 L

So, from Boyle's Law we can say the total pressure-volume in the flasks before and after the valves are opened are constant in a fixed temperature.

So we can write, P1V1+P2V2+P3V3 = PV

Where P= total pressure after the valves are opened = x (let)

and V= total volume after the valves are opened = (2.5+7.0+3.0)L = 12.5L

or, (425torrX2.50L)+(677torrX7.0L)+(0torrX3.0L) = x torrX12.5L

or, x X12.5 L= (1062.5+4739+0) torr-L

or, x = 5801.5 torr-L/12.5 L

or, x = 464.12 torr

So the final pressure will be 464.12 torr.