Hey guys the below questions are from VCAA 2002:
1). 0.010 mol of chloral hydrate, CCl3CH(OH)2, is dissolved in a pure organic solvent. The resulting solution is made up to one litre exactly. In this solvent, the chloral hydrate dissociates to chloral, CCl3CHO, and water. The chemical reaction for the process is
CCl3CH(OH)2(in solution) CCl3CHO(in solution) + H2O(in solution)
When the reaction has reached equilibrium the concentration of water in the solution is measured to be 0.0020 M.
The equilibrium constant for the reaction at this temperature would be
A. 4.0 × 10–4
B. 5.0 × 10–4
C. 0.20
D. 0.25
The answer is B, and according to the examiner's report: "Students selecting A, made the mistake of omitting to note that, when the 0.010 mol of CCl3CH(OH)2 dissociated to give 0.002 mol of each of two products, then there would be only 0.008 mol of CCl3CH(OH)2 left."
I just don't get why it's 0.008 when it disassociates to give each of the 2 products? Wouldn't you subtract two lots of 0.002?
2). 100 mL of an 0.0100 M aqueous solution of calcium hydroxide will absorb carbon dioxide according to the equation
Ca(OH)2(aq) + 2CO2(g) → Ca(HCO3)2(aq)
The maximum volume, in mL, at STP of CO2 that could be absorbed by the solution is
A. 22.4
B. 44.8
C. 224
D. 448
How do i do this?